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I back up my Lion via Time Machine as usual. Is it a good idea to exclude some huge files? For example, the VMWare virtual machine image is 15GB which consumes 1/8 of my SSD drive, I worry TM will use too much space and/or take too long keeping the large file backup'ed.

Should I leave it to TM, or backup the large files separately?

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Backup large file such as DMG(read/write) and Virtualbox image will get the TM disk full. So I exclude them from TimeMachine. But I backup them to another disk by script manually one week.

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If your VMware virtual image is 15GB in one file, every time you fire up the virtual machine, the image will change. Time Machine will have to make a new backup for it, which will ultimately result in ~15GB or more being backed up every time you run Time Machine. Every day, every hour.

Obviously, this is very time-consuming. Backups will be faster if you have an external FireWire 800 drive, but it still takes a considerable amount of time. And CPU – my system becomes very unresponsive when a large backup is made.

If you can afford to keep a separate backup of such a huge file that constantly changes, then by all means, do that, and exclude it from Time Machine. For example, you might not even want to maintain an hourly backup of your VM because it's not that important. In this case, it'd be easier to back up the file separately.

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VMWare Fusion, does not use a sparse disk image for it's virtual machine. (<B>That's surprising!!!</B>) But if you exclude your Virtual machine, just turn on VMWare's<B> Auto-protect.</B> The snapshot's the Fusion makes are Time Machine aware, and can be backed up reasonably... See – Benjamin Schollnick Mar 22 '12 at 18:22
Ah, that's good to know! – slhck Mar 22 '12 at 18:26

It depends on what you want. Do you need a backup or not. In my setup all VMs are for test purpose and left out.

Time machine is smart enought to check where the VM changed, because it's not only one large file but more like an .app-Folder. To be on the safe side you could also enable vmdk splitting into 2GB-files in VMware.

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I need backup of the vm after the first installation, and probably after installing of some important software. – ohho Feb 27 '12 at 10:07
then I would leave it in. – Mose Feb 27 '12 at 11:09

I have many virtual machine disk images on my computer. I exclude all of them from backups because they'll fill my Time Machine volume far too quickly with changes. But at the same time, I'm very careful to keep all my data for these virtual machines (code that I'm testing on these machines) outside the virtual machine itself (in folders shared from my Mac). That way, everything important is still backed up and content of the virtual machines themselves are irrelevant.

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