VMware Infrastructure 3 is a hard act to follow. When VI3 was released, it not only set the bar for all virtualisation solutions to follow, but was so polished that many shops put it into production immediately, with no ill effects.

This week's release of VMware Infrastructure 3.5 is intended to continue the trend of stable, function-rich releases from the leader in virtualisation. Based on what I've seen in the beta code I've been testing, it'll be a close call.

I've been running VI3.5 in the lab for weeks now, using the code provided from VMware's beta program. This includes the base products ESX Server 3.5, VirtualCenter 2.5 and the management client, as well as new features such as live storage migration and distributed power management. It also includes a bevy of new add-ons -- for example, an automated patch manager and a tool for capacity planning and physical-to-virtual (P2V) migration.

The big news for VI3.5 isn't the core functionality: VMotion, Distributed Resource Scheduler, High Availability and Consolidated Backup have been in customers' hands for more than a year now. There are a few little additions here, such as Cisco Discovery Protocol support on ESX hosts (which makes switch-port location trivial), but the larger story is in the management additions to the base packages.

Snap and patch

One of the most prominent of these is Update Manager, which is essentially an automated Windows and Linux patch application designed specifically for virtual machines (VM). It allows administrators quick and easy access to reports on outstanding security patches and bug fixes that apply to one or more VMs and lets them schedule the installation of those patches.

Update Manager traces its ancestry to Shavlik Technologies LLC's HFNetChk and functions in a similar fashion. The key difference is that Update Manager automatically takes a snapshot of the VM's current state before applying the update or patch, providing a safety net that is crucial for maintaining stability across a virtualised environment.

Update Manager also significantly eases some of the administration burden found in manual or outboard patch management systems. Applying patches to one or more VMs is as simple as selecting them and running through a wizard. Once that's done, it takes a snapshot of each VM, the updates are applied and the VM is rebooted.

If something has gone awry and the VM becomes unstable, it can be quickly restored to a known good state from that snapshot.

The length of time to retain these snapshots is also configurable, which reduces storage overhead while still providing a time-limited backup plan.

In the beta, this feature functioned reasonably well, although it seems to be more in tune to Windows patches than Linux patches, and it does raise some questions about automated patch installations on some Linux distributions. For instance, CentOS is essentially Red Hat Enterprise Linux without any branding or support, and it is technically unsupported on VMware. But Red Hat patches can be applied to CentOS systems, which may be problematic from a licensing standpoint.

The beta produced several interesting errors while running Update Manager, but no show-stoppers. It's a wide-ranging feature that could wreak havoc with an otherwise stable infrastructure if not closely controlled, but we'll have to wait for the released code to accurately gauge its stability and reliability.