An organization recently contacted me regarding its virtual desktop infrastructure deployment because the consulting firm it had hired to design and implement a virtual desktop environment had failed to develop a VDI backup strategy.
Every commercial virtual desktop infrastructure (VDI) product works differently, and backup requirements vary considerably, so there isn't one easy answer on what needs to be backed up. That said, you should concentrate on two areas when it comes to VDI backup: the virtual desktops and the infrastructure.
The virtual desktops
You might assume that you need to back up individual virtual desktops, but you don’t have to. That's one reason why companies adopt VDI in the first place -- simpler management.
Most organizations start out by setting up a physical PC with the operating system and applications they need to run on virtual desktops. Once the PC has been completely configured, it is Sysprepped, and then a golden image is created from the PC's hard drive. This gold image is used to create a virtual hard disk file, which serves as the basis for individual virtual desktops.
Once an IT shop has a copy of the virtual hard drive file that was used to create the virtual desktops, it doesn't need to back up each virtual desktop separately. As long as this file is stored in a safe place, a traditional backup of virtual desktops isn't necessary.
Of course, this raises a big question. As we all know, desktop PCs (physical or virtual) do not retain a static configuration. Things like patch management, new applications and user profile data can cause the desktop to evolve over time. So, how do you deal with this evolution if you are not backing up the virtual desktops?
As with physical desktops, the patch management process does not warrant backing up virtual desktops. If a problem occurs, the virtual desktops are recreated from the gold image, and any necessary patches are automatically applied by the patch management server.
New application deployment doesn't warrant backing up individual virtual desktops, either, because new apps are almost never installed directly to the desktops. Instead, administrators create a new gold image containing the new application and any authorized patches that have been released since the time that the last gold image was created, and the new gold image is used to regenerate the virtual desktops.
So, what about user profile data? Generally in a VDI deployment, the user's profile is redirected to a network share, which prevents any user profile data from being stored locally. In some instances, though, user customization can become a problem.
For example, Microsoft's Windows Server 2008 R2 VDI implementation allows for the creation of personal virtual desktops. Normally, when a user establishes a VDI session, he is connected to one of the virtual desktops within a desktop pool. At the end of the user's session, any changes that he has made to the desktop are rolled back so that the virtual desktop is left in a pristine state. However, with personalized virtual desktops, each user is mapped to a specific virtual desktop. When the user's session is finished, Windows skips the rollback process so that the next time the user logs on, he will be connected to the same virtual desktop that's in the same state in which he left it.
Anytime personalization technology is used, it's a good idea to back up virtual desktops. That way, you won't lose any user specific settings in the event of a crash.
The virtual desktop infrastructure
Because every vendor takes a different approach to VDI, it is difficult to say exactly what you need to back up. I recommend treating your VDI deployment as mission-critical and designing your backups so that you'll be able to restore service quickly in the event of a failure.
This doesn't necessarily mean that you have to back up every infrastructure server in your entire organization. After all, VDI deployments are almost always constructed with fault tolerance in mind.
You may be able to design your backups to achieve a representative sampling rather than back up every single server. For example, if you have an entire pool of session host servers, then it probably isn't necessary to back up every session host because they all do the same thing. Instead, make sure that you back up at least one session host as well as any configuration settings or databases used by the pool.
Since there is no "one size fits all" solution to backing up your VDI deployment, you must create a backup plan that is based on your own individual virtual desktop architecture and on the requirements set by your VDI software vendor.
ABOUT THE AUTHOR:
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server and IIS. He has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. As a freelance technical writer, he has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies.
This was first published in February 2011