First look: VMware vSphere 4.1 keeps the virtualization crown

With scalability improvements, network and storage I/O control, and countless other enhancements, VMware continues to redefine the possibilities for server virtualization

VMware has never been a company to rest on its laurels, and the release of VMware vSphere 4.1 demonstrates its continued effort on extending the capabilities of virtualization. There are still a few bumps here and there, such as quirky HA configuration issues, but from my preliminary testing, it seems clear that the best virtualization solution available today just got better.

While significant features have been added to the new version, there is no sea change in terms of core functionality or administrative interfaces as we saw with the initial move to VMware vSphere 4.0. VMware has built on that base and added several enterprise-level features that will likely prove extremely handy to midrange and large-scale VMware-based infrastructures.

[ Also on InfoWorld: The six-core Intel Westmere CPU and server blade systems from Dell, HP, and IBM are primed for virtualization. See "InfoWorld review: Intel's Westmere struts its stuff" and "Blade server review: Dell, HP, and IBM battle for the virtual data center." ]

Scaling vSphere hosts, clusters, and data centers
First off, some numbers: VMware vSphere 4.1 can support up to 3,000 virtual machines per cluster and 1,000 hosts per vCenter server, both roughly three times the limits in vSphere 4.0. The number of virtual machines per data center now maxes out at 5,000, which is twice the previous limit. Those are some big numbers that affect only the big deployments, but they will greatly simplify administration at that level.

On top of the augmented scalability, VMware has added a pile of new features aimed at simplifying VM management. Some enhancements to the vCLI command-line interface allow for extra virtual machine controls, while some enhancements to the host profile capability permit finer-grained control over ESX servers. Host lockdown mode and host power management have also been improved. Virtual machine serial ports can now be accessed over the network, and you can leverage Active Directory to control authentication to the ESX hosts themselves, rather than relying on local authentication or other methods.

Plenty of other new features in 4.1 should have an immediate impact on VMware deployments. There's a new method of memory management that relies on compression over swap during low memory situations. Someone figured out it's faster to compress memory pages than swap those pages to disk. This carries some processing overhead, naturally, but with today's 6-, 8-, and 12-core CPUs, overhead is much less of an issue. By using memory compression, you can squeeze even more VMs on a single host.

Also, vSphere 4.1 boasts vMotion speed improvements, enhancements to Distributed Resource Scheduler's VM affinity rules, and updates to the Enhanced VMotion Compatibility processor support that now encompasses more CPUs. I can attest to the VMotion speedup, as I was able to conduct a wide variety of VMotion tasks that were faster on vSphere 4.1 than on vSphere 4.0.

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