Getting Parallels Desktop to only back up changes with time machine

I recently started using macosx’s awesome built in time machine software to backup to my western digital mybook world and it was all working great – the initial backup took some time but after that the incremental backups meant fast backups even over wifi, great just what i needed!

That was until i booted up my windows 7 installation via parallels desktop 6; it booted up fine and i did 30mins or so .net development, suspended parallels and did some other small things. It was at this point i noticed time machine was trying to backup 30gig .. odd i thought but assumed it might be cos this was the first time i’d run parallels since switching on time machine. I left it to back it up and eventually it did; the next day i did the same thing … and once again noticed parallels was backing up 30 odd gig .. eeeer crap! was my immediate thought; i don’t wanna add 30gig to my backups everytime i run parallels! some quick googling identified the problem, basically the .hdd drive parallels used is modified everytime you do something in windows (obviously). Some more googling led me to find numerous people had the same issue as me. Now to solving it!

The most suggested “solution” for this issue seemed to be to make time machine ignore the virtual machine hard drive altogether either through the option in parallels preferences or through time machine itself then backup the .hdd files manually. This simply would not do! the whole point of me switching to time machine was so i wouldn’t have to concern myself with manual backups; i’m too forgetful and/or lazy for that. Now i admit, due to the fact i access most stuff while in parallels from a mapped drive that is my macosx home directory my actual work woud be getting backed up anyway, but my windows install wouldn’t be & given how long it takes me to get my dev environment exactly how i want it; i don’t fancy having to do that if i need to restore! so another solution was needed …

Luckily the latest version of parallels includes some updated time machine integration; reading the internet it seems most people have struggled to make it work properly and the documentations within parallels and on their website is sadly lacking; also there is another factor which makes it een more confusing to know if you’ve got it working which we’ll discuss later.

Right onwards with the solution! boot up your virtual machine as usual, then from the apple menu bar go Virtual Machine -> Configure, from the resulting dialog select “Optimization”; you should end up on a screen that looks like the one below.

Untick the box that is highlighted by the red annotation if it is ticked, it seems time machine doesn’t like this setting. Now select the Backup option from the left, you’ll be presented with a screen like the one below.

Now this is the important part, change the “SmartGuard” setting to “Optimize for Time Machine”, this will make parallels work in snapshot mode, these just record the changes between snapshots and snapshots occur automatically. Press “Ok”. You can make a snapshot at anytime from the virtual machine menu in addition to the auto ones, i recommend you do one if it doesn’t auto do one right away.

Thats it pretty much; the confusing part is that for me the first time machine backed up after changing these settings it still backed up ALOT i guess this was cos the first snapshot was everything on the drive currently. After that it all worked great, just backs up a few changes if i’ve been using parallels.

Hope this helps!


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