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VMware vSphere Storage Appliance - Technical Whitepaper


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  • 1. vSphere Storage ®ApplianceTEC H N I C A L W H ITE PA P E Rv 1 . 0/ U P d AT E d J U N E 2 0 1 1
  • 2. vSphere Storage ApplianceTable of ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Architectural Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Managing and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 TECH N I C AL WH ITE PAPE R / 2
  • 3. vSphere Storage ApplianceIntroductionIn VMware vSphere™ 5.0 (“vSphere”), VMware is releasing a new software storage appliance to the marketcalled the vSphere® Storage Appliance (VSA). This appliance provides an alternative shared storage solution forsmall-to-medium business (SMB) customers who might not be in a position to purchase a SAN or NAS array fortheir virtual infrastructure. Without shared storage configured in a vSphere environment, customers have notbeen able to exploit the unique features available in vSphere 5.0, such as vSphere® High Availability (vSphereHA), vSphere® vMotion® (vMotion), and vSphere® Distributed Resource Scheduler (vSphere DRS). The VSA isdesigned to provide shared storage for everyone.This paper presents an overview of the VSA architecture, deployment of a VSA storage cluster, and basicmonitoring and managing.Architectural OverviewVSA can be deployed in a two-node or three-node configuration. Collectively, the two or three nodes in the VSAimplementation are known as a VSA storage cluster. Each VMware ESXi server has a VSA instance deployed to itas a virtual machine. The VSA instance will then use the available space on the local disk(s) of the VMware ESXiservers to present one mirrored NFS volume per VMware ESXi. The NFS volume is presented to all VMware ESXiservers in the datacenter.Each NFS datastore is a mirror, the source residing on one VSA (and thus, one VMware ESXi), and the targetresiding on a different VSA (and thus, a different VMware ESXi). Therefore, should one VSA (or one VMwareESXi) suffer a failure, the NFS datastore can still be presented, albeit from its mirror copy. This means that afailure in the cluster is transparent to any virtual machines running on that datastore. VSA VSA VSA vSphere vSphere vSphere VSA Manager vSphere Client NFS NFS NFSFigure 1 . Three-Member VSA ClusterThe VSA can be deployed in two configurations:• 3 x VMware ESXi 5.0 server configuration• 2 x VMware ESXi 5.0 server configurationThe two different configurations are identical in the way in which they present storage. The only difference is inthe way that they handle VSA storage cluster membership. The following section covers the details of a three-node and two-node VSA storage cluster. TECH N I C AL WH ITE PAPE R / 3
  • 4. vSphere Storage ApplianceThree-Node ConfigurationIn the three-node standard configuration, each node runs an instance of VSA. Each node presents a file systemvia NFS that is mirrored to one other file system on another VSA. To prevent any sort of split-brain scenario, thethree-node VSA configuration requires at least two nodes to be running in order to maintain a majority of nodes. vCenter Server VSA Manager Manage VSA Datastore 2 VSA VSA Datastore 1 Datastore 3 Volume 1 Volume 3 Volume 3 Volume 2 (Replica) (Replica) Volume 2 Volume 1 (Replica) VS VS A A AP AP AP P AP P VS P P OS OS A OS OS AP AP AP AP P P P P ES OS OS OS ES OS Xi Xi -1 AP -3 P ES OS Xi -2 VSA Cluster with 3 membersFigure 2. Three-Member VSA ClusterIn Figure 2, the three NFS datastores in the oval are NFS file systems. These file systems are presented as NFS datastores to the VMware ESXi servers in the cluster. TECH N I C AL WH ITE PAPE R / 4
  • 5. vSphere Storage ApplianceTwo-Node ConfigurationThe two-node VSA configuration uses a special VSA cluster service, which runs on theVMware vCenter Server. This behaves as a cluster member and is used to make sure that there is still a majorityof members in the cluster, should one VMware ESXi server VSA member fail. There is no storage associated withthe VSA cluster service. vCenter Server VSA Manager VSA Cluster Service Manage Volume 1 Volume 2 Volume 2 Volume 1 (Replica) (Replica) VSA VSA Datastore 1 Datastore 2 VS VS A A AP AP AP AP P P P P OS OS OS OS AP AP P P ES OS ES OS Xi Xi -1 -3 VSA Cluster with 2 membersFigure 3 . Two-Member VSA ClusterIn Figure 3, the VSA datastores in the oval are NFS file systems presented as shared storage to the VMware ESXi servers in the datacenter.VSA InstallationA VSA installation is started by installing the VSA manager software on an existing VMware vCenter Server.NOTE: In this release of VSA, an instance of VMware vCenter Server 5.0 can only manage a single VSA storagecluster.Once completed, a vSphere client is opened and pointed to the VMware vCenter Server, and the VSA managerplug-in is enabled. This creates a VSA manager tab in the vSphere client. The VSA manager tab then navigatesthe customer through the remaining installation steps. During the installation, a datacenter must be selected,after which a list of VMware ESXi servers in that datacenter is presented. The installer will check thecompatibility of each of these hosts to make sure they are suitable for VSA deployment. Out of the compatiblehosts, a maximum of three hosts can be selected to participate in the VSA storage cluster. If the hosts areunsuitable for any reason (for example, if hardware is not supported, or networking is not configured), the installerwill report it and will not enable the user to select that particular host.The installation process scans all of the local storage attached to the VMware ESXi host, and then makes plans touse space not currently in use by the VMware ESXi boot image for data storage. The user is warned in severalplaces that any existing data will be overwritten. Once this is complete, the storage is configured as a datastoreand exported to other members in the VSA storage cluster. TECH N I C AL WH ITE PAPE R / 5
  • 6. vSphere Storage ApplianceDuring the installation, the VSA installer does some additional housekeeping to enable the user to takemaximum advantage of the shared storage now available. First, the installer configures a vMotion networkbetween the nodes in the VSA storage cluster. This enables the user to initiate the vMotion process on anyvirtual machines configured to run on the hosts that make up the VSA storage cluster. The installer alsoautomatically builds a vSphere HA cluster covering the VMware ESXi hosts in the VSA storage cluster. Thisprotects any virtual machines running in these hosts. For environments with additional hosts in the vSpheredatacenter beyond the VSA storage cluster, the user can manually extend the vMotion network configurationand vSphere HA cluster configuration to encompass these hosts.Managing and MonitoringThe VSA manager UI enables administrators to view the status of all VSA instances and datastores in the VSAstorage cluster. The interface is integrated into VMware vCenter, giving it a familiar look and feel, and helps anadministrator to deploy, manage, and monitor VSA instances and the VSA storage cluster.First, we can look at the monitoring capabilities. At deployment time, each VSA will host a primary datastoreand a replica.Figure 4 presents a view of the VSA members, shown by clicking on the Appliances button in the center-leftposition of the window. In this example, it is a three-member configuration. By default, the VSA members arelabeled VSA-0, VSA-1, and VSA-2. The Hosted Datastores and Hosted Replicas columns show that each VSAmember continues to host a primary datastore and a replica. The user can also see which VMware ESXi server ishosting the VSA via the Host column.Finally, we can see that all the VSA members are Online via the Status column.By selecting a VSA member, additional properties are displayed in the lower half of the screen, including front-end/Management Network and the Back-End Network/features details.Figure 4. VSA Manager – VSAs View TECH N I C AL WH ITE PAPE R / 6
  • 7. vSphere Storage ApplianceA Datastores view and a Maps view are also available to assist administrators with monitoring the VSA cluster.The VSA supports the concept of the VSA maintenance mode, both for the individual VSA instances and for theVSA storage cluster as a whole. Maintenance mode enables administrators to take individual members or thewhole VSA storage cluster offline in a controlled and structured manner.To put the whole cluster into maintenance mode, select the Enter Maintenance Mode link in the VSA ClusterProperties highlighted in Figure 5.Figure 5. VSA Manager – Cluster Maintenance ModeNFS exports from the VSA members become inaccessible when the whole cluster is put into maintenance mode.The cluster is still up, but the NFS services and datastores are taken offline.An individual VSA member can also be placed into maintenance mode by selecting a member from theAppliances view, and then clicking the Enter Maintenance Mode link. This is not the same as the VMware ESXimaintenance mode or the vSphere DRS maintenance mode. Rather, it is a maintenance mode specific to VSAcluster members. These actions will shut down the VSA member. If the whole cluster is already in maintenancemode, no further action is necessary.The best practice for using the maintenance mode is to first put the whole cluster into maintenance mode, andthen to place individual members into maintenance mode. TECH N I C AL WH ITE PAPE R / 7
  • 8. vSphere Storage ApplianceWhen a VSA member is placed into maintenance mode, the following states will show up in the VSA Manager >VSAs view:Figure 6. VSA Manager – Maintenance Mode VSA StatusIn Figure 6, member VSA-0 has been placed into maintenance mode. VSA-0 was hosting the primary datastoreVSADs-1 and the replica for VSADs-0. However, since we placed this member into maintenance mode, anotherVSA member had to take over the export of the primary NFS datastore. In this case, it is VSADs-2, as shown in the Exported Datastores column. TECH N I C AL WH ITE PAPE R / 8
  • 9. vSphere Storage Appliance Conclusion VSA enables users to get the full range of vSphere features, including vSphere HA, vMotion, and vSphere DRS, without having to purchase a physical storage array to provide shared storage, making VSA a very cost-effective solution. VSA is very easy to deploy. Many of the configuration tasks, such as network setup and vSphere HA deployment, are done by the installer. The benefit here is that this product can be deployed by customers who might not be well versed in vSphere. It gives them a good first-time user experience. VSA is very resilient. If a VMware ESXi server that is hosting one of the VSAs goes down, or one VSA member suffers an outage, with the redundancy built into the VSA, the NFS share presented from that VSA will be automatically and seamlessly failed over to another VSA in the cluster. About the author: Cormac Hogan is a Senior Technical Marketing Manager responsible for storage in the Infrastructure Product Marketing group at VMware. His focus is on core vSphere storage and virtual storage in general, including VSA and other storage technologies. He was one of the first VMware employees at the EMEA headquarters in Cork, Ireland, in April 2005. He spent two years as the Technical Support Escalation Engineer for Storage before moving into a Support Readiness Training role, where he developed training materials and delivered training to technical support and VMware support partners.vMware, Inc. 3401 Hillview Avenue Palo Alto CA 94304 USA Tel 877-486-9273 Fax 650-427-5001 www .vmware .comCopyright © 2011 VMware, Inc. All rights reserved. This product is protected by U.S. and international copyright and intellectual property laws. VMware products are covered by one or more patents listed at VMware is a registered trademark or trademark of VMware, Inc. in the United States and/or other jurisdictions. All other marks and names mentioned herein may betrademarks of their respective companies. Item No: VMW-WP-vSPHR-STOR-APP-USLET-101