Whether it’s Drive Vaccine, SmartShield, Deep Freeze, Time Freeze, or the old Steady State, there are pitfalls to using these tools and using them incorrectly or in the wrong situation will cause more harm than good. If you’re considering (or already are) using one of these programs, you should consider what your use case is and whether or not it’s really the right move.
Problem 1: Drive snapshotting causes performance degradation
Simply setting a snapshot (or baseline or whatever terminology the vendor decides on) and giving the computer to a user is a bad move. If you don’t set the computer to automatically restore to that snapshot everyday or sooner, the snapshot will just grow and grow and it won’t take long at all before the computer has to struggle to compute every block of commonly needed information against the original baseline. The more blocks need to be reconciled, the slower the computer will be. After a few weeks, the computer will be so sluggish and unresponsive, that your users will either start putting in tickets complaining about performance issues or they will just sit there and silently think less of you. These problems can also lead to other problems, like software installers stalling for no apparent reason.
It’s important to note that it doesn’t matter how recent the last snapshot is. The computations must be made against the baseline taken at the time that the software was initially installed. The only way to reset this situation is to completely uninstall and reinstall the software.
Problem 2: Drive snapshotting is a lousy backup strategy
The rapid recovery speed of a drive snapshotting technology may make you tempted to take a snapshot and leave it this way in case you need to restore to a working state at some point in the future. The performance issues mentioned in problem 1 make this a really crappy idea. Having a computer that’s slow all of the time is a poor tradeoff for being able to restore quickly. Just use drive imaging software (Clonezilla, Ghost, etc) or some other traditional backup strategy like a sane person. Sure, the recovery time is a little longer, but it has literally no impact on the daily operation of the computer. Of course, these backup strategies suffer from issues too, which leads us to the next and last point:
Problem 3: Snapshots become old and unreliable too
Reverting to a snapshot is like using an old\stale image to setup a computer. Say you take a snapshot and give the computer to a user. A year later it breaks and you go to restore to snapshot. Well, congratulations, you now have a broken domain trust relationship, old versions of browsers, plugins, etc, and are still missing all of the user’s newer data that was created\modified after the snapshot was taken. You now have an additional 30 minutes of work to get a computer to, what I consider to be, an unclean and unpredictable state.
When you use a modular imaging solution that stays up to date, like MDT, why not just simply put a new image on the computer and be done with it?
Essentially, the take away should be this: Only use drive snapshotting in situations where the computer will be automatically restoring to the snapshot frequently (daily or sooner). Don’t use snapshots as a longer term disaster recovery strategy. Either reimagine the computer like everything else or capture an image using cloning tools if the setup is really that precious.