The Excalibur Technology Preview provides an early glimpse at some of the upcoming improvements to XenApp and XenDesktop. While the unification of XenDesktop and XenApp into a single deployment and management architecture and the added support for the next generation Windows operating systems are undoubtedly the most obvious changes, we’ve made a number of other improvements throughout the product. Among those are improvements to both the Machine Creation Services (MCS) and Provisioning Services (PVS) features.
Provisioning for XenApp Servers via MCS or PVS
One of the benefits of the updated FlexCast Management Architecture is that XenApp farms can now be deployed and managed from within Studio. This also means they can be provisioned using the Machine Creation Services linked-clone delivery model that has been available within XenDesktop for a few releases now. One of the primary benefits of MCS is the ease in which new catalogs of machines (virtual desktops and now virtual XenApp servers) can be created. Updates to the catalog creation wizards in Studio guide you though the initial roll-out of a virtual XenApp farm. The MCS model provides many of the same single image management benefits of Provisioning Services, but works directly on the storage managed by your hypervisor, so there is no need to deal with PXE or build-out a Provisioning Services deployment. However, this capability is limited to the new Excalibur version of XenApp.
PVS streaming for XenApp farms and desktop catalogs is still an option in Excalibur, providing the enhanced image management capabilities and storage IO optimizations beneficial in larger, more complex environments, though management of the Provisioning Services infrastructure remains in a separate management console. Provisioning Services will continue to provide a centralized image library for mixed environments where multiple “sites” or “farms” of XenDesktop and XenApp are used.
Support for New Windows Server 2012 and Hyper-V Storage Capabilities
Windows Server 2012 and Hyper-V version 3 add new and improved facilities for accessing storage for virtual machines, and you can try out some of these features in the Excalibur Tech Preview with both PVS and MCS.
Hyper-V version 3 adds support for a new virtual disk format, VHDX. The new format solves some of the performance and alignment issues of the VHD/AVHD formats. MCS catalogs created on Windows Server 2012 / Hyper-V 3 hosts will automatically leverage this new format. Likewise, secondary disks attached to VMs for PVS write caches or Personal vDisks will leverage VHDX. Provisioning Services vDisks, which are accessed and managed directly from the PVS servers themselves will continue to use the base VHD format since you can still run PVS servers on Windows Server 2008 R2.
Another new feature in Hyper-V 3 is the support for Clustered Shared Volume (CSV) read caching. This capability is built into the failover clustering mechanism in Windows Server and allows clusters of Hyper-V 3 hosts to use host RAM as a read cache for virtual machine disks (VHDX files) on block storage. In Excalibur we can take advantage of this capability to reduce storage IO for MCS catalogs during boot and logon storms. The effect is similar to that of the caching that takes place on PVS hosts, except that the blocks are delivered once to each Hyper-V host and then shared among the VMs on that host. CSV cashing makes use of host RAM for this cache so there will be some trade off between cache size and the amount of RAM available to VM’s.
Bottom line? There are some great enhancements to the Hyper-V platform in Windows Server 2012 and Excalibur takes good advantage of them to deliver a combined solution that is robust, cost-effective, and scalable.
More to Come
The Excalibur Technology Preview features some, but not all, of the enhancements to provisioning currently being developed. Some of the other improvements we are working on include: MCS support for KMS, support for Windows Server 2012 SMB 3 storage, and a some significant performance and usability improvements in the PVS image capture and catalog creation tools. Stay tuned…