When Citrix Systems ships version 4.1 of XenServer later this quarter, the company will include Provisioning Server for Datacenters 4.5, which will enable IT managers to stream OS images stored on networked storage either to a virtual machine or to a native physical box.
Provisioning Server will ship with XenServer Platinum edition, which joins the ranks of XenServer Express, Standard and Enterprise. With this premium functionality, Citrix will charge premium pricing as well: $5,000 for a dual-CPU license, compared with $2,600 for a two-socket XenServer Enterprise perpetual license.
Provisioning Server derives from streaming technology that Citrix obtained when it acquired Ardence in December 2006 and appears to offer relatively unique capabilities that poise Citrix for healthy rivalry with VMware Inc.According to Simon Crosby, CTO of the Citrix Virtualization and Management Division, Provisioning Server "takes a P2V [physical-to-virtual] of a native image and puts it in a VHD [virtual hard disk] file which gets stored anywhere on networked storage." That done, "Provisioning Sever remotely boots the server off the network onto a native or virtualized server." Supported virtualization platforms include Citrix XenServer, of course, but also VMware and -- eventually – Microsoft's Hyper-V.
Actually, said Brian Madden, an independent analyst focused on server-based computing, Provisioning Server does not actually perform a P2V migration of an image; rather, it enables any image to be booted off a network share. "Ardence doesn't care if it's physical or virtual," he said. But converting an OS image to run within a virtual machine does have its advantages, Madden said, since it normalizes device drivers, and removes hardware incompatibilities.Provisioning Server use cases
The most obvious use case for Provisioning Server is within a virtual desktop infrastructure (VDI) scenario, where its multicasting abilities allow it to simultaneously broadcast an image to multiple devices -- "up to 1,000 off a single VHD file," Crosby said. If such an estimation is true, the capability could be very useful for organizations that want to deploy VDI for large groups of end users. Further, once an OS is running, changes to its image are locally cached rather than written back to the root image, Crosby explained, helping to keep end users' desktops in a clean, consistent state, and minimizing the number of desktop images administrators need to maintain and store.
But Madden said that there are other use cases for Provisioning Server, not just VDI. "Sharing a disk image is useful if you have more than one computer of the same type," he said, whether it's a server or a desktop. In Madden's own practice, he has used Ardence technology to provision large Citrix Presentation Server environments, and Web server farms are another logical use case.
The functionality of Provisioning Server appears to be relatively unique to Citrix and is not directly duplicated by any single VMware product, Madden said. Through the use of storage-based snapshotting, VMware shops could conceivably replicate the benefits of Provisioning Server's single image desktops, but management of delta disks – where user changes are kept -- is still challenging, he said. In addition, the Ardence technology provides a lot of "logistical glue" that VMware does not. When it comes to wide-scale provisioning of OS images, VMware "just isn't there yet."
Citrix XenServer wrap-up
Other than Provisioning Server, XenServer 4.1 includes another key new feature: integration with storage vendor Network Appliance Inc.'s Data Ontap operating system via XenServer's Storage Deliver Services framework, allowing XenServer to exploit storage services like backup, replication, snapshotting, and clones included in NetApp storage devices.
"Unlike VMware, we don't use a clustered file system," like VMware's Virtual Machine File System, said Citrix's Crosby. Instead, XenServer presents an API that storage providers can "plug in to," allowing XenSource to rely on the array's native storage services. "We love it because it's less software for us to write, and because it doesn't break existing storage management processes."
Citrix has also rebranded and reorganized several product offerings. First and foremost, the venerable Citrix Presentation Server will be known as XenApp going forward. XenApp is also the super-brand for XenServer and the forthcoming XenDesktop. Also, XenApp et al. now also all fall under the "über-family brand" of Citrix Delivery Center, said Mick Hollison, vice president of the Delivery Systems Division at Citrix.
Finally, Citrix introduced a new product called Citrix Workflow Studio, a graphical orchestration layer that works across the XenApp, XenServer, XenDesktop, and NetScaler product lines. Written on a Microsoft Windows foundation using PowerShell, the product is designed for use largely by the Citrix channel, which will use it to "compose workflows on a graphical canvas," Hollison said. A technology preview edition will be available in the second quarter.
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