Windows Tip Sheet
Ride the Virtual Time Machine
Explore and exploit a bevy of great new features in VMware Workstation 5.0 to roll back OS changes and even create virtual machines off different system "snapshots."
If you’re not familiar with virtual computing (products like VMware Workstation
or Microsoft Virtual PC), it’s time to crawl out from beneath that rock
you’ve been hiding under. In particular, you should be giving a good hard
look at VMware Workstation 5.0. VMware and Virtual PC (which became a Microsoft
product last year) have always leapfrogged one another in features; VMware’s
new version, however, is a pretty big leap forward.
Of special interest to busy Windows admins is the new progressive snapshot
feature. Basically, you can take a “snapshot” of your virtual machine
at any time, and then revert back to that snapshot whenever you like. It’s
kind of like System Restore, only it’s a complete, point-in-time snapshot
of the entire OS. So you can install Windows, take a snapshot, do all kinds
of testing, and then roll back to that pristine state at any time you like.
What’s better, though, is the ability to build new virtual machines off
of those snapshots (a capability Virtual PC offers, in a less-intuitive fashion,
through differencing drives). Here’s how it works: You get your virtual
machine to whatever point you like (say, Windows installed and fully up-to-date
on patches). You shut the virtual machine down and take a snapshot. That snapshot
can then form the basis for any number of other virtual machines, each of which
exists independently from the others. Need to test a new app? Just create a
new virtual machine based on your freshly installed Windows snapshot. You’ll
save all the time of installing Windows and get that same, fresh state to work
with. Of course, once virtual machines start using a snapshot as a basis, you
can’t modify that snapshot. You couldn’t, for example, open up the
snapshot and apply a service pack; doing so would invalidate any virtual machine
that was based on the snapshot. But this ability does save space: I can have
a dozen “freshly installed” Windows XP virtual machines that only
take up the space of one, because they’re all using a single, underlying
VMware Workstation 5 also has memory-sharing, which essentially means that
two WinXP virtual machines, each allocated with 256MB of memory, won’t
necessarily use 512MB of real RAM; they can share memory to a degree.
Virtual computing has always been valuable for testing and evaluating software,
and features like these snapshots and memory sharing make the virtual computing
software even more useful and convenient.
Don Jones is a multiple-year recipient of Microsoft’s MVP Award, and is an Author/Evangelist for video training company Pluralsight. Don is also a co-founder and President of PowerShell.org, a community dedicated to Microsoft’s Windows PowerShell technology. Don has more than two decades of experience in the IT industry, and specializes in the Microsoft business technology platform. He’s the author of more than 50 technology books, an accomplished IT journalist, and a sought-after speaker and instructor at conferences worldwide. Reach Don on Twitter at @concentratedDon, or on Facebook at Facebook.com/ConcentratedDon.