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Calby

macrumors 6502
Original poster
Dec 30, 2015
332
40
Sweden, Gävle
Hi,
I have Parallels 12 and I'm wondering if I back it up trough my Time Machine does it backup the whole file every backup? The file is like 15GB so I don't want it to back it up every time only when it's changes or only the files that are changed.
 
I don't believe Time Machine does block level differential backups so if the Parallels virtual disks are single files it will back up the entire file every time it changes. I use Fusion rather than parallels which works in the same way and for that reason, I exclude my VMs from Time Machine backups
 
I'm wondering if I back it up trough my Time Machine does it backup the whole file every backup?
TM will see the smallest change, and back up your entire VM, you will quickly fill up your TM volume. I'd exclude your VM folder from TM and then manually copy it to another external drive.
 
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One note - SmartGuard (that TM backup optimization mentioned in the previous post) makes use of VM snapshots. From my experience snapshots will slow down the VM performance - and depending on the usage scenario the performance drop may be pretty significant (if the workload running in the VM is IO intensive). So you trade the backup size and time for some performance. You pick what's more important for you...
 
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Don't do this with VirtualBox VMs either. The entire disk image is backed up by Time Machine, even if only one byte changes.

Like some others here, I exclude the VirtualBox folders from Time Machine and manually archive as necessary. Luckily, I don't rely on my VirtualBox VM instance for much; all of the key data is backed up outside of the VM disk image in manageable sizes (like less than 100MB).

I basically back up the VM disk image so I don't have to rebuild the system from scratch. I do this after substantial Windows updates so I don't have to download and install that stuff again.
 
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