XenDesktop 7 on Hyper-V 2012
XenDesktop 7 is the latest product release from Citrix for delivering virtual desktops and applications allowing users to work from anywhere on any device. XenDesktop 7 is supported on all the major hypervisors; however I will present the case for selecting Hyper-V 2012. Please note, that this will not be a Hyper-V versus VMware or XenServer hypervisor comparison. Each hypervisor offers unique features that organizations will have to decide which is most important to them. However Hyper-V 2012 offers some great enhancements over Hyper-V 2008 R2 for XenDesktop 7 deployments.
1. Support for Windows 8 and Windows 2012 Virtual Machines
Hyper-V 2012 supports Windows 8 and Windows 2012 virtual machines. This may not be important for organizations with existing Windows 7 VDI deployments, but those running Windows XP should take notice. Microsoft has announced that all support for Windows XP will end next year on April 8, 2014. As of April 2013, NetMarketShare research shows that Windows XP is the second most widely used desktop operating system for businesses with 38% of the market share. Windows 7 is in first place with 44% market share.
NetMarketShare research also shows that over a period from Sept 2012 to April 2013, Windows 7 market share has remained steadfast at 44%. Windows XP market share has declined from 41% to 38%, while Windows 8 grew from 0.8% to 3%. If the current trend continues, most organizations with Windows XP VDI deployments will be migrating to Windows 8. XenDesktop 7 will support all versions of Windows desktops from Windows XP to Windows 8, so organizations can leverage it for migrations, and continue to support legacy applications that won’t run on Windows 8.
2. SMB 3.0 Enhancements
The Server Message Block (SMB) protocol is used for file sharing in Windows. In Windows Server 2012, the SMB protocol has been updated with new features to improve performance and stability. Some of these new features have a direct impact on the performance of Provisioning Services (PVS) and Machine Creation Services (MCS).
SMB Direct is a new transport protocol which supports network adapters that have Remote Direct Memory Access (RDMA) capability. This enables direct memory-to-memory data transfers between servers, with minimal CPU utilization, and low latency. To Hyper-V 2012 hosts, remote file servers appear as fast as local storage. By minimizing CPU utilization Hyper-V is able to allocate more CPU cycles to virtual machines and applications.
SMB Multichannel is a new feature that enables bandwidth aggregation through multiple network interfaces. This improves Machine Creation Services performance when virtual machines are placed on file shares with clustered shared volumes using SMB 3.0.
SMB Transparent Failover is another new feature that enables Windows file shares in a Failover Cluster configuration to be continuously available. A good example of this would be if a Provisioning Services vDisk is placed on a file share in the cluster. If a failure occurs on the node, the SMB client on the Provisioning server will reconnect to another file server node in the cluster automatically and Provisioning Services does not experience any downtime.
For a more in depth look at the new SMB 3.0 features please see the Microsoft TechEd 2013 session Understanding the Hyper-V over SMB Scenario, Configurations, and End-to-End Performance presented by Jose Barreto.
3. Scalability Improvements
Hyper-V 2012 resources scale about 4-16 times higher than Hyper-V 2008 R2. A Hyper-V 2012 host can support up to 320 logical processors, whereas a Hyper-V 2008 R2 host supports 64. A Hyper-V 2012 host can support up to 4TB of RAM, whereas Hyper-V 2008 R2 supports 1TB. A Hyper-V 2012 cluster can support up to 64 nodes, which goes well beyond the 16 node limitation of Hyper-V 2008 R2. For large XenDesktop deployments with adequately sized servers, this will mean fewer hardware resources required in the datacenter to support the environment. See the chart below from Microsoft’s whitepaper on Windows Server 2012 to see other resource improvements made to Hyper-V 2012.
4. Live Migration No Longer Restricted to Clusters
In Hyper-V 2008 R2, Live Migration was only possible between nodes in a cluster. With Hyper-V 2012, it is now possible to “live migrate” between two standalone Hyper-V hosts, or between two stand-alone Hyper-V host clusters. The file shares in the storage locations must be using SMB 3.0 in order to take advantage of this feature. This is useful for smaller XenDesktop environments where resources may be limited and dedicating host servers to a cluster may not be feasible, or in test environments where building a cluster is not warranted.
5. Networking Enhancements
There have been several networking enhancements added in Windows Server 2012 and Hyper-V 2012.