Virtual Machine MaximumsTable 1 contains configuration maximums related to virtual machines.SCSI controllers per virtual machine 4Devices per SCSI controller 15Devices per virtual machine (Windows) 60Devices per virtual machine (Linux) 60Size of SCSI disk 2TBNumber of virtual CPUs per virtual machine 4Size of RAM per virtual machine 16384MBNumber of NICs per virtual machine 4Number of IDE devices per virtual machine 4Number of floppy devices per virtual machine 2Number of parallel ports per virtual machine 2Number of serial ports per virtual machine 2Size of a virtual machine swap file 16384MBNumber of virtual PCI devices: NICs, SCSI controllers, audio devices(VMware Server only), and video cards (exactly one is present in everyvirtual machine). 6Number of remote consoles to a virtual machine 10 Storage MaximumsTable 2 contains configuration maximums related to ESX Server host storage.MaximumBlock size (MB) 8Raw Device Mapping size (TB) 2Simultaneous power ons of virtual machines on different hosts against asingle VMFS volume (measured in number of hosts). 32Number of hosts per virtual cluster 32Number of volumes configured per server 256Number of extents per volume 32 VMFS-2Volume size 2TB x number ofextents1File size (block size=1 MB) 456GBFile size (block size=8 MB) 2TBFile size (block size=64MB) 27TBFile size (block size=256MB) 64TBNumber of files per volume 256 + (64 x number of extents) VMFS‐3Volume size (block size = 1MB) ~16TB‐4GB2Volume size (block size = 2MB) ~32TB‐8GBVolume size (block size = 4MB) ~64TB‐16GBVolume size (block size = 8MB) 64TBFile size (block size=1MB) 256GBFile size (block size=8MB) 2TBNumber of files per directory unlimitedNumber of directories per volume unlimitedNumber of files per volume unlimited
Fibre ChannelLUNs per server 256SCSI controllers per server 16Devices per SCSI controller 16Number of paths to a LUN 32LUNs concurrently opened by all virtual machines 256LUN ID 255 Storage Maximums (Continued)NFSLUNs per server 256SCSI controllers per server 2LUNs concurrently opened by all virtual machines 256Hardware & software iSCSILUNs per server 256SCSI controllers per server 21 Minimum = 100MB2 ~ denotes an approximate value. Compute Maximumscontains configuration maximums related to ESX Server host compute resources.MaximumNumber of virtual CPUs per server 128Number of cores per server 32Number of (hyper threaded) logical processors per server 32Number of virtual CPUs per core 8 Memory MaximumsContains configuration maximums related to ESX Server host memory.MaximumSize of RAM per server 64GBRAM allocated to service console 800MB Networking MaximumsContains configuration maximums related to ESX Server host networking.Physical NICsNumber of e100 NICs 26Number of e1000 NICs 32Number of Broadcom NICs 20Advanced, physical traitsNumber of port groups 512Number of NICs in a team 32Number of Ethernet ports 32
Virtual NICs/switchesNumber of virtual NICs per virtual switch 1016Number of virtual switches 127 Virtual Center MaximumsContains configuration maximums related to Virtual Center.Number of virtual machines (for management server scalability) 1500Number of hosts per DRS cluster 32Number of hosts per HA cluster 16Number of hosts per Virtual Center server 100 VMware Infrastructure IntroductionVMware Infrastructure is a full infrastructure virtualization suite that provides comprehensive (complete)virtualization, management, resource optimization, application availability, and operational automationcapabilities in an integrated offering. VMware Infrastructure virtualizes and aggregates (collective) theunderlying (original, basic) physical hardware resources across multiple systems and provides pools ofvirtual resources to datacenter in the virtual environment.In addition, VMware Infrastructure brings about a set of distributed services thatEnables fine-grain, policy-driven resource allocation, high availability, and consolidated backup of theentire virtual datacenter. These distributed services enable an IT organization to establish and meet theirproduction Service Level Agreements with their customers in a cost effective manner.VMware Infrastructure includes the following components shown in Figure 1‐1:
VMware ESX Server. A robust, production-proven virtualization layer run on physical servers thatabstracts processor, memory, storage, and networking resources into multiple virtual machines.Virtual Center Management Server (Virtual Center Server). The central point forConfiguring, provisioning, and managing virtualized IT environments.Virtual Infrastructure Client (VI Client). An interface that allows users to connectRemotely to the Virtual Center Server or individual ESX Servers from any Windows PC.Virtual Infrastructure Web Access (VI Web Access). A Web interface that allowsVirtual machine management and access to remote consoles.VMware Virtual Machine File System (VMFS). A high-performance cluster fileSystem for ESX Server virtual machines.VMware Virtual Symmetric Multi-Processing (SMP). Feature that enables a singlevirtual machine to use multiple physical processors simultaneously.VMware VMotion . Feature that enables the live migration of running virtual machines from one physicalserver to another with zero down time, continuous service availability, and complete transaction integrity.VMware HA . Feature that provides easy-to-use, cost-effective high availability for applications running invirtual machines. In the event of server failure, affected virtualMachines are automatically restarted on other production servers that have spare capacity.VMware Distributed Resource Scheduler (DRS) . Feature that allocates and balancescomputing capacity dynamically across collections of hardware resources for virtualmachines.VMware Consolidated Backup (Consolidated Backup) . Feature that provides an Easy-to-use,centralized facility for agent-free backup of virtual machines. It simplifies backup administration andreduces the load on ESX Servers.VMware Infrastructure SDK . Feature that provides a standard interface for VMwareand third-party solutions to access the VMware Infrastructure.ClusterA number of similarly configured x86 servers can be grouped together with connectionsto the same network and storage subsystems to provide an aggregate(total) set of resources in the virtualenvironment, called a cluster.Storage Networks and ArraysFiber Channel SAN arrays, iSCSI SAN arrays, and NAS arrays are widely used storage technologiessupported by VMware Infrastructure to meet different datacenter storage needs. Sharing the storage arraysbetween (by connecting them to) groups of servers via storage area networks allows aggregation of thestorage resources and provides more flexibility in provisioning them to virtual machines.Management ServerThe Virtual Center Management Server provides a convenient single point of control to the datacenter. Itruns on top Windows 2003 Server to provide many necessary datacenter services such as access control,performance monitoring, and configuration. It unifies the resources from the individual computing serversto be shared among virtual machines in the entire datacenter. It accomplishes this by managing the
assignment of virtual machines to the computing servers and the assignment of resources to the virtualmachines within a given computing server based on the policies set by the system administrator.Virtual Datacenter ArchitectureVMware Infrastructure virtualizes the entire IT infrastructure including servers, storage, and networks. Itaggregates these heterogeneous resources and presents a simple and uniform set of elements in the virtualenvironment. With VMware Infrastructure, IT resources can be managed like a shared utility anddynamically provisioned to different business units and projects without worrying about the underlyinghardware differences and limitations.Resources are provisioned to virtual machines based on the policies set by the system administrator whoowns the resources. The policies can reserve a set of resources for a particular virtual machine to guaranteeits performance. The policies can also prioritize and set a variable portion of the total resources to eachvirtual machine. A virtual machine will be prevented from being powered-on (to consume resources) ifdoing so would violate the resource allocation policies.Hosts, Clusters, and Resource PoolsHosts, clusters, and resources pools provide flexible and dynamic ways to organize theaggregated computing and memory resources in the virtual environment and link them back to theunderlying physical resources.A cluster acts and can be managed much like a host. It represents the aggregate computing and memoryresources of a group of physical x86 servers sharing the same network and storage arrays. For example, ifthe group contains eight servers, each server has four dual‐core CPUs running at 4 gigahertz each and 32gigabytes of memory. The cluster will then have 256 gigahertz of computing power and 256 gigabytes ofmemory available for the running virtual machines assigned to it.Resource pools are partitions of computing and memory resources from a single host or a cluster. Anyresource pool can be partitioned into smaller resource pools to further divide and assign resources todifferent groups or for different purposes. In other words, resource pools can be hierarchical and nested.VMware VMotionVMware VMotion, DRS, and HA are distributed services that enable efficient and automated resourcemanagement and high virtual machine availability.Virtual machines run on and consume resources from ESX Server. VMotion enables the migration ofrunning virtual machines from one physical server to another without service interruption, This allowsvirtual machines to move from a heavily loaded server to a lightly loaded one. The effect is a more efficientassignment of resources. With VMotion, resources can be dynamically reallocated to virtual machinesacross physical servers.VMware DRSVMware DRS aids in resource control and management capability in the virtual datacenter. A cluster canbe viewed as an aggregation of the computing and memory resources of the underlying physical hosts puttogether in a single pool. Virtual machines can be assigned to that pool. DRS monitors the workload of therunning virtual machines and the resource utilization of the hosts to assign resources.Using VMotion and an intelligent resource scheduler, VMware DRS automates the task of assigning virtualmachines to servers within the cluster to use the computing and memory resources of that server. DRS does
the calculation and automates the pairing. If a new physical server is made available, DRS automaticallyredistribute the virtual machines using VMotion to balance the workloads. If a physical server must betaken down for any reason, DRS automatically reassigns its virtual machines to other servers.VMware HAVMware HA offers a simple and low cost high availability alternative to application clustering. It enablesquick restart of virtual machines on a different physical server within a cluster automatically if the hostingserver fails. All applications within the virtual machines enjoy the high availability benefit, not just one(through application clustering).HA monitors all physical hosts in a cluster and detects host failures. An agent placed on each physical hostmaintains a heartbeat with the other hosts in the resource pool, and loss of a heartbeat initiates the processof restarting all affected virtual machines on other hosts. HA ensures that sufficient resources are availablein the cluster at all times to restart virtual machines on different physical hosts in the event of host failure.Network ArchitectureA virtual switch works like a layer 2 physical switch. Each server has its own virtual switches. On one sideof the virtual switch are port groups that connect to virtual machines. On the other side are uplinkconnections to physical Ethernet adapters on the server where the virtual switch resides. Virtual machinesconnect to the outside world through the physical Ethernet adapters that are connected to the virtual switchuplinks.A virtual switch can connect its uplinks to more than one physical Ethernet adapter to enable NIC teaming.With NIC teaming, two or more physical adapters can be used to share the traffic load or provide passivefailover in the event of a physical adapter hardware failure or a network outagePort group is a unique concept in the virtual environment. A port group is a mechanism for setting policiesthat govern the network connected to it. A vSwitch can have multiple port groups. Instead of connecting toa particular port on the vSwitch, a virtual machine connects its vNIC to a port group. All virtual machinesthat connect to the same port group belong to the same network inside the virtual environment even if theyare on different physical servers.Port groups can be configured to enforce a number of policies that provide enhancednetworking security, network segmentation, better performance, higher availability,and traffic management:Layer 2 security options . Enforces what vNICs in a virtual machine can do by controlling promiscuousmode, MAC address change, or forged transmits.VLAN support . Allows virtual networks to join a physical VLANs or support QOS policies.Traffic shaping . Defines average bandwidth, peak bandwidth, and burst size.These are policies that can be set to improve traffic management.NIC teaming . Sets the NIC teaming policies for an individual port group or network to share traffic loador provide failover in case of hardware failure.Storage Architecture
The VMware Infrastructure storage architecture consists of layers of abstraction that hide and manage thecomplexity and differences among physical storage subsystems.To the applications and guest operating systems inside each virtual machine, the storage subsystem is asimple virtual Bus Logic or LSI SCSI host bus adapter connected to one or more virtual SCSI.The virtual SCSI disks are provisioned from datastore elements in the datacenter. A datastore is like astorage appliance that serves up storage space for many virtual machines across multiple physical hosts.The datastore provides a simple model to allocate storage space to the individual virtual machines withoutexposing them to the complexity of the variety of physical storage technologies available, such as FibreChannel SAN, iSCSI SAN, direct attached storage, and NAS.A virtual machine is stored as a set of files in a directory in the datastore. A virtual disk inside each virtualmachine is one or more files in the directory. As a result, you can operate on a virtual disk (copy, move,back up, and so on) just like a file. New virtual disks can be .hot‐added. to a virtual machine withoutpowering it down. In that case, a virtual disk file (.vmdk) is created in VMFS to provide new storage for thehot-added virtual disk or an existing virtual disk file is associated with a virtual machine.VMFS is a clustered file system that leverages shared storage to allow multiple physical hosts to read andwrite to the same storage simultaneously. VMFS provides on-disk locking to ensure that the same virtualmachine is not powered on by multiple serversat the same time. If a physical host fails, the on-disk lock for each virtual machine isreleased so that virtual machines can be restarted on other physical hosts.VMFS also features enterprise-class crash consistency and recovery mechanisms, such as distributedjournaling, a crash consistent virtual machine I/O path, and machine state snapshots. These mechanismscan aid quick root-ause and recovery from virtual machine, physical host, and storage subsystem failures.VMFS also supports raw device mapping (RDM). RDM provides a mechanism for a virtual machine tohave direct access to a LUN on the physical storage subsystem (Fibre Channel or iSCSI only). RDM isuseful for supporting two typical types of applications:SAN snapshot or other layered applications that run in the virtual machines. RDM better enables scalablebackup offloading systems using features inherent to the SAN.Any use of Microsoft Clustering Services (MSCS) that spans physical hosts:Virtual-to-virtual clusters as well as physical‐to‐virtual clusters. Cluster data and quorum disks should beconfigured as RDMs rather than as files on a shared VMFS.VMware Consolidated BackupVMware Infrastructure-s storage architecture enables a simple virtual machine backup solution: VMwareConsolidated Backup. Consolidated Backup provides a centralized facility for LAN-free backup of virtualmachines.Consolidated Backup works in conjunction with a third-party backup agent residing on a separate backupproxy server (not on the server running ESX Server) but does not require an agent inside the virtualmachines.The third-party backup agent manages the backup schedule. It starts Consolidated Backup when it is timeto do a back up. When started, Consolidated Backup runs a set of pre-backup scripts to quiesce the virtualdisks to take their snapshots. It then runs a set of post-thaw scripts to restore the virtual machine back tonormal operation. At the same time, it mounts the disk snapshot to the backup proxy server. Finally, thethird-party backup agent backs up the files on the mounted snapshot to its backup targets. By taking
snapshots of the virtual disks and backing them up through a separate backup proxy server, ConsolidatedBackup provides a simple, less intrusive, and low-overhead backup solution for the virtual environment.VirtualCenter Management ServerThe VirtualCenter Management Server components are user access control, core services, distributedservices, and various interfaces.The User Access Control allows the system administrator to create and manage different levels of access tothe VirtualCenter for different users.For example, there might be a user class that manages configuring the physical servers in the datacenterand there might be a different user class that manages only virtual resources within a particular resourcepool.Core Services are basic management services for a virtual datacenter. They include services such as:VM Provisioning . Guides and automates the provisioning of virtual machinesHost and VM Configuration . Allows the configuration of hosts and virtual MachinesResources and Virtual Machine Inventory Management . Organizes virtual machines and resources inthe virtual environment and facilities their managementStatistics and Logging . Logs and reports on the performance and resource utilization statistics ofdatacenter elements, such as virtual machines, hosts, and clustersAlarms and Event Management . Tracks and warns users on potential resource Over-utilization or eventconditions.Task Scheduler . Schedules actions such as VMotion to happen at a given time Distributed Services aresolutions that extend VMware Infrastructure-s capabilities to the next level such as VMware DRS, VMwareHA, and VMware VMotion. Distributed Services allow the configuration and management of thesesolutions centrally from VirtualCenter Management Server.VirtualCenter Server has four key interfaces:ESX Server management . Interfaces with the VirtualCenter agent to manage eachphysical server in the datacenter.VMware Infrastructure API . Interfaces with VMware management clients andThird-party solutions.Database interface . Connects to Oracle or Microsoft SQL Server to store information, such as virtualmachine configurations, host configurations, resources and virtual machine inventory, performancestatistics, events, alarms, user permissions, and roles.Active Directory interface . Connects to Active Directory to obtain user accesscontrol information.
Communication Between Virtual Center and ESX ServerThe Virtual Center communicates with ESX Server.s host agent through the VMwareInfrastructure API (VI API). When a host is first added to Virtual Center, Virtual Centersends a Virtual Center agent to run on the host. That agent communicates with the hostagentThe Virtual Center agent acts as a mini‐Virtual Center Server to perform the followingfunctions:Relays and enforces resource allocation decisions made in Virtual Center, includingthose sent by the DRS enginePasses virtual machine provisioning and configuration change commands to thehost agentPasses host configuration change commands to the host agentCollects performance statistics, alarms, and error conditions from the host agentand sends them to the Virtual Center Management ServerAccessing the Virtual DatacenterUsers can manage the VMware Infrastructure datacenter or access the virtual machineconsole through three different means: the VI Client, Web Access through a Webbrowser, or terminal services (such as Windows Terminal Services or Xterm), Accessing hosts should bedone only by physical host administrators in special circumstances. All relevant functionality that can bedone on the host can also be done in VirtualCenter Server.The VI Client accesses Virtual Center through the VMware API. After the user is authenticated, asession starts in Virtual Center, and the user sees the resources and virtual machines that areassigned to the user. For virtual machine console access, the VI Client first gets the virtualmachine location from Virtual Center through the VMware API. It then connects to the appropriatehost and provides access to the virtual machine console.Users can also access Virtual Center Management Server through the Web browser by first pointing thebrowser to an Apache Tomcat Server set up by Virtual Center Management Server. The Apache TomcatServer mediates the communication between the browser and Virtual Center through the VMware API.To access the virtual machine consoles through the Web browser, users can make use of the bookmark thatis created by VirtualCenter Server. The bookmark first points to the VI Web Access.VI Web Access resolves the physical location of the virtual machine and redirects the Web browser to theESX Server where the virtual machine resides.
If the virtual machine is running and the user knows the IP address of the virtual machine, the user can alsoaccess the virtual machine console using standard tools, such as Windows Terminal Services or Xterm.ConclusionVMware Infrastructure provides a simple architecture in the virtual environment to allow companies tomanage computing, storage, and networking resources without worrying about the underlying physicalhardware. VI architecture allows enterprises to create and configure their datacenters and reallocateresources to different priorities without the time delay and cost of reconfiguring their physical hardwareinfrastructure.With a suite of complementary virtualization and management services, such as VMware VMotion,VMware DRS, VMware HA, and VMware Consolidated Backup, VMware Infrastructure is the onlyproduct that provides a complete solution rather than a piecemeal approach to building datacenters in thevirtual environment.Hardware RequirementsVirtualCenter Server hardware must meet the following requirements:Processor . 2.0GHz or higher Intel or AMD x86 processor. Processor requirements can be larger if yourdatabase is run on the same hardware.Memory . 2GB RAM minimum. RAM requirements can be larger if your database is run on the samehardware.Disk storage . 560MB minimum, 2GB recommended. You must have 245MB free on the destination drivefor installation of the program, and you must have 315MB free on the drive containing your %temp%directory.MSDE disk requirements . The demonstration database requires up to 2GB free disk space to decompressthe installation archive. However, approximately 1.5GB of these files are deleted after the installation iscomplete.Networking . 10/100 Ethernet adapter minimum (Gigabit recommended).Scalability . A VirtualCenter Server configured with the hardware minimums can support 20 concurrentclients, 50 ESX Server hosts, and over 1000 virtual machines. A dual-processor VirtualCenter Server with3GB RAM can scale to 50 concurrent client connections, 100 ESX Server hosts, and over 2000 virtualmachines.VirtualCenter Server Software RequirementsThe VirtualCenter Server is supported as a service on the 32‐bit versions of these operating systems:Windows 2000 Server SP4 with Update Rollup 1 (Update Rollup 1 can be downloaded fromhttp://www.microsoft.com/windows2000/server/evaluation/news/bulletins/rollup.mspx)Windows XP Pro (at any SP level)Windows 2003 (all releases except 64-bit)Virtual enter 2.0 installation is not supported on 64‐bit operating systems.The Virtual enter installer requires Internet Explorer 5.5 or higher in order to run.
VirtualCenter Database RequirementsVirtual enter supports the following database formats:Microsoft SQL Server 2000 (SP 4 only)Oracle 9iR2, 10gR1 (versions 10.1.0.3 and higher only), and 10gR2Microsoft MSDE (not supported for production environments)Each database requires some configuration adjustments in addition to the basic installation.Virtual Infrastructure Client RequirementsVirtual Infrastructure Client Hardware RequirementsThe Virtual Infrastructure Client hardware must meet the following requirements:Processor . 266MHz or higher Intel or AMD x86 processor (500MHz recommended).Memory . 256MB RAM minimum, 512MB recommended. Disk Storage . 150MB free disk space required for basic installation. You must have 55MB free on thedestination drive for installation of the program, and you must have 100MB free on the drive containingyour %temp% directory.Networking . 10/100 Ethernet adapter (Gigabit recommended).Virtual Infrastructure Client Software RequirementsThe Virtual Infrastructure Client is designed for the 32‐bit versions of these operating systems:Windows 2000 Pro SP4Windows 2000 Server SP4Windows XP Pro (at any SP level)Windows 2003 (all releases except 64-bit)The Virtual Infrastructure Client requires the .NET framework 1.1 (included in installation if required).VirtualCenter VI Web Access RequirementsThe VI Web Access client is designed for these browsers:Windows . Internet Explorer 6.0 or higher, Netscape Navigator 7.0, Mozilla 1.X, Firefox 1.0.7 and higher.Linux . Netscape Navigator 7.0 or later, Mozilla 1.x, Firefox 1.0.7 and higher.License Server RequirementsThis section describes the license server requirements.License Server Hardware RequirementsThe license server hardware must meet the following requirements:Processor . 266MHz or higher Intel or AMD x86 processor.Memory . 256MB RAM minimum, 512MB recommended.Disk Storage . 25MB free disk space required for basic installation.Networking . 10/100 Ethernet adapter (Gigabit recommended).VMware recommends that you install the license server on the same machine as your VirtualCenter Serverto ensure connectivity.
License Server Software RequirementsThe license server software is supported on the 32‐bit versions of the following operating systems:Windows 2000 Server SP4Windows XP Pro (at any SP level)Windows 2003 (all releases except 64-bit)ESX Server RequirementsThis section discusses the minimum and maximum hardware configurations supported by ESX Serverversion 3.Minimum Server Hardware RequirementsYou need the following hardware and system resources to install and use ESX Server.At least two processors:1500 MHz Intel Xeon and later, or AMD Opteron (32-it mode) for ESX Server1500 MHz Intel Xeon and later, or AMD Opteron (32-it mode) for Virtual SMP.1500 MHz Intel Viiv or AMD A64 x2 dual-core processors1GB RAM minimum.One or more Ethernet controllers. Supported controllers include: Broadcom NetXtreme 570x Gigabitcontrollers Intel PRO/100 adaptersFor best performance and security, use separate Ethernet controllers for the service console and the virtualmachinesA SCSI adapter, Fibre Channel adapter, or internal RAID controller:Basic SCSI controllers are Adaptec Ultra‐160 and Ultra‐320, LSI Logic Fusion-MPT, and mostNCR/Symbios. SCSI controllers. RAID adapters supported are HP Smart Array, Dell PercRAID (Adaptec RAID and LSI MegaRAID), andIBM (Adaptec) ServeRAID controllers.Fibre Channel adapters supported are Emulex and QLogic host bus adapters (HBAs).A SCSI disk, Fibre Channel LUN, or RAID LUN with unpartitioned space. In a minimum configuration,this disk or RAID is shared between the service console and the virtual machines.For iSCSI, a disk attached to an iSCSI controller, such as the QLogic qla4010.ESX Server supports installing and booting from the following storage systems:IDE/ATA disk drives . Installing ESX Server on an IDE/ATA drive or IDE/ATA RAID is supported.However, you should ensure that your specific drive controller is included in the supported hardware.Storage of virtual machines is currently not supported on IDE/ATA drives or RAIDs. Virtual machinesmust be stored on VMFS partitions configured on a SCSI drive, a SCSI RAID, or a SAN.SCSI disk drives . SCSI disk drives are supported for installing ESX Server. They can also store virtualmachines on VMFS partitions.Storage area networks (SANs) . SANs are supported for installing ESX Server.They can also store virtual machines on VMFS partitions. For information about pre-installation andconfiguration tasks and known issues with installing and booting from SANs,
Enhanced Performance RecommendationsThe lists in previous sections suggest a basic ESX Server configuration. In practice, you can use multiplephysical disks, which can be SCSI disks, Fibre Channel LUNs, or RAID LUNs.Here are some recommendations for enhanced performance:RAM. Having sufficient RAM for all your virtual machines is important to achieving good performance.ESX Server hosts require more RAM than typical servers. An ESX Server host must be equipped withsufficient RAM to run concurrent virtual machines, plus run the service console.For example, operating four virtual machines with Red Hat Enterprise Linux orWindows XP requires your ESX Server host be equipped with over a gigabyte ofRAM for baseline performance:1024MB for the virtual machines (256MB minimum per operating system asrecommended by vendors × 4)272MB for the ESX Server service consoleRunning these example virtual machines with a more reasonable 512MB RAM requires the ESX Serverhost to be equipped with at least 2.2GB RAM.2048MB for the virtual machines (512MB × 4) 272MB for the ESX Server service consoleThese calculations do not take into account variable overhead memory for each virtual machine.Dedicated fast Ethernet adapters for virtual machines . Dedicated Gigabit Ethernet cards for virtualmachines, such as Intel PRO/1000 adapters, improve throughput to virtual machines with high networktraffic.Disk location . For best performance, all data used by your virtual machines should be on physical disksallocated to virtual machines. These physical disks should be large enough to hold disk images to be usedby all the virtual machines.VMFS3 partitioning . For best performance, use VI Client or VI Web Access to set up your VMFS3partitions rather than the ESX Server installer. Using VI Client or VI Web Access ensures that the startingsectors of partitions are 64K-aligned, which improves storage performance.Processors . Faster processors improve ESX Server performance. For certain workloads, larger cachesimprove ESX Server performance.Hardware compatibility . To ensure the best possible I/O performance and workload management,VMware ESX Server provides its own drivers for supported devices. Be sure that the devices you plan touse in your server are supported. For additional detail on I/O device compatibility, download the ESXServer I/O Compatibility Guide from the VMware Web site atMaximum Configuration for ESX ServerThis section describes the hardware maximums for an ESX Server host machine. (Do not confuse this witha list of virtual hardware supported by a virtual machine.)Storage16 host bus adapters (HBAs) per ESX Server system, with 15 targets per HBA128 logical unit numbers (LUNs) per storage array255 LUNs per ESX Server system32 paths to a LUNMaximum LUN ID: 255NOTE Although ESX Server supports up to 256 Fibre Channel LUNs for operation, theinstaller supports a maximum of 128 Fibre Channel SAN LUNs. If you have more than128 LUNs, connect them after the installation is complete.
Virtual Machine File System (VMFS)128 VMFS volumes per ESX Server systemMaximum physical extents per VMFS volume:VMFS-3 volumes: 32 physical extentsVMFS-2 volumes: 32 physical extents (VMFS‐2 volumes are read-only for ESX Server 3.0.)2TB per physical extentMaximum size per VMFS volume:VMFS-3 volumes: approximately 64TB, with a maximum of 2TB per physical extentVMFS-2 volumes: approximately 64TB, with a maximum of 2TB per physical extent (VMFS-2 volumesare read-only for ESX Server 3.0.) Maximum Sockets Maximum Cores Maximum ThreadsSingle core With hyperthreading 16 16 32,Without hyperthreading 16 16 16Dual core With hyperthreading 8 16 32 ,Without hyperthreading 16 32 32Virtual ProcessorsA total of 128 virtual processors in all virtual machines per ESX Server hostMemory64GB of RAM per ESX Server systemAdaptersUp to 64 adapters of all types, including storage and network adapters, per systemUp to 20 Gigabit Ethernet or 10/100 Ethernet ports per systemUp to 1024 ports per virtual switchVirtual Machine SpecificationsEach ESX Server machine can host up to 128 virtual CPUs in virtual machines (and up to 200 registeredvirtual machines), with the following capabilities and specifications.Virtual StorageUp to four host bus adapters per virtual machineUp to 15 targets per host bus adapterUp to 60 targets per virtual machine; 256 targets concurrently in all virtual machines per ESX Server hostVirtual SCSI DevicesUp to four virtual SCSI adapters per virtual machine, with up to 15 devices per adapter9TB per virtual diskVirtual ProcessorIntel Pentium II or later (dependent on system processor)One, two, or four processors per virtual machineNOTE All multiprocessor virtual machines require purchased licensing for VMware Virtual SMP for ESXServer. If you plan to create a two-processor virtual machine, your ESX Server machine must have at leasttwo physical processors. For a four-processor virtual machine, your ESX Server machine must have at leastfour physical processors.Virtual Chip Set Intel 440BX-based motherboard with NS338 SIO chip
Virtual BIOS Phoenix BIOS 4.0 Release 6Virtual Machine Memory Up to 16GB per virtual machineNOTE Windows NT as a guest supports only 3.444GB RAM.Virtual Adapters Up to six virtual PCI slots per virtual machineVirtual Ethernet Cards Up to four virtual Ethernet adapters per virtual machineNOTE Each virtual machine has a total of six virtual PCI slots, one of which is used by the graphicsadapter. The total number of virtual adapters, SCSI plus Ethernet, cannot be greater than six.Virtual Floppy Drives Up to two 1.44MB floppy drives per virtual machineVirtual CD Up to four drives per virtual machineLegacy Devices Virtual machines can also make use of the following legacy devices. However, forperformance reasons, use of these devices is not recommended.Virtual Serial (COM) Ports Up to four serial ports per virtual machineVirtual Parallel (LPT) Ports Up to three virtual LPT ports per virtual machineHost-Based License and Server-Based License ModesVirtual Center and ESX Server support two modes of licensing: license server-based and host-based. Inhost-based licensing mode, the license files are stored on individual ESX Server hosts. In license server-based licensing mode, licenses are stored on a license server, which makes these licenses available to oneor more hosts. You can run a mixed environment employing both host-based and license server-basedlicensing.Virtual Center and features that require Virtual Center, such as VMotion., must be licensed in licenseserver-based mode. ESX Server-specific features can be licensed in either license server-based or host-based mode.License Server-Based LicensingLicense: server-based licensing simplifies license management in large, dynamic environments by allowinga VMware license server to administer licenses. With license server-based licensing, you maintain all yourVirtual Center Management Server and ESX Server licenses from one console.Server-based licensing is based on industry-standard FlexNet mechanisms. With server-based licensing, alicense server manages a license pool, which is a central repository holding your entire licensedentitlement. When a host requires a particular licensed functionality, the license for that entitlement ischecked out from the license pool. License keys are released back to the pool when they are no longerbeing used and are available again to any host.The advantages of license server-based licensing include:You administer all licensing from a single location. New licenses are allocated and reallocated using any combination of ESX Server form factors. Forexample, you can use the same 32processor license for sixteen 2-processor hosts, eight 4-processor hosts,four 8-processor hosts, two 16-processor hosts, or any combination totaling 32 processors.Ongoing license management is simplified by allowing licenses to be assigned and reassigned as needed.Assignment changes as the needs of an environment change, such as when hosts are added or removed, orpremium features like VMotion, DRS, or HA are transferred among hosts.
During periods of license server unavailability, VirtualCenter Servers and ESX Server hosts using licenseserver-based licenses are unaffected for a 14-day grace period, relying on cached licensing configurations,even across reboots.VMware recommends using the license server-based licensing mode for large, changing environments.Host-Based LicensingThe host-based licensing mode is similar to the licensing mode of previous releases. With host-basedlicensing, your total entitlement for purchased features is divided on a per-machine basis, divided amongseparate license files residing on ESX Server hosts and the VirtualCenter Server.With host-based licensing, when someone activates a licensed feature, the feature for that entitlement mustreside in the license file on that host. With host-based licensing, you maintain separate license files on eachESX Server host. Distribution of unused licenses is not automatic, and there is no dependence on anexternal connection for licensing. Host-based license files are placed directly on individual ESX Serverhosts and replace the serial numbers used by previous versions of ESX Server version 2.x.The advantages of host-based licensing include:Host-based files require no license server to be installed for ESX Server host-only environments.In a VirtualCenter and license server environment, host-based licensing allows ESX Server host licenses tobe modified during periods of license server unavailability. For example, with host-based licensing you canmanually move virtual SMP license keys between hosts without a license server connection.By default, VirtualCenter and ESX Server software is configured to use TCP/IP ports 27000 and 27010 tocommunicate with the license server. If you did not use the default ports during license server installation,you must update the configuration on each ESX Server host.If you change the default ports for the license server, log on to the ESX Server host service console andopen the ports you want.To open a specific port in the service console firewall1 Log on to the service console as the root user.2 Execute this command:esxcfg-firewall --openport <portnumber>,tcpComponent – Attempted Action – During Grace Period -After Grace Period ExpiresVirtual machine Power on Permitted Not Permitted Create/delete Permitted Permitted Suspend/resume Permitted Permitted Configure virtual machine with VI Client Permitted PermittedESX Server host Continue operations Permitted Permitted Power on/power off Permitted Permitted Configure ESX Server host with VI Client Permitted Permitted Modify license file for host‐based licensing Permitted PermittedVirtual Center Remove an ESX Server host from inventory
(see next entry)Server Add an ESX Server host to inventory Not Permitted NotPermitted Connect/reconnect to an ESX Server host in Inventory Permitted Permitted Move a powered‐off virtual machine between hosts in inventory (cold migration) Permitted Permitted Move an ESX Server host among folders in inventory Permitted Permitted Move an ESX Server host out of a VMotion-DRS-HA cluster (see next entry) Permitted Permitted Move an ESX Server host intoa VMotion-DRS-HA cluster Not Permitted Not Permitted Configure VirtualCenter Server with VI Client Permitted Permitted Start VMotion between hosts in inventory Permitted Permitted Continue load balancing within a DRS cluster Permitted Permitted Restart virtual machines within the failed host.s HA cluster Permitted Not PermittedAny component Add or remove license keys Not Permitted Not Permitted Upgrade Not Permitted Not PermittedESX Server License TypesWhen you purchased your VMware Infrastructure software, you purchased one of three available editions,which are: VMware Infrastructure Starter edition . Provides virtualization for the small business and branch officeenvironments. Its limited production-oriented features include:NAS or local storageDeployable on a server with up to four physical CPUs and up to 8GB physical memory VMware Infrastructure Standard edition. Provides an enterprise-class virtualized infrastructure suitefor any workload. All standard functionality is enabled, and all optional add-on licenses (purchasedseparately) can be configured with this edition. Includes all production-oriented features, such as:
NAS, iSCSI, and SAN usageUp to four-way Virtual SMP VMware Infrastructure Enterprise edition. Provides an enterprise-class virtualized infrastructure suitefor the dynamic data center. It includes all the features of VMware Infrastructure Standard edition, and alsoincludes all optional add-on licenses.License Type Features for ESX Server MachinesFeature ESX Server Standard ESX Server StarterMaximum number of virtual machines Unlimited UnlimitedSAN support Yes Not availableiSCSI support Yes Not availableNAS support Yes YesVirtual SMP. support Yes Not availableVMware Consolidated Backup (VCB) Add-on1 Not availableComponents InstalledThe VMware VirtualCenter version 2 default installation includes the following components:VMware VirtualCenter Server . A Windows service to manage ESX Server hosts.Microsoft .NET Framework . Software used by the VirtualCenter Server, DatabaseUpgrade wizard, and the Virtual Infrastructure Client.VMware VI Web Access . A Web application to allow browser-based virtualmachine management.VMware Web Service . A software development kit (SDK) for VMware products.VMware license server . A Windows service allowing all VMware products to belicensed from a central pool and managed from one console.The last three components are optional if you select a custom setupport@hostname . for example, email@example.com@ip.address . for example, firstname.lastname@example.orgType a Web Service https port. The default is 443.Type a Web Service http port. The default is 80.Type a VirtualCenter diagnostic port. The default is 8083.Type a VirtualCenter port (the port which VirtualCenter uses to communicatewith the VI Client). The default is 902.Type a VirtualCenter heartbeat port. The default is 902.Select the check box if you want to maintain compatibility with the older SDKWeb interface.The default ports that VirtualCenter Server uses to listen for connections from the VI Client are ports 80and 902. VirtualCenter Server also uses port 443 to listen for data transfer from the VI Web Access Clientand other SDK clients.
The default port that VirtualCenter uses to send data to the managed hosts is port 902.Managed hosts also send a regular heartbeat over UDP port 902 to VirtualCenter Server. This port must notbe blocked by firewalls.Installing VMware ESX Server SoftwareTo create a boot partition, use the following settings:Mount Point . /bootFile System . ext3Size (MB) . VMware recommends 100MBAdditional Size Options . Fixed sizeTo create a swap partition, use the following settings:Mount Point . Not applicable. This drop-down menu is disabled when you select swap for file system.File System . swapSize (MB) . VMware recommends 544MB. For a guide to sizing, see the description of the swap partitionin.Additional size options . Fixed sizeTo create a root partition, use the following settings:Mount Point . / File System . ext3Size (MB) . VMware recommends at least 2560MB for the root partition, but you can fill the remainingcapacity of the drive. For a guide to sizing, see the description of the root partition in.Additional size options . Fixed size(Optional) To create a log partition (recommended), use the following settings:Mount Point . /var/logFile System . ext3Size (MB) . 500MB is the minimum size, but VMware recommends 2000MB for the log partitionNOTE If your ESX Server host has no network storage and one local disk, you must create two morerequired partitions on the local disk (for a total of five required partitions):vmkcore . A vmkcore partition is required to store core dumps for troubleshooting. VMware does notsupport ESX Server host configurations without a vmkcore partition.vmfs3 . A vmfs3 partition is required to store your virtual machines. These vmfs and vmkcore partitions arerequired on a local disk only if the ESX Server host has no network storage.Locating the Installation LogsAfter you install and reboot, log on to the service console to read the installation logs:/root/install.log is a complete log of the installation./root/anaconda-ks.cfg is a kickstart file containing the selected installation.Creating a Rescue Floppy Disk
Use dd, rawwritewin, or rawrite to create a floppy image called bootnet.img. This file is located on the ESXServer CD in the /images directory.Functional ComponentsThe functional components monitor and manage tasks. The functional components areavailable through a navigation button bar in the VI Client. The options are:Inventory – A view of all the monitored objects in Virtual Center. Monitored objects include datacenters,resource pools, clusters, networks, data stores, templates, hosts, and virtual machines.Scheduled tasks – A list of activities and a means to schedule those activities. This is available throughVirtual Center Server only.Events – A list of all the events that occur in the Virtual Center environment. Use the Navigation option todisplay all the events. Use an object-specific panel to display only the events relative to that object.Admin – A list of environment-level configuration options. The Admin option provides configurationaccess to Roles, Sessions, Licenses, Diagnostics, and System Logs. When connected to an ESX Server,only the Roles option appears.Maps – A visual representation of the status and structure of the VMware Infrastructure environment andthe relationships between managed objects. This includes hosts, networks, virtual machines, and datastores. This is available only through Virtual Center Server.Various information lists are generated and tracked by your Virtual InfrastructureClient activity:Tasks – These activities are scheduled or initiated manually. Tasks generate event messages that indicateany issues associated with the task.Events – Messages that report Virtual Infrastructure activity. Event messages are predefined in the product.Alarms – Specific notifications that occur in response to selected events. Some alarms are defined byproduct default. Additional alarms can be created and applied to selected inventory objects or all inventoryobjects.Logs – Stored reference information related to selected event messages. Logs are predefined in the product.You can configure whether selected logs are generated.Users and Groups – For VirtualCenter, users and groups are created and maintained through the Windowsdomain or Active Directory database. Users and groups are registered with VirtualCenter, or created andregistered with an ESX Server, through the process that assigns privileges.Roles – A set of access rights and privileges. There are selected default roles. You can also create roles andassign combinations of privileges to each role.SAN (storage area network) is a specialized high-speed network that connects computer systems, or hostservers, to high performance storage subsystems. The SAN components include host bus adapters (HBAs)in the host servers, switches that help route storage traffic, cables, storage processors (SPs), and storagedisk arrays.
A SAN topology with at least one switch present on the network forms a SAN fabric.To transfer traffic from host servers to shared storage, the SAN uses Fibre Channel (FC)protocol that packages SCSI commands into Fibre Channel frames.In the context of this document, a port is the connection from a device into the SAN.Each node in the SAN, a host, storage device, and fabric component, has one or more ports that connect itto the SAN. Ports can be identified in a number of ways:WWPN . World Wide Port Name. A globally unique identifier for a port which allows certain applicationsto access the port. The FC switches discover the WWPN of a device or host and assign a port address to thedevice.Port_ID (or port address) . Within the SAN, each port has a unique port ID that serves as the FC addressfor the port. This enables routing of data through the SAN to that port. The FC switches assign the port IDwhen the device logs into the fabric. The port ID is valid only while the device is logged on.When transferring data between the host server and storage, the SAN uses a multipathing technique.Multipathing allows you to have more than one physical path from the ESX Server host to a LUN on astorage array.If a default path or any component along the path.HBA, cable, switch port, or storage processor. fails, theserver selects another of the available paths. The process of detecting a failed path and switching to anotheris called path failover.Storage disk arrays can be of the following types:An active/active disk array, which allows access to the LUNs simultaneously through all the storageprocessors that are available without significant performance degradation. All the paths are active at alltimes (unless a path fails).An active/passive disk array, in which one SP is actively servicing a given LUN. The other SP acts asbackup for the LUN and may be actively servicing other LUN I/O. I/O can be sent only to an activeprocessor. If the primary storage processor fails, one of the secondary storage processors becomes active,either automatically or through administrator intervention.To restrict server access to storage arrays not allocated to that server, the SAN uses zoning. Typically,zones are created for each group of servers that access a shared group of storage devices and LUNs. Zonesdefine which HBAs can connect to which SPs. Devices outside a zone are not visible to the devices insidethe zone.Zoning is similar to LUN masking, which is commonly used for permission management. LUN masking isa process that makes a LUN available to some hosts and unavailable to other hosts. Usually, LUN maskingis performed at the SP or server level.Overview of Using ESX Server with SANSupport for QLogic and Emulex FC HBAs allows an ESX Server system to be connected to a SAN array.You can then use SAN array LUNs to store virtual machine configuration information and application data.Using ESX Server with a SAN improves flexibility, efficiency, and reliability. It also supports centralizedmanagementas well as failover and load balancing technologies.
Benefits of Using ESX Server with SANYou can store data redundantly and configure multiple FC fabrics eliminating a single point of failure.Your enterprise is not crippled when one datacenter becomes unavailable.ESX Server systems provide multipathing by default and automatically support it for every virtual machine.Using ESX Server systems extends failure resistance to the server. When you use SAN storage, allapplications can instantly be restarted after host failure.Using ESX Server with a SAN makes high availability and automatic load balancing affordable for moreapplications than if dedicated hardware were used to provide standby services.Because shared central storage is available, building virtual machine clusters that use MSCS becomespossible.If virtual machines are used as standby systems for existing physical servers, shared storage is essential anda SAN is the best solution.You can use the VMware VMotion capabilities to migrate virtual machines seamlessly from one host toanother.You can use VMware HA in conjunction with a SAN for a cold-standby solution that guarantees animmediate, automatic response.You can use VMware DRS to automatically migrate virtual machines from one host to another for loadbalancing. Because storage is on a SAN array, applications continue running seamlessly.If you use VMware DRS clusters, you can put an ESX Server host into maintenance mode to have thesystem migrate all running virtual machines to other ESX Server hosts. You can then perform upgrades orother maintenance operations.The transportability and encapsulation of VMware virtual machines complements the shared nature of SANstorage. When virtual machines are located on SAN-based storage, it becomes possible to shut down avirtual machine on one server and power it up on another server.or to suspend it on one server and resumeoperation on another server on the same network.in a matter of minutes. This allows you to migratecomputing resources while maintaining consistent shared access.Use CasesUsing ESX Server systems in conjunction (combination) with SAN is particularly effective for thefollowing tasks:Maintenance with zero downtime. When performing maintenance, you can use VMware DRS or VMotionto migrate virtual machines to other servers. If shared storage is on the SAN, you can perform maintenancewithout interruptions to the user.Load balancing. You can use VMotion explicitly or use VMware DRS to migrate virtual machines to otherhosts for load balancing. If shared storage is on a SAN, you can perform load balancing withoutinterruption to the user.Storage consolidation and simplification of storage layout . If you are working with multiple hosts, andeach host is running multiple virtual machines, the hosts. storage is no longer sufficient and externalstorage is needed. Choosing a SAN for external storage results in a simpler system architecture whilegiving you the other benefits listed in this section. You can start by reserving a large LUN and then allocate
portions to virtual machines as needed. LUN reservation and creation from the storage device needs tohappen only once.Disaster recovery . Having all data stored on a SAN can greatly facilitate remote storage of data backups.In addition, you can restart virtual machines on remote ESX Server hosts for recovery if one site iscompromised.Metadata UpdatesA VMFS holds files, directories, symbolic links, RDMs, and so on, and corresponding metadata for theseobjects. Metadata is accessed each time the attributes of a file are accessed or modified. These operationsinclude, but are not limited to:Creating, growing, or locking a file.Changing a file.s attributes.Powering a virtual machine on or off.Zoning and ESX ServerZoning provides access control in the SAN topology. Zoning defines which HBAs can connect to whichSPs. When a SAN is configured using zoning, the devices outside a zone are not visible to the devicesinside the zone.Zoning has the following effects:Reduces the number of targets and LUNs presented to an ESX Server system.Controls and isolates paths within a fabric.Can prevent non-ESX Server systems from seeing a particular storage system, andfrom possibly destroying ESX Server VMFS data.Can be used to separate different environments (for example, a test from a production environment).When you use zoning, keep in mind the following:ESX Server hosts that use shared storage for failover or load balancing must be in one zone.If you have a very large deployment, you might need to create separate zones for different areas offunctionality. For example, you can separate accounting from human resources.! It does not work well to create many small zones of, for example, two hosts with four virtual machineseach.NOTE Whether a virtual machine can run management software successfully depends on the storage arrayin question.NOTE Check with the storage array vendor for zoning best practices.Choosing Larger or Smaller LUNsDuring ESX Server installation, you are prompted to create partitions for your system.You need to plan how to set up storage for your ESX Server systems before you performinstallation.You can choose one of these approaches:Many LUNs with one VMFS volume on each LUNMany LUNs with a single VMFS volume spanning all LUNsYou can have at most one VMFS volume per LUN. You could, however, decide to use one large LUN ormultiple small LUNs.
You might want fewer, larger LUNs for the following reasons:More flexibility to create virtual machines without going back to the SAN administrator for more space.More flexibility for resizing virtual disks, doing snapshots, and so on.Fewer LUNs to identify and manage.You might want more, smaller LUNs for the following reasons:Less contention on each VMFS due to locking and SCSI reservation issues.Different applications might need different RAID characteristics.More flexibility (the multipathing policy and disk shares are set per LUN).Use of Microsoft Cluster Service, which requires that each cluster disk resource is in its own LUN.Choosing Virtual Machine LocationsWhen you.re working on optimizing performance for your virtual machines, storage location is animportant factor. There is always a trade-off between expensive storage that offers high performance andhigh availability and storage with lower cost and lower performance. Storage can be divided into differenttiers depending on a number of factors:High Tier . Offers high performance and high availability. May offer built-in snapshots to facilitatebackups and Point-in-Time (PiT) restorations. Supports replication, full SP redundancy, and fibre drives.Uses high-cost spindles.Mid Tier . Offers mid-range performance, lower availability, some SP redundancy, and SCSI drives. Mayoffer snapshots. Uses medium-cost spindles.Lower Tier . Offers low performance, little internal storage redundancy. Uses low end SCSI drives orSATA (serial low-cost spindles).Not all applications need to be on the highest performance, most available storage. at least not throughouttheir entire life cycle.Virtual Switch PoliciesYou can apply a set of vSwitch-wide policies by selecting the vSwitch at the top of thePorts tab and clicking Edit.To override any of these settings for a port group, select that port group and click Edit.Any changes to the vSwitch-wide configuration are applied to any of the port groupson that vSwitch except for those configuration options that have been overridden by theport group.The vSwitch policies consist of:! Layer 2 Security policy! Traffic Shaping policy! Load Balancing and Failover policyLayer 2 Security PolicyLayer 2 is the data link layer. The three elements of the Layer 2 Security policy are promiscuousmode, MAC address changes, and forged transmits.
In non-promiscuous mode, a guest adapter listens to traffic only on its own MACaddress. In promiscuous mode, it can listen to all the packets. By default, guest adapters are set tonon-promiscuous mode.Promiscuous ModeReject — Placing a guest adapter in promiscuous mode has no effect on which frames arereceived by the adapter. Accept — Placing a guest adapter in promiscuous mode causes it to detect all frames passed onthe vSwitch that are allowed under the VLAN policy for the port group that the adapter isconnected to.MAC Address ChangesReject — If you set the MAC Address Changes to Reject and the guest operating system changesthe MAC address of the adapter to anything other than what is in the .vmx configuration file, allinbound frames will be dropped.If the Guest OS changes the MAC address back to match the MAC address in the .vmxconfiguration file, inbound frames will be passed again.Accept — Changing the MAC address from the Guest OS has the intended effect: frames to thenew MAC address are received.Forged TransmitsReject — Any outbound frame with a source MAC address that is different from the onecurrently set on the adapter will be dropped.Accept — No filtering is performed and all outbound frames are passed.Traffic Shaping PolicyESX Server shapes traffic by establishing parameters for three outbound traffic characteristics:average bandwidth, burst size, and peak bandwidth. You can set values for these characteristicsthrough the VI Client, establishing a traffic shaping policy for each uplink adapter.Average Bandwidth establishes the number of bits per second to allow across the vSwitchaveraged over time—the allowed average load.Burst Size establishes the maximum number of bytes to allow in a burst. If a burst exceeds theburst size parameter, excess packets are queued for later transmission. If the queue is full, thepackets are dropped. When you specify values for these two characteristics, you indicate whatyou expect the vSwitch to handle during normal operation.Peak Bandwidth is the maximum bandwidth the vSwitch can absorb (take up) without droppingpackets. If traffic exceeds the peak bandwidth you establish, excess packets are queued for latertransmission after traffic on the connection has returned to the average and there are enoughspare cycles to handle the queued packets. If the queue is full, the packets are dropped. Even if
you have spare bandwidth because the connection has been idle, the peak bandwidth parameterlimits transmission to no more than peak until traffic returns to the allowed average load.Load Balancing — Specify how to choose an uplink.Route based on the originating port ID — Choose an uplink based on the virtual port where thetraffic entered the virtual switch.Route based on ip hash — Choose an uplink based on a hash of the source and destination IPaddresses of each packet. For non-IP packets, whatever is at those offsets is used to compute thehash.Route based on source MAC hash — Choose an uplink based on a hash of the source Ethernet.Use explicit failover order — Always use the highest order uplink from the list of Activeadapters which passes failover detection criteria.Network Failover Detection — Specify the method to use for failoverdetection.Link Status only – Relies solely (only) on the link status provided by the network adapter. Thisdetects failures, such as cable pulls and physical switch power failures, but not configurationerrors, such as a physical switch port being blocked by spanning tree or misconfigured to thewrong VLAN or cable pulls on the other side of a physical switch.Beacon Probing – Sends out and listens for beacon (signal) probes (search) on all NICs in theteam and uses this information, in addition to link status, to determine link failure. This detectsmany of the failures mentioned above that are not detected by link status alone.11.3. The ESX Server Boot ProcessSeveral boot loaders are used on Linux systems, such as the Grand Unified boot loader (GRUB)and the Linux Loader (LILO). ESX uses LILO as the boot loader and has system components thatexpect the presence of LILO as the boot loader, so dont replace LILO with another boot loader, oryour server may experience problems. The configuration parameters for the boot loader arecontained in /etc/lilo.conf in a human-readable format, but the actual boot loader is stored in abinary format on the boot sector of the default boot disk. This section explains the boot process ofESX Server, as well as how to load the VMkernel and configuration files.11.3.1. High-Level Boot Process for ESX ServerBIOS is executed on the server.BIOS launch LILO from the default boot drive.
LILO loads Linux Kernel for the Service Console.The Service Console launches VMkernel.MUI Server is started.Virtual machines can then be launched by VMkernel and managed through MUI.11.3.2. Detailed Boot ProcessAs you can see in Figure 11.3, esx is the default boot image that loads automatically after thetimeout period. This is actually configured in the /etc/lilo.conf file shown in Figure 11.4 on theline default=esx. The Linux kernel for the Service Console is loaded in the lowest part of memorywhen it is started and occupies the amount of memory specified during the installation of ESXServer. If you look at the line in the /etc/lilo.conf file shown in Figure 11.4 that readsappend="mem=272M cpci=0;*;1:*;2:*;3:*;6:*;". This shows that the Service Console occupies thefirst 272MB of memory on the server. Figure 11.5 shows a screen shot from the MUI where theReserved Memory is set in the Options|Startup Profile for the server.Using HA and DRS TogetherWhen HA performs failover and restarts virtual machines on different hosts, its first priority isthe immediate availability of all virtual machines. After the virtual machines have been restarted,those hosts on which they were powered on might be heavily loaded, while other hosts arecomparatively lightly loaded. HA uses the CPU and memory reservation to decide failover, whilethe actual usage might be higher. You can also set up affinity and anti-affinity rules in DRS todistribute virtual machines to help availability of critical resources. For example, you can use ananti-affinity rule to make sure two virtual machines running a critical application never run onthe same host. Using HA and DRS together combines’ automatic failover with load balancing.This combination can result in a fast rebalancing of virtual machines after HA has moved virtualmachines to different hosts. You can set up affinity and anti-affinity rules to start two or morevirtual machines preferentially on the same host (affinity) or on different hosts (anti-affinity).Using DRS Affinity RulesAfter you have created a DRS cluster, you can edit its properties to create rules that specifyaffinity. You can use these rules to determine that:DRS should try to keep certain virtual machines together on the same host (forexample, for performance reasons) (affinity).DRS should try to make sure that certain virtual machines are not together (forexample, for high availability). You might want to guarantee certain virtualmachines are always on different physical hosts. When there’s a problem with one host, youdon’t lose both virtual machines (anti-affinity).
Using CPU Affinity to Assign Virtual Machines to Specific ProcessorsAffinity means that you can restrict the assignment of virtual machines to a subset of theavailable processors in multiprocessor systems. You do so by specifying an affinity setting foreach virtual machine.VMware Workstation and its virtual computing technology have changed the way mostcompanies look at test environments, and in some cases, even production environments.However VMware Workstation isn’t the only technology that VMware has to offer. The companyalso offers GSX Server and now ESX Server as well. Lets look at how to best leverage thesetechnologies in your company.VMware WorkstationVMware Workstation uses virtual machine technology that is designed mostly for the poweruser. It allows you to run multiple operating systems on a single PC. The operating systems thatcan run under a VMware virtual machine can include Windows 2000, Windows XP, Windows2003 Server, Novell Netware, and Linux.After running through a simple installation of VMware Workstation, you have the ability toconfigure virtual machines within VMware’s interface. These virtual machines act and look justlike a real computer, except they sit inside a window.In addition, you can network these computers, join and disjoin them from a domain, connect tothe Internet and other networks from within them, and simulate whatever environment youchoose.On one of my computers, Ive used VMware Workstation to simulate an entire Windows 2003network with Windows XP clients. With this environment, I can test all of the Windows 2003product line for compatibility with my network, as well as study for my Windows Server 2003certification exams. In the past, I had to have at least three systems to be able to accomplish thiskind of testing. Now all I need is one computer, an Internet connection, and VMwareWorkstation.How does this work?VMware works simultaneously with your operating system to allow you to host multiple virtualmachines. It does this by allowing you to configure your virtual machines on the VMwarevirtualization layer. This layer lets you map your hardware to the virtual machines resourcesand have virtual machines mapped to your floppy drive, hard drive, CPU, etc. Inside each virtualmachine, you can create virtual hard disks and specify how much RAM you want to allocate toeach of your virtual machines. Plus, each virtual machine can have its own IP address, even if thesystem hardware has only one network adapter.In most of the environments Ive seen, VMware Workstation is typically used to configure testenvironments, software development testing, training classrooms, and technical support (tosimulate the environment of the user). Now that youve seen how the power user can useVMware, let’s examine how VMware can meet the enterprise server and mainframe needs ofyour company.
VMware GSX ServerI recently was given the opportunity to evaluate VMware GSX Server, and I was impressed byhow well it worked. VMware Workstation supports only one CPU and up to 1 GB of RAM. GSXServer supports 2 CPUs and up to 2 GB of RAM. GSX Server is very similar to Workstation inmost other ways, but one of its coolest features is the Remote Console that allows you to remotelymanage and access your virtual machine from anywhere on your network. In addition, its mucheasier to work with in a high availability configuration.While VMware Workstation is mostly used by a single user to run multiple instances of operatingsystems for testing and support purposes, GSX Server is often used for server consolidation byrunning virtual machines of server operating systems that simply appear to be stand-aloneservers to clients on the network.VMware ESX ServerVMware ESX Server is mainframe-class virtual machine software. This solution is typically usedby mainframe data centers and cutting-edge companies. Ive also seen this solution used bystartup companies. With ESX Server, you can do amazing things such as more extensive serverconsolidation and virtual machine clustering.How does it differ from GSX Server and VMware Workstation?With VMware Workstation and GSX Server, the software sits on top of a host operating systemsuch as Windows or Linux. With ESX Server, the software runs directly on the systemshardware, eliminating the need to install a base OS. In fact, ESX has its own OS. The softwarebasically runs on its own Linux kernel, and Linux is quite beneficial to know when working withthe product, although its not an absolute necessity.Installation of this product is quite basic. You place the CD in the tray of a system and boot fromthe CD. It runs you through a typical Linux installation. At the end of the install, youreinstructed to go to a separate machine and type in a specific Web address to access the virtualconsole of ESX Server. From there, youll configure your system and create virtual machines.With ESX Server, you can have up to 3.6 GB of RAM per virtual machine as well as highperformance network cards.How are companies using ESX Server?What I really like about this product is how companies are using it. For example, Ive seenstartups simply purchase a SAN and ESX Server and create their whole network using ESXServer. This includes the servers and workstations, which are accessed with thin clients.GSX Server is lightning fast, so you can’t tell the difference between real systems and its virtualsystems (if you have powerful hardware running GSX Server). Furthermore, Ive seen datacenters use ESX Server for hosting client environments and test environments. In the future, Ithink more companies will take advantage of ESX Server as part of their business strategy.Final analysisVirtual machine technology is becoming more and more mainstream in today’s IT marketplace.With the current trend toward consolidating servers, VMware is quickly making a place for itsproducts in the server room. Microsoft has even taken an interest in the virtual machine marketby buying Virtual PC. However, Microsofts product line doesn’t quite have the maturity of theVMware product line when it comes to providing enterprise-class server solutions.
VMWARE GSX doesn’t exist anymore. It is replaced by VMWARE Server which is free.VMWARE server is a free virtualization software that run on a Windows Server platform. Goodfor testing and smaller environmentsVMWARE ESX Is the Hypervisor from VMWARE.It has its own OS, so can not be installed upon Windows. But must be installed on the serveritself. It uses it own file system: VMFS.Has really nice features like Vmotion, HA and resource groups.The virtualization technology for the Enterprise.VMware ESX Server 2.0Server Hardware RequirementsFor information on supported hardware, download the VMware ESX Server HardwareCompatibility Guide from the VMware Web site at www.vmware.com/support/esx2.Minimum Server Requirements Two up to sixteen processors: Intel® 900MHz Pentium® III Xeon and above 512MB RAM minimum One or more Ethernet controllers. Supported controllers include: Broadcom® NetXtreme 570x Gigabit controllers Intel PRO/100 adapters Intel PRO/1000 adapters 3Com® 9xx based adapters Note: If ESX Server has two or more Ethernet controllers, for best performance and security, use separate Ethernet controllers for the service console and the virtual machines. A SCSI adapter, Fibre Channel adapter or internal RAID controller. The basic SCSI adapters supported are Adaptec®, LSI Logic and most NCR/Symbios SCSI adapters. The RAID adapters supported are HP® Smart Array, Dell® PercRAID (Adaptec RAID and LSI MegaRAID), ServeRAID and Mylex® RAID devices. The Fibre Channel adapters that are supported are Emulex and QLogic adapters. The supported SCSI controllers are Adaptec® Ultra-160 and Ultra-320, LSI Logic Fusion-MPT and most NCR/Symbios SCSI controllers. The supported RAID controllers are HP® Smart Array, Dell® PercRAID (Adaptec RAID and LSI MegaRAID), IBM® (Adaptec) ServeRAID and Mylex RAID controllers. The supported Fibre Channel adapters are Emulex and QLogic host-bus adapters (HBAs). A SCSI disk, Fibre Channel LUN or RAID LUN with unpartitioned space. In a minimum configuration, this disk or RAID is shared between the service console and the virtual machines. Note: To ensure the best possible performance, always use Fibre Channel cards in dedicated mode. We do not recommend sharing Fibre Channel cards between the service console and the virtual machines.Recommended for Enhanced Performance A second disk controller with one or more drives, dedicated to the virtual machines
Sufficient RAM for each virtual machine and the service console Dedicated Ethernet cards for network-sensitive virtual machinesThe lists above outline a basic configuration. In practice, you may use multiple physical disks,which may be SCSI disks, Fibre Channel LUNs or RAID LUNs. For best performance, all of thedata used by the virtual machines should be on the physical disks allocated to virtual machines.Therefore, these physical disks should be large enough to hold disk images that will be used byall the virtual machines.Similarly, you should provide enough RAM for all of the virtual machines plus the service console.For background on the service console, see Characteristics of the VMware Service Console. Fordetails on how to calculate the amount of RAM you need, see Sizing Memory on the Server.Note: To ensure the best possible I/O performance and workload management, VMware ESXServer provides its own drivers for supported devices. Be sure that the devices you plan to use inyour server are supported. For additional detail on I/O device compatibility, download the VMwareESX Server I/O Adapter Compatibility Guide from the VMware Web site atwww.vmware.com/support/esx2.ESX Server virtual machines can share a SCSI disk with the service console, but for enhanceddisk performance, you can configure the virtual machines to use a SCSI adapter and diskseparate from those used by the service console. You should make sure enough free disk spaceis available to install the guest operating system and applications for each virtual machine on thedisk that they will use.Maximum Physical Machine SpecificationsStorage 16 host bus adapters per ESX Server system 128 logical unit numbers (LUNs) per storage array 128 LUNs per ESX Server systemVMware File System (VMFS) 128 VMFS volumes per ESX Server system Maximum physical extents per VMFS volume: VMFS-2 volumes: 32 physical extents VMFS-1 volumes: 1 physical extent 2TB per physical extent Maximum size per VMFS volume: VMFS-2 volumes: approximately 64TB, with a maximum of 2TB per each physical extent VMFS-1 volumes: approximately 2 TBCPU 16 physical processors per system, with 8 virtual CPUs per processor 80 virtual CPUs in all virtual machines per ESX Server systemMemory 64GB of RAM per ESX Server system Up to 8 swap files, with a maximum file size of 64GB per swap fileAdapters 64 adapters of all types, including storage and network adapters, per system 16 Ethernet ports per system Up to 8 Gigabit Ethernet ports or up to 16 10/100 Ethernet ports per system Up to 32 virtual machines per virtual network device (vmnic or vmnet adapter)Remote Management Workstation RequirementsThe remote workstation is a Windows NT 4.0, Windows 2000, Windows XP or Linux system fromwhich you launch the VMware Remote Console and access the VMware Management Interface.
The VMware Remote Console runs as a standalone application. The VMware ManagementInterface uses a Web browser.Hardware Requirements Standard x86-based computer 266MHz or faster processor 64MB RAM minimum 10MB free disk space required for basic installationSoftware — Windows Remote Workstation Windows XP Professional Windows 2000 Professional, Server or Advanced Server Windows NT 4.0 Workstation or Server, Service Pack 6a The VMware Management Interface is designed for these browsers: Internet Explorer 5.5 or 6.0 (6.0 highly recommended for better performance) Netscape Navigator® 7.0 Mozilla 1.xSoftware — Linux Remote WorkstationCompatible with standard Linux distributions with glibc version 2 or higher and one of thefollowing: For single-processor systems: kernel 2.0.32 or higher in the 2.0.x series, kernel in the 2.2.x series or kernel in the 2.4.x series For multiprocessor systems: kernel in the 2.2.x series or kernel in the 2.4.x series The VMware Management Interface is designed for these browsers: Netscape Navigator 7.0 Mozilla 1.xSupported Guest Operating SystemsIn ESX Server 2.0, VMware Virtual SMP for ESX Server is supported on all of the following guestoperating systems marked SMP-capable for dual-virtual CPU configurations. Guest Operating System SMP-CapableWindows Server 2003 (Enterprise, Standard and Web Editions) YesWindows XP Professional (Service Pack 1) NoWindows 2000 Server (Service Pack 3 or 4) YesWindows 2000 Advanced Server (Service Pack 3 or 4) YesWindows NT 4.0 — Service Pack 6a NoRed Hat Linux 7.2 YesRed Hat Linux 7.3 and 8.0 NoRed Hat Linux 9.0 YesRed Hat Enterprise Linux (AS) 2.1 and 3.0 YesSuSE Linux 8.2 YesSuSE Linux Enterprise Server (SLES) 8 Yes
Novell NetWare 6.5 and 5.1 (Patch 6) NoVirtual Machine SpecificationsEach ESX Server machine can host up to 80 virtual CPUs in virtual machines (and up to 200registered virtual machines) on a single ESX Server or up to 8 virtual machines for each CPU,with the following capabilities and specifications.Virtual Storage 4 host bus adapters per virtual machine 15 targets per host bus adapter 60 targets per virtual machine; 256 targets concurrently in all virtual machinesVirtual Processor Intel Pentium II or later, (dependent on system processor) One or two processors per virtual machine. Note: If you plan to create a dual-virtual CPU virtual machine, then your ESX Server machine must have at least two physical processors and you must have purchased the VMware Virtual SMP for ESX Server product.Virtual Chip Set Intel 440BX-based motherboard with NS338 SIO chipVirtual BIOS PhoenixBIOS 4.0 Release 6Virtual Memory Up to 3.6GB per virtual machineVirtual SCSI Devices Up to four virtual SCSI adapters per virtual machine with up to 15 devices per adapter 9TB per virtual diskVirtual Ethernet Cards Up to four virtual Ethernet adapters per virtual machine Note: Each virtual machine has a total of 5 virtual PCI slots, therefore the total number of virtual adapters, SCSI plus Ethernet, cannot be greater than 5.Virtual Floppy Drives Up to two 1.44MB floppy drives per virtual machineVirtual CD-ROM Up to two drives per virtual machineLegacy DevicesVirtual machines may also make use of the following legacy devices. However, for performancereasons, use of these devices is not recommended.Virtual Serial (COM) Ports Up to two serial ports per virtual machineVirtual Parallel (LPT) Ports One LPT Port per virtual machineVMware Versions ComparedIn the past, VMware was just a single product. Now, you will find that there are a widevariety of VMware products to choose from. Because of this, it can be confusing which oneto choose. This article aims at helping you sort it all out by providing a quick review of allVMware products.With that, I will now list out the major VMWare products and provide my take on howthese products differ from one another.
ESX ServerVMware’s ESX server is at the highest end of features and price of all the VMware serverapplications. The ESX actually loads right on to “bare-metal” servers. Thus, there is no need tofirst load an underlying operating system prior to loading VMware ESX. What is unique aboutESX is that it comes with its own modified Linux Kernel called VMKernel (based on Red HatEnterprise Linux). One of the strongest features of VMware ESX server is its performance. Whenrunning on similar hardware, you can run twice as many virtual servers on ESX as you canVMware Server. ESX is now sold in a suite of products called VMware Infrastructure.Overview:Enterprise ClassHigh AvailabilityBetter ManageabilityUsed for enterprise applications like Oracle, SQL Server, clustered servers, and other criticalinfrastructure serversSupports 4-10+ virtual machines per servers, depending on hardwareSupports up to 32 physical CPU (and 128 virtual) and up to 64GB of RAMLoads directly on hardware with no need to load underlying operating system (because it usesthe VMKernel)VMWare ServerVMware’s Server is a FREE VMware virtualization product built for use in productionservers. Unlike ESX, VMware Server still uses the underlying host operating system. WithVMware Server, you loose the some of the functionality and performance of the ESX serverbut don’t have as great of price tag (its free!) For an organization starting with a singleVMware server and not anticipating drastic growth, VMware Server is for you. VMwareServer’s primary competition is Microsoft’s Virtual Server.Overview:Used for medium/small business workgroup serversExcellent for software development usesUsed for Intranet, utility, and workgroup application serversSupports 2-4+ virtual machines per servers, depending on hardwareSupports 2-16 CPU and up to 64GB of RAM (but limited by host OS)Runs on top of Linux or Windows ServerWorkstationVMware’s Workstation is for use on a client workstation. For example, say that I want to run bothWindows 2003 server and Linux Fedora Core 5 on my desktop workstation, which is runningWindows XP. VMware Workstation would be the program I would use to do this. This wouldallow me the flexibility to run these guest operating systems to test various applications andfeatures. I could also create snapshots of them to capture their configuration at a certain point intime and easily duplicate them to create other virtual machines (such as moving them to aVMware Server). Keep in mind that I would have to have a “beefy” workstation with lots ofRAM and CPU to keep up with the applications I am also running on my host operating system(Windows XP). Some people ask whether you could run Workstation on a “server” and just nothave to use VMware Server. The answer is that, while you can do this, you don’t want to becausethe server’s applications won’t perform well under load and neither will the multiple operatingsystems. You might ask why you would buy VMware workstation for $189 when VMware Server
is free. Many people would assume that Server is better and costs less. The answer is that theseVMware Workstation and VMware Server serve different purposes. VMware Server should beused to run test or production servers. On the other hand, VMware Workstation would be usedby testers and developers because of its powerful snapshot manager. This development andtesting also applies to IT professionals who want the ability to take multiple snapshots of theirvirtual systems and be able to jump forward and back in these snapshots. However, you do notwant to run production servers in VMware Workstation. In other words, both VMwareWorkstation and VMware Server have different purposes and should not be looked at ascompeting products.Overview:Runs on your desktop operating systemCosts $189Great for testing applications and developing softwareCan create new virtual machines, where VMware Player cannotSupport bridged, host only, or NAT network configurationsAbility to share folders between host OS and virtual machinesAccess to host devices like CD/DVD drives and USB devicesSnapshot manager allows multiple snapshots and ability to move forward and backwardsbetween themLog files should be used only when you are having trouble with a virtual machine.VMDK files – VMDK files are the actual hard drive for the virtual machine. Usually youwill specify that a virtual machine’s disk can grow as needed. In that case, the VMDK filewill be continually growing, up to a size of 2GB. After 2GB, subsequent VMDK files will becreated.VMEM – A VMEM file is a backup of the virtual machine’s paging file. It will only appear ifthe virtual machine is running, or if it has crashed.VMSN & VMSD files – these files are used for VMware snapshots. A VMSN file is used tostore the exact state of the virtual machine when the snapshot was taken. Using thissnapshot, you can then restore your machine to the same state as when the snapshot wastaken. A VMSD file stores information about snapshots (metadata). You’ll notice that thenames of these files match the names of the snapshots.NVRAM files – these files are the BIOS for the virtual machine. The VM must know howmany hard drives it has and other common BIOS settings. The NVRAM file is where thatBIOS information is stored.VMX files – a VMX file is the primary configuration file for a virtual machine. When youcreate a new virtual machine and answer questions about the operating system, disk sizes,and networking, those answers are stored in this file. As you can see from the screenshotbelow, a VMX file is actually a simple text file that can be edited with Notepad. Here is the“Windows XP Professional.vmx” file from the directory listing, above:What are all the files that are located in my virtual machines directory on the ESX server for?*.nvram file – This file contains the CMOS/BIOS for the VM. The BIOS is based off thePhoenix BIOS 4.0 Release 6 and is one of the most successful and widely used BIOS and iscompliant with all the major standards, including USB, PCI, ACPI, 1394, WfM and PC2001.
If the NVRAM file is deleted or missing it will automatically be re-created when the VM ispowered on. Any changes made to the BIOS via the Setup program (F2 at boot) will besaved in this file. This file is usually less then 10K in size and is not in a text format (binary).vmdk files – These are the disk files that are created for each virtual hard drive in your VM.There are 3 different types of files that use the vmdk extension, they are:• *–flat.vmdk file - This is the actual raw disk file that is created for each virtual hard drive.Almost all of a .vmdk files content is the virtual machines data, with a small portion allotted tovirtual machine overhead. This file will be roughly the same size as your virtual hard drive.• *.vmdk file – This isnt the file containing the raw data anymore. Instead it is the diskdescriptor file which describes the size and geometry of the virtual disk file. This file is in textformat and contains the name of the –flat.vmdk file for which it is associated with and also thehard drive adapter type, drive sectors, heads and cylinders, etc. One of these files will exist foreach virtual hard drive that is assigned to your virtual machine. You can tell which –flat.vmdkfile it is associated with by opening the file and looking at the Extent Description field.• *–delta.vmdk file - This is the differential file created when you take a snapshot of a VM (alsoknown as REDO log). When you snapshot a VM it stops writing to the base vmdk and startswriting changes to the snapshot delta file. The snapshot delta will initially be small and then startgrowing as changes are made to the base vmdk file, The delta file is a bitmap of the changes tothe base vmdk thus is can never grow larger than the base vmdk. A delta file will be created foreach snapshot that you create for a VM. These files are automatically deleted when the snapshotis deleted or reverted in snapshot manager.*.vmx file – This file is the primary configuration file for a virtual machine. When you create anew virtual machine and configure the hardware settings for it that information is stored in thisfile. This file is in text format and contains entries for the hard disk, network adapters, memory,CPU, ports, power options, etc. You can either edit these files directly if you know what to add oruse the Vmware GUI (Edit Settings on the VM) which will automatically update the file.*.vswp file – This is the VM swap file (earlier ESX versions had a per host swap file) and iscreated to allow for memory over commitment on a ESX server. The file is created when a VM ispowered on and deleted when it is powered off. By default when you create a VM the memoryreservation is set to zero, meaning no memory is reserved for the VM and it can potentially be100% overcommitted. As a result of this a vswp file is created equal to the amount of memorythat the VM is assigned minus the memory reservation that is configured for the VM. So a VMthat is configured with 2GB of memory will create a 2GB vswp file when it is powered on, if youset a memory reservation for 1GB, then it will only create a 1GB vswp file. If you specify a 2GBreservation then it creates a 0 byte file that it does not use. When you do specify a memoryreservation then physical RAM from the host will be reserved for the VM and not usable by anyother VM’s on that host. A VM will not use it vswp file as long as physical RAM is available onthe host. Once all physical RAM is used on the host by all its VM’s and it becomes overcommittedthen VM’s start to use their vswp files instead of physical memory. Since the vswp file is a diskfile it will affect the performance of the VM when this happens. If you specify a reservation andthe host doe’s not have enough physical RAM when the VM is powered on then the VM will notstart.*.vmss file – This file is created when a VM is put into Suspend (pause) mode and is used to save