Downloaded 21 times
![Increase application availability
Fast, automated recovery
automated failover/restart within a cluster
disaster recovery across sites
VM portability enables this to work reliably across
potentially different hardware configurations
Fault tolerance
hypervisor‐based fault tolerance against hardware
failures [Bressoud and Schneider, SOSP 1995]
run two identical VMs on two different machines,
backup VM takes over if primary VM’s hardware crashes
commercial prototypes beginning to emerge (2008)](https://image.slidesharecdn.com/is2111virtualization-140904003616-phpapp02/75/cloud-basics-13-2048.jpg)
![Example: CPUState
static struct {
uint32 GPR[16];
uint32 LR;
uint32 PC;
int IE;
int IRQ;
} CPUState;
void CPU_CLI(void)
{
CPUState.IE = 0;
}
void CPU_STI(void)
{
CPUState.IE = 1;
}
Goal for CPU virtualization techniques
Process normal instructions as fast as possible
Forward privileged instructions to emulation routines](https://image.slidesharecdn.com/is2111virtualization-140904003616-phpapp02/75/cloud-basics-37-2048.jpg)
More Related Content
cloud basics.
- 1.
- 2. What is Virtualization Virtualization is a technique of abstracting physical resources in to logical view Increases utilization and capability of IT resource Simplifies resource management by pooling and sharing resources Significantly reduce downtime Planned and unplanned Improved performance of IT resources
- 3. What is aVirtual Machine ?
- 9. Why Virtualize? Consolidateresources Server consolidation Client consolidation Improve system management For both hardware and software From the desktop to the data center Improve the software lifecycle Develop, debug, deploy and maintain applications in virtual machines Increase application availability Fast, automated recovery
- 10. Consolidate resources Serverconsolidation reduce number of servers reduce space, power and cooling 70•-80% reduction numbers cited in industry Client consolidation developers: test multiple OS versions, distributed application configurations on a single machine end user: Windows on Linux, Windows on Mac reduce physical desktop space, avoid managing multiple physical computers
- 11. Improve system management Data center management VM portability and live migration a key enabler automate resource scheduling across a pool of servers optimize for performance and/or power consumption allocate resources for new applications on the fly add/remove servers without application downtime Desktop management centralize management of desktop VM images automate deployment and patching of desktop VMs run desktop VMs on servers or on client machines Industry‐cited 10x increase in sys admin efficiency
- 12. Improve the softwarelifecycle •Develop, debug, deploy and maintain applications in virtual machines Power tool for software developers record/replay application execution deterministically trace application behavior online and offline model distributed hardware for multi‐tier applications Application and OS flexibility run any application or operating system Virtual appliances a complete, portable application execution environment
- 13. Increase application availability Fast, automated recovery automated failover/restart within a cluster disaster recovery across sites VM portability enables this to work reliably across potentially different hardware configurations Fault tolerance hypervisor‐based fault tolerance against hardware failures [Bressoud and Schneider, SOSP 1995] run two identical VMs on two different machines, backup VM takes over if primary VM’s hardware crashes commercial prototypes beginning to emerge (2008)
- 14. Virtualization Comes inMany Forms 14 Each application sees its own logical memory, independent of physical memory Virtual Memory Each application sees its own logical network, independent of physical network Virtual Networks Each application sees its own logical server, independent of physical servers Virtual Servers Each application sees its own logical storage, independent of physical storage Virtual Storage
- 15. 15 Memory Virtualization Each application sees its own logical memory, independent of physical memory Virtual Memory Benefits of Virtual Memory • Remove physical-memory limits • Run multiple applications at once Physical memory Swap space App App App
- 16. 16 Network Virtualization Each application sees its own logical network, independent of physical network Virtual Networks Benefits of Virtual Networks • Common network links with access-control properties of separate links •Manage logical networks instead of physical networks • Virtual SANs provide similar benefits for storage-area networks VLAN A VLAN B VLAN C Switch Switch VLAN trunk
- 17. Server Virtualization BeforeServer Virtualization: Application Operating system Single operating system image per machine Software and hardware tightly coupled Running multiple applications on same machine often creates conflict Underutilized resources After Server Virtualization: App App App Operating system App App App Operating system Virtualization layer Virtual Machines (VMs) break dependencies between operating system and hardware Manage operating system and application as single unit by encapsulating them into VMs Strong fault and security isolation Hardware-independent
- 18. Storage Virtualization Processof presenting a logical view of physical storage resources to hosts Logical storage appears and behaves as physical storage directly connected to host Examples of storage virtualization are: Host-based volume management LUN creation Tape virtualization Benefits of storage virtualization: Increased storage utilization Adding or deleting storage without affecting application’s availability Non-disruptive data migration Virtualization Layer Servers Heterogeneous Physical Storage
- 19. Definitions Virtualization Alayer mapping its visible interface and resources onto the interface and resources of the underlying layer or system on which it is implemented Purposes Abstraction – to simplify the use of the underlying resource (e.g., by removing details of the resource’s structure) Replication – to create multiple instances of the resource (e.g., to simplify management or allocation) Isolation – to separate the uses which clients make of the underlying resources (e.g., to improve security) Virtual Machine Monitor (VMM) A virtualization system that partitions a single physical “machine” into multiple virtual machines. Terminology Host – the machine and/or software on which the VMM is implemented Guest – the OS which executes under the control of the VMM
- 20. Properties of Classical Virtualization Equivalence = Fidelity Program running under a VMM should exhibit a behavior identical to that of running on the equivalent machine Efficiency = Performance A statistically dominant fraction of machine instructions may be executed without VMM intervention Resource Control = Safety VMM is in full control of virtualized resources Executed programs may not affect the system resources
- 22. Evolution of Softwaresolutions • 1st Generation: Full virtualization (Binary rewriting) – Software Based – VMware and Microsoft Time • 3rd Generation: Silicon-based (Hardware-assisted) virtualization – Unmodified guest – VMware and Xen on virtualization-aware hardware platforms • 2nd Generation: Paravirtualization – Cooperative virtualization – Modified guest – VMware, Xen Virtual Machine Virtual Machine … Dynamic Translation Operating System Hardware VM VM Hypervisor Hardware Virtual Machine Virtual Machine … Hardware Virtualization Logic Hypervisor … Server virtualization approaches
- 23. Full Virtualization •1st Generation offering of x86/x64 server virtualization • Dynamic binary translation – The emulation layer talks to an operating system which talks to the computer hardware – The guest OS doesn't see that it is used in an emulated environment • All of the hardware is emulated including the CPU • Two popular open source emulators are QEMU and Bochs Server virtualization approaches Virtual Machine Guest OS Device Drivers Emulated Hardware App. A App. B App. C Device Drivers Host OS Hardware
- 24. Para-Virtualization • TheGuest OS is modified and thus run kernel-level operations at Ring 1 (or 3) – the guest is fully aware of how to process privileged instructions – thus, privileged instruction translation by the VMM is no longer necessary – The guest operating system uses a specialized API to talk to the VMM and, in this way, execute the privileged instructions • The VMM is responsible for handling the virtualization requests and putting them to the hardware Virtual Machine Guest OS Server virtualization approaches App. A App. B App. C Device Drivers Specialized API Virtual Machine Monitor Device Drivers Hypervisor Hardware
- 25. Server virtualization approaches Hardware-assisted virtualization • The guest OS runs at ring 0 • The VMM uses processor extensions (such as Intel®-VT or AMD-V) to intercept and emulate privileged operations in the guest • Hardware-assisted virtualization removes many of the problems that make writing a VMM a challenge • The VMM runs in a more privileged ring than 0, a virtual -1 ring is created Virtual Machine Guest OS App. A App. B App. C Device Drivers Specialized API Virtual Machine Monitor Device Drivers Hypervisor Hardware
- 26. System-level Design Approaches Full virtualization (direct execution) Exact hardware exposed to OS Efficient execution OS runs unchanged Requires a “virtualizable” architecture Example: VMWare Paravirtualization OS modified to execute under VMM Requires porting OS code Execution overhead Necessary for some (popular) architectures (e.g., x86) Examples: Xen, Denali CS5204 – Operating Systems
- 28. CPU Background VirtualizationTechniques System ISA Virtualization Instruction Interpretation Trap and Emulate Binary Translation
- 29. Computer System Organization CPU MMU Memory Controller Local Bus Interface High-Speed I/O Bus NIC Controller Bridge Frame Buffer LAN Low-Speed I/O Bus CD-ROM USB
- 30. CPU Organization InstructionSet Architecture (ISA) Defines: the state visible to the programmer registers and memory the instruction that operate on the state ISA typically divided into 2 parts User ISA Primarily for computation System ISA Primarily for system resource management
- 31. User ISA -State User Virtual Memory Program Counter Condition Codes Reg 0 Reg 1 Reg n-1 FP 0 FP 1 FP n-1 Special-Purpose Registers General-Purpose Registers Floating Point Registers
- 32. User ISA –Instructions Integer Memory Control Flow Floating Point Add Sub And Compare … Load byte Load Word Store Multiple Push … Jump Jump equal Call Return … Add single Mult. double Sqrt double … Fetch Registers Issue Integer Integer Memory FP Typical Instruction Pipeline Decode Instruction Groupings
- 33. System ISA PrivilegeLevels Control Registers Traps and Interrupts Hardcoded Vectors Dispatch Table System Clock MMU Page Tables TLB I/O Device Access User Syste m User Extension Kernel Level 0 Level 1 Level 2
- 34. Outline CPU Background Virtualization Techniques System ISA Virtualization Instruction Interpretation Trap and Emulate Binary Translation
- 35. Isomorphism e(Si) SiSj Guest V(Si) V(Sj) e’(Si’) Si’ Sj’ Host Formally, virtualization involves the construction of an isomorphism from guest state to host state.
- 36. Virtualizing the SystemISA Hardware needed by monitor Ex: monitor must control real hardware interrupts Access to hardware would allow VM to compromise isolation boundaries Ex: access to MMU would allow VM to write any page So… All access to the virtual System ISA by the guest must be emulated by the monitor in software. System state kept in memory. System instructions are implemented as functions in the monitor.
- 37. Example: CPUState staticstruct { uint32 GPR[16]; uint32 LR; uint32 PC; int IE; int IRQ; } CPUState; void CPU_CLI(void) { CPUState.IE = 0; } void CPU_STI(void) { CPUState.IE = 1; } Goal for CPU virtualization techniques Process normal instructions as fast as possible Forward privileged instructions to emulation routines
- 38. Instruction Interpretation EmulateFetch/Decode/Execute pipeline in software Postives Easy to implement Minimal complexity Negatives Slow!
- 39. Trap and Emulate Guest OS + Applications Page Fault Unde f Instr vIRQ MMU Emulation CPU Emulation I/O Emulation Virtual Machine Monitor Privileged Unprivileged
- 40. CPU Architecture Whatis trap ? When CPU is running in user mode, some internal or external events, which need to be handled in kernel mode, take place. Then CPU will jump to hardware exception handler vector, and execute system operations in kernel mode. Trap types : System Call Invoked by application in user mode. For example, application ask OS for system IO. Hardware Interrupts Invoked by some hardware events in any mode. For example, hardware clock timer trigger event. Exception Invoked when unexpected error or system malfunction occur. For example, execute privilege instructions in user mode.
- 41. Trap and EmulateModel If we want CPU virtualization to be efficient, how should we implement the VMM ? We should make guest binaries run on CPU as fast as possible. Theoretically speaking, if we can run all guest binaries natively, there will NO overhead at all. But we cannot let guest OS handle everything, VMM should be able to control all hardware resources. Solution : Ring Compression Shift traditional OS from kernel mode(Ring 0) to user mode(Ring 1), and run VMM in kernel mode. Then VMM will be able to intercept all trapping event.
- 42. Trap and EmulateModel VMM virtualization paradigm (trap and emulate) : 1. Let normal instructions of guest OS run directly on processor in user mode. 2. When executing privileged instructions, hardware will make processor trap into the VMM. 3. The VMM emulates the effect of the privileged instructions for the guest OS and return to guest.
- 43. Trap and EmulateModel Traditional OS : When application invoke a system call : CPU will trap to interrupt handler vector in OS. CPU will switch to kernel mode (Ring 0) and execute OS instructions. When hardware event : Hardware will interrupt CPU execution, and jump to interrupt handler in OS.
- 44. Trap and EmulateModel VMM and Guest OS : System Call CPU will trap to interrupt handler vector of VMM. VMM jump back into guest OS. Hardware Interrupt Hardware make CPU trap to interrupt handler of VMM. VMM jump to corresponding interrupt handler of guest OS. Privilege Instruction Running privilege instructions in guest OS will be trapped to VMM for instruction emulation. After emulation, VMM jump back to guest OS.
- 45. De-privileging VMM emulatesthe effect on system/hardware resources of privileged instructions whose execution traps into the VMM aka trap-and-emulate Typically achieved by running GuestOS at a lower hardware priority level than the VMM Problematic on some architectures where privileged instructions do not trap when executed at deprivileged priority vmm resource privileged instruction GuestOS trap resource emulate change change
- 46. Issues with Trapand Emulate Not all architectures support it Trap costs may be high Monitor uses a privilege level Need to virtualize the protection levels
- 51. Binary Translator Guest Code Translator Translatio TC n Callouts Index Cache CPU Emulation Routines
- 57. Storage Virtualization Processof presenting a logical view of physical storage resources to hosts Logical storage appears and behaves as physical storage directly connected to host Examples of storage virtualization are: Host‐based volume management LUN creation Tape virtualization Benefits of storage virtualization: Increased storage utilization Adding or deleting storage without affecting application’s availability Non‐disruptive data migration
- 58. SNIA Storage VirtualizationTaxonomy Storage Virtualization Block Virtualization Disk Virtualization File System, File/record Virtualization Other Device Virtualization Tape, Tape Drive, Tape Library Virtualization Network Based Virtualization Storage Device/Storage Subsystem Virtualization Host Based Virtualization In-band Virtualization Out-of-band Virtualization What is created Where it is done How it is implemented
- 59. Storage Virtualization Requiresa Multi-Level Approach Server Storage Network Storage Path management Volume management Replication Path redirection Load balancing - ISL trucking Access control - Zoning Volume management - LUNs Access control Replication RAID
- 60. server With traditionalstorage hardware devices that connected directly to servers, the actual magnetic disk was presented to servers and their operating systems as LUNs, where the disk was arranged into sectors comprised of a number of fixed size blocks. To allow applications to not only store, but find information easily, the operating system arranged these blocks into a “filesystem” Much like a paper• based filing system, a file system is simply a logical way of referencing these blocks into a series of unique files, each with a meaningful name and type so they can be easily accessed.
- 61. Storage Network Network‐basedstorage virtualization embeds the intelligence, managing the storage resources in the networklayer. Abstracting the view of real storage resources between the server and the storage array , either in‐band or out‐of‐band.
- 62. Storage Virtualization Configuration Servers Storage Network Storage Arrays Virtualization Appliance Out-of-Band (a) Servers Storage Network Storage Arrays In-Band (b) Virtualization Appliance (a) In out-of-band implementation, the virtualized environment configuration is stored external to the data path (b) The in-band implementation places the virtualization function in the data path
- 63. In-Band-Approach The in‐bandapproach, sometimes referred to as symmetric. It embeds the virtualization functionality in the I/O (input/output) path between the server and storage array. It can be implemented in the SAN switches themselves.
- 65. In-Band-Approach All I/Orequests, along with the data, pass through the device, with the server interacting with the virtualization device, never directly with the storage device. The virtualization device analyzes the request, consults its mappingtables, and, inturn, performs I/O to the storage device. These devices not only translate storage requests but are also able to cache data with the iron‐board memory.
- 66. It also provides Metrics on data Usage Manage replication services Orchestrate data migration Implement thin provisioning.
- 67. Out-Of-Band Approach Theout‐of‐band approach, sometimes referred to as asymmetric It does not strictly reside in the I/O path like the in‐band approach. The servers maintain direct interaction with the storage array through the intelligent switch. The out‐of‐band appliance maintains a map (often referred to as meta‐data ) of all the storage resources connected in the SAN and instructs the server where to find it.
- 69. Out-Of-Band Approach •Ituses special software or an agent, as instructions need to be sent through the SAN to make it work. Functions such as caching of data are not possible. However, only the in‐band approach increased performance.
- 70. Pros and Cons Both in‐band and out‐of‐band approaches provide virtualization with the ability to: 1. Pool heterogeneous vendor storage products in a seamless accessible pool. 2.Perform replication between non‐like devices. 3.Provide a single management interface
- 71. Pros and Cons Implementation can be very complex because the pooling of storage requires the storage extents to be remapped into virtual extents. Clustering is needed to protect the mapping tables and maintain cache consistency which can be very risky. The I/O can suffer from latency, impacting performance and scalability due to the multiple steps required to complete the request
- 72. Pros and Cons Decoupling the virtualization from the storage once it has been implemented is impossible because all the meta‐data resides in the appliance. Solutions on the market only exist for fibrechannel (FC) based SANs. These devices are not suitable for Internet protocol (IP) based SANs. Since both approaches are dependent on the SAN, they require additional switch ports, which involves additional zoning complexity
- 73. Pros and Cons When migrating data between storage systems, the virtualization appliance must read and write the data through the SAN, check status coming back, and maintain a log for any changes during the move that impact performance. Specialized software needs to be installed on all servers , making it difficult to maintain.
- 74. Storage controller Enterprise‐classstorage arrays, which have features and capability suitable for large organizations, have always featured virtualization capabilities (some more than others) to enhance the physical storage resource. One example of this is RAID, for providing data protection from disk failures
- 75. Storage controller Manyenterprise‐class devices incorporate sophisticated switching architectures. with multiple physical connections to disk drives. The external storage assets presented to it are then “discovered” and managed in the same way as internal disks
- 76. Storage controller Thisapproach has a number of benefits, including not requiring a remapping of LUNs and increasing extents. Once virtualized in this manner, the sophisticated microcode software that resides on the storage controller presents the external storage.
- 77. Controller‐based storage virtualizationallows external storage to appear as if it’s internal.
- 78. Storage controller Leveragingmature enterprise class features, data can be migrated non•-disruptively from one pool to another, and replication can take place between non•- like and like storage. Partitioning can be implemented to allocate resources such as ports, cache, and disk pools to particular workloads
- 79. Advantages Capabilities suchas replication, partitioning, migration, and thin provisioning are extended to legacy storage arrays. Heterogeneous data replication between non•-like vendors or different storage classes reduces data protection costs. Interoperability issues are reduced as the virtualized controller mimics a server connection to external storage
- 80. Block-Level Storage Virtualization Ties together multiple independent storage arrays Presented to host as a single storage device Mapping used to redirect I/O on this device to underlying physical arrays Deployed in a SAN environment Non-disruptive data mobility and data migration Enable significant cost and resource optimization Servers Virtualization Applied at SAN Level Heterogeneous Storage Arrays
- 81. File-Level Virtualization BeforeFile-Level Virtualization Clients Clients IP Network Storage Array File Server NAS Devices/Platforms File Server Every NAS device is an independent entity, physically and logically Underutilized storage resources Downtime caused by data migrations After File-Level Virtualization Clients Clients IP Network Storage Array File Server NAS Devices/Platforms Virtualization Appliance File Server Break dependencies between end-user access and data location Storage utilization is optimized Nondisruptive migrations
- 82. Storage Virtualization Challenges Scalability Ensure storage devices perform appropriate requirements Functionality Virtualized environment must provide same or better functionality Must continue to leverage existing functionality on arrays Manageability Virtualization device breaks end-to-end view of storage infrastructure Must integrate existing management tools Support Interoperability in multivendor environment
- 84. Network Virtualization forDummies Making a physical network appear as multiple logical ones
- 85. Why Virtualize ? Internet is almost ossified Lots of band-aids and makeshift solutions (e.g. overlays) new architecture (aka clean-slate) is needed Hard to come up with a one-size-fits-all architecture Almost impossible to predict what future might unleash Why not create an all-sizes-fit-into-one instead! Open and expandable architecture Testbed for future networking architectures and protocols
- 86. Related Concepts VirtualPrivate Networks (VPN) Virtual network connecting distributed sites Not customizable enough Active and Programmable Networks Customized network functionalities Programmable interfaces and active codes Overlay Networks Application layer virtual networks Not flexible enough
- 87. Network Virtualization Model Business Model Architecture Design Principles Design Goals
- 88.
- 89.
- 90.
- 91. Design Goals Flexibility Service providers can choose arbitrary network topology, routing and forwarding functionalities, customized control and data planes No need for co-ordination with others IPv6 fiasco should never happen again Manageability Clear separation of policy from mechanism Defined accountabilityof infrastructure and service providers Modular management
- 92. Design Goals Scalability Maximize the number of co-existing virtual networks Increase resource utilization and amortize CAPEX and OPEX Security, Privacy, and Isolation Complete isolation between virtual networks Logical and resource Isolate faults, bugs, and misconfigurations Secured and private
- 93. Design Goals Programmability Of network elements e.g. routers Answer “How much”and “how” Easy and effective without being vulnerable to threats Heterogeneity Networking technologies Optical, sensor, wireless etc. Virtual networks
- 94. Design Goals Experimentaland Deployment Facility PlanetLab, GENI, VINI Directly deploy services in real world from the testing phase Legacy Support Consider the existing Internet as a member of the collection of multiple virtual Internets Very important to keep all concerned parties satisfied
- 95. Existing Projects Fourgeneral categories 1.Networking technology IP (X-Bone), ATM (Tempest) 2.Layer of virtualization Physical layer (UCLP), Application layer (VIOLIN) 3.Architectural domain Network resource management (VNRMS), Spawning networks (Genesis) 4.Level of virtualization Node virtualization (PlanetLab), Full virtualization (Cabo)