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Rzn8tor
Enthusiast
Enthusiast

Time Machine and Fusion

Perhaps someone who is beta-test Leopard can shed some light on this.

The backup software I'm using right now sees the Fusion virtual disks (vmdk's) as simple files, so any change (including just running the VM) triggers a backup of the entire file. It takes quite a while to back up a 60+GB file, even using firewire, so is there any way for Time Machine to do incremental backups of these files, or at the least to exclude them entirely?

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Wes_W_
Enthusiast
Enthusiast

Although I don't know anything about Apple's Time Machine implementation, there are a few other things you can try.

1) Consider using a command line program such as 'rsync' or 'cp' for your backups. Most of the GUI backup applications I've seen show files for backup as most users see them in OS X's GUI...but remember, OS X is UNIX. Excellent! Use a more traditional UNIX tool for the most control. For what it's worth, I do my backups with a small script utilizing simple piped 'cp' commands. The addition of Automator can ease this process as well.

Try: http://www.apple.com/macosx/features/automator/ or http://automator.us or http://automatorworld.com/index.php?s=backup&submit.x=0&submit.y=0 for more information.

2) If/when Apple implements the ZFS filesystem in Leopard (and I REALLY hope they do), you can use ZFS snapshots to keep incremental snapshots in real time if you place your Fusion VM's on a drive formatted with ZFS.

HTH.

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skapplin
Contributor
Contributor

FWIW: No Leopard beta tester can tell you anything about Leopard without violating the Non-Disclosure Agreement.

I doubt any Mac backup utility will be able to 'read' the content of a virtual disk. They will all simply see a change to the virtual disk and backup the entire file. Of course many backup utilities can be set to ignore certain files. You can then use Windows backup to backup your virtual disk the way your prefer but separately from your general Mac backup.

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Rzn8tor
Enthusiast
Enthusiast

From the Macworld Preview:

How will Time Machine work for people who modify gigantic files on a regular basis? For example, consider a 1GB database file. If I make a tiny modification to that file, Time Machine writes out another 1GB file to record that change. As a result, drive space on my backup device could quickly disappear. Apple suggests that the answer will be for application developers to modify their programs to break up data into more discrete elements that can be backed up more simply by Time Machine[/b]—something they may already be doing in order to make their files searchable via Spotlight. But will this pitfall drastically reduce Time Machine’s usefulness for some users?[/i]

Is something like this possible for Fusion?

From the Apple site:

By default, Time Machine backs up your entire system. But you can also select items you’d rather not back up.[/i]

So it appears that a strategy to back up VM's manually to a separate volume is feasible. It may be prudent to keep the guests' data files in a shared folder that is backed up by Time Machine.

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nathanp
VMware Employee
VMware Employee

From the Macworld Preview:

How will Time Machine work for people who modify

gigantic files on a regular basis? For example,

consider a 1GB database file. If I make a tiny

modification to that file, Time Machine writes out

another 1GB file to record that change. As a result,

drive space on my backup device could quickly

disappear. Apple suggests that the answer will be

for application developers to modify their programs

to break up data into more discrete elements that can

be backed up more simply by Time

Machine[/b]—something they may already be doing in

order to make their files searchable via Spotlight.

But will this pitfall drastically reduce Time

Machine’s usefulness for some users?[/i]

Is something like this possible for Fusion?

From the Apple site:

By default, Time Machine backs up your entire

system. But you can also select items you’d rather

not back up.[/i]

So it appears that a strategy to back up VM's

manually to a separate volume is feasible. It may be

prudent to keep the guests' data files in a shared

folder that is backed up by Time Machine.

I don't know if it helps for VMs because I've never tried it. If you have a 60 GB vm, you can split it into 31 (or so) vmdk files that are 2gb each.

/Library/Application\ Support\VMware\ Fusion/vmware-vdiskmanager

Or you can select advanced options when you create the VM and select the "Split disk into 2GB files" checkbox.

If the Time Machine really checks the file for differences rather than just looking at the time stamp then it may work, otherwise it will only back it up everytime you open it.

Another thing that you could do is get to a state you are happy and then make a snapshot of it. After that, a backup utility should only back up the snapshot differences (which hopefully doesn't grow to 60 GB).

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Rzn8tor
Enthusiast
Enthusiast

Another thing that you could do is get to a state you

are happy and then make a snapshot of it. After that,

a backup utility should only back up the snapshot

differences (which hopefully doesn't grow to 60 GB).

Good point. Surprisingly (to me), my redo-log file is almost half the size of my base vmdk file: 18.93 GB vs 40.91 GB. I'm curious as to what made so many changes, so I'll have to replace the snapshot and observe what happens.

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jack_e_lawrence
Contributor
Contributor

You can 'exclude' any drive, folder and/or file in the TimeMachine backup.

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