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Find What's Being Excluded from Backups and Remove Backup Exclusion Metadata Apps
Time Machine uses a specific metadata attribute to know which files and folders not to back up. We had a hint to that effect back in 2005.

It turns out that CrashPlan, the cloud backup service, uses the same metadata to determine what to back up. Macworld's Lex Friedman pointed me to a CrashPlan support article that looks at this, and that shows how to remove the exclusion metadata. To do so, you run the following command in Terminal:
 xattr -d com.apple.metadata:com_apple_backup_excludeItem <filename>
The CrashPlan article mentions this in particular to be able to back up VMWare virtual machines, which, oddly, have this attribute set.

After setting the attribute, you can run this command to make sure it's stuck:
sudo mdfind "com_apple_backup_excludeItem = 'com.apple.backupd'"
You'll find a list of files that Mac OS X excludes by default.
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Find What's Being Excluded from Backups and Remove Backup Exclusion Metadata
Authored by: dilvish1984 on Jul 16, '12 09:04:40AM

You should probably mention somewhere in the body of this hint that the list generated by the second terminal command is not complete. The 2005 hint you mention in your first paragraph explains, largely in the comments (especially this one, this one, and this one) that there are at least a couple of other mechanisms used by Time Machine to determine which files and folders will not get backed up.

Also, your last paragraph seems to indicate that the list returned by mdfind will include items that the user has manually excluded using the Time Machine "Options..." panel (in its system preference pane), but this doesn't appear to be the case (and is directly contradicted by the 2005 hint, by the way).



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Find What's Being Excluded from Backups and Remove Backup Exclusion Metadata
Authored by: kirkmc on Jul 16, '12 09:56:23AM

I've corrected that, thanks.

---
Mac OS X Hints editor - Macworld senior contributor
http://www.mcelhearn.com



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Why virtual machine images are excluded from Time Machine backups by default
Authored by: richard2 on Jul 16, '12 09:36:52AM

Parallels and VMware exclude their virtual machine images from Time Machine backups by default to prevent Time Machine from backing up gibibytes of duplicate data every time an image is changed in the slightest. This is arguably a deficiency in Time Machine, which is compounded by the archaic single-file image format used by Parallels and VMware.

I'd recommend that people who use virtual machines keep their images excluded from Time Machine backups, and backup their images separately using rsync-based backup software.



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Why virtual machine images are excluded from Time Machine backups by default
Authored by: Westside guy on Jul 16, '12 11:54:50AM

Yeah, it wouldn't take long to fill up even a multi-terabyte drive if a person were including their virtual machines in their Time Machine backups.

I only keep one backup copy of my VMs. I don't even bother with rsync - I just, every so often, manually drag a VM over to the backup disk (which creates a copy, obviously). Some VMs are only testbeds, so those don't get backed up at all.



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Find What's Being Excluded from Backups and Remove Backup Exclusion Metadata
Authored by: Demani on Jul 18, '12 07:46:50AM

Yeah-VMWare and Parallels both have built-in backup routines that would allow you to back up your virtual machine to a separate file on a daily basis (or whatever you find useful). But the size of those files is way too large (my VMs typically are 15-20GB each), and they change just by starting them up. If it is a big deal to have those backed up, set up an external drive (decent USB flash drives are available) and use them as the location for the VM backups. You wouldn't want to run them directly off that, but you will still have decent backups you can pull with you.

Alternately, use a backup utility within windows to back it up-that too is an effective and efficient method, plus you have a multitude of tools to choose from.

But using Time Machine to backup VMs is highly inefficient.



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