Patching, backing up and troubleshooting virtual machines : Necessary evils

The first three parts of this series have covered planning, building and securing a virtual environment. In this final part of the series, we cover how to patch, back up and troubleshoot your virtual machines (VMs) and virtualization environment.

Patching and updating virtual machines
Ignore patching and updates at your own peril. Software patches and upgrades are necessary to resolve bugs and security vulnerabilities and to update software with new features. With virtual hosts, it is even more important to apply patches in a timely manner because a bug or vulnerability can affect many virtual machines on that host. Each virtualization vendor has a different patch schedule, so be aware of them, and sign up for alerts when new patches are released. Pay special attention to security patches, and apply them as quickly as possible. You should establish a regular patch routine, and after patches and updates have been released, don't delay in applying them in your environment.

In addition, virtual environments offer some advantages, such as the snapshot feature that can provide an easy recovery point for any patches that cause problems on virtual machines. So you should look for patching systems that are designed to work with virtual hosts and virtual machines.

For more on launching a virtual deployment: Virtualization deployment: The assessment and planning phases Building and configuring in a virtualization deployment project Virtualization infrastructure monitoring: Eating your veggies

You should also plan your backup strategy around your current or future disaster recovery strategy, since good backups are the foundation for any business continuity plan. You should look for a backup strategy that supports your requirements for recovering from an event. In addition, you may look into some of the products that can replicate your VMs from your production environment to a DR environment. Test the restore ability so that when you try to restore data later on you don't encounter surprises.

In virtual environments, small changes can have large effects, and a seemingly innocent configuration tweak can cause huge problems for your hosts and VMs. It is critical to have a change management process in which changes are reviewed and documented before they are implemented. You may not notice the effects of a change right away; it could take days or weeks before a problem becomes apparent. Often, when a problem occurs with a system that was previously working, the first question is, "What changed?"' The ability to correlate a change that was made to the cause of the problem can help you quickly resolve it. Third-party applications can document changes in the configuration of your virtual environment and correlate them with events and performance data.

Eric Siebert, is a 25-year IT veteran who specializes in Windows and VMware system administration. He is a guru-status moderator on the VMware community VMTN forums and maintains VMware-land.com, a VI3 information site. He is also the author of the upcoming book VI3 Implementation and Administration, which is due out in June 2009 from Pearson Publishing. Siebert is also a regular on VMware's weekly VMTN Roundtable podcast.