"We've found [the Advanced Edition] contains the features that cloud providers want who are building very large clouds based on XenServer," said Simon Crosby, CTO of Data Center and Cloud Division at Citrix. "The Advanced Edition comes after XenServer Free, and it adds all the memory optimizations, it adds high availability, and it is priced very affordably for folks who are building very large clouds with tens of thousands of servers."
XenServer 5.6 may also end a long running argument between Citrix and VMware. OK, maybe not end it, but perhaps reshape it a bit. The two virtualization companies have had words over the usefulness of a feature called "memory overcommitment" within an enterprise deployment. Part of the reason for the arguing was that VMware had already had the capability within ESX for quite some time, while Citrix is only now adding support for it.
With XenServer 5.6, Citrix adds support for Dynamic Memory Control, which increases performance by sharing unused memory across virtual machines. With it, users can increase the number of virtual machines per host by permitting the memory utilization of existing virtual machines to be compressed so that additional virtual machines can boot on the host server. As virtual machines on that host are powered off or migrated to other hosts, running virtual machines can then reclaim that unused physical host memory. Much like on VMware ESX, users will have to define minimum and maximum memory settings for virtual machines.
On top of the enhancements in the Free and Advanced editions, new capabilities have been added to the Enterprise Edition. The new integration and management functions of XenServer include role-based administration and snapshots-reverts; role-based administration improves virtual machine security by maintaining a tiered access structure, while snapshots and reverts allow virtual servers to be backed up and restored where both the disk and memory imaging are saved.
Citrix also added automated workload balancing, which maximizes and optimizes server performance by intelligently placing and rebalancing server workloads based on user-defined and set thresholds. In addition, you'll find a new host power management feature that extends existing workload balancing capabilities by consolidating virtual machines during off hours to fewer host servers and then reactivating and migrating them as demand picks up. This feature will help minimize data center power consumption and save money by helping organizations go green; it's also very much like VMware's Distributed Power Management feature found in vSphere.
The Platinum Edition extends the previous three editions and adds functionality -- in the form of StorageLink SiteRecovery and a self-service portal extension to Lab Manager -- to help administrators accelerate the delivery of IT services that drive the business. SiteRecovery provides an automated way to recover from a data center outage through a single console that leverages the native capabilities of a customer's existing storage array. The self-service portal enables IT to remain in control but offers employees more flexibility by giving them quick access to needed IT resources that have been preconfigured and approved, or by allowing them to create new virtual machine environments that go through a request submission for IT approval and build-out.