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sydeny2000 Author

Level 1

0 points

Time Machine intermittently backs up a large amount unnecessarily

SometimesTime Machine backs up 20 GB to 30 GB+ of data after initially finding a much smaller amount to back up.

Each time this happens, the back up goes something like this:

Time Machine starts and finds X MB to back up
The back up proceeds with status messages like "Backing Up: Y MB of X MB" until Y = 0.9 * X, i.e. 90% of X
Then the back up continues with X increasing and Y always 90% of X until it's backed up a large amount of data, usually well over 20 GB.
The back up finishes successfully and Time Machine cleans up.
I run more than one Time Machine back up volume (more on this below) with Time Machine cycling through them. I can see that the back ups immediately before and immediately after this one, both to the other back up volume, do not back up this large amount of data. This indicates that for those back ups, Time Machine does not think that files have changed.
When I check the large back up just made with TimeTracker, I can see that many, if not most, of the files backed up certainly would not have changed since the prior back up to this volume and, in fact, would not have changed since the last system update. It's backing up, for example, most of the files in /Applications

The multiple back up volumes I have, which Time Machine is configured to cycle through, are:

A Time Capsule permanently on the network
A FW800 external drive permanently attached to the MacBook
A FW800 external "mobile" drive I take on the road for back ups and which I periodically attach when not on the road.

MacBook Pro, OS X Mountain Lion (10.8.2)

Posted on Apr 11, 2013 10:50 PM

20 replies

sydeny2000 Author

Level 1

0 points

Jun 22, 2013 5:38 AM in response to Pondini

So look at the actual backups for the combination of what (TM thinks) changed and what was still on your Mac but didn't change.

I compared the /Applications in the 27 May 26.7GB backup with /Applications as it is now and it looks like it was a complete backup of all apps in the /Applications folder as it was then. I simply used ls -d * to get a list of the files in each and didn't do a full recursion.

The total size of the folder on the backup doesn't seem to be large enough to be a full backup, as it's only just larger than the current /Applications on the disk, and I've delete a few large third-party apps since the backup. So I suspect that not all files in every app were backed up. Could be wrong on that.

Now, my question is, what is it doing now? Does your most recent backup have the correct contents?

It's working fine now. Most recent backup has the correct contents, as have all backups since the erase and restore.

If it's any use to you, I'll still send the current /Library/Preferences/com.apple.TimeMachine.plist to you. Let me know if there is anything else you want.

One odd feature of the plist: there is a very large number of Parallels VMs in the IncludeByPath list. Many copies the .mem file from (it seems) every VM I've ever run. And that's despite the parent VM (the .pvm directory) being in the ExcludeByPath list for each VM. They are all turned off in Parallels, so that's what I'd expect.

None of those .mem files currently exist because the VM isn't running. Still, odd.

Pondini

Level 8

38,863 points

Jun 22, 2013 5:47 AM in response to sydeny2000

sydeny2000 wrote:

. . .

If it's any use to you, I'll still send the current /Library/Preferences/com.apple.TimeMachine.plist to you. Let me know if there is anything else you want.

Won't help much, but won't hurt, either.

One odd feature of the plist: there is a very large number of Parallels VMs in the IncludeByPath list. Many copies the .mem file from (it seems) every VM I've ever run. And that's despite the parent VM (the .pvm directory) being in the ExcludeByPath list for each VM. They are all turned off in Parallels, so that's what I'd expect.

That is pretty strange.

I don't really quite understand the whole IncludeByPath thing anyhow -- other than drives, everything else is exclusions. Seems odd to explicity include things, rather than just not exclude them.

Curiouser and curiouser!

Pondini

Level 8

38,863 points

Jun 23, 2013 5:20 AM in response to sydeny2000

Just saw your plist, and yes, it's the strangest one yet!

Both ExcludeByPath and IncludeByPath are full of odd things.

It doesn't mattter, bu the items in your Pictures library are not supposed to be listed there at all, but separately, via exended attributes, as "Sticky Exclusions."

I have no idea why all those old VMs are listed; have you tried replacing the plist, via a "full reset" of TM, per #A4 in Time Machine - Troubleshooting? That should get rid of the old ones, but I don't know if something will bring them back.

Thanks, and keep an eye on it . . .

sydeny2000 Author

Level 1

0 points

Jun 23, 2013 10:02 PM in response to Pondini

I've not done a full #A4 reset before.

Just did one and I'll watch it for trouble.

The new plist, after one backup, does not contain these items that were in the old one:

DestinationUUIDs
ExcludeByPath
FirmwareCheckDates
FirmwareCheckDatesLion
FirmwareCheckDestinationAlias
HostUUIDs
IncludeByPath
LastCompactTime (understandable 🙂)
LocalizedDiskImageVolumeName
PreferencesVersion
RootVolumeUUID
SkipPaths
TimeCapsuleName (first backup wasn't to the Time Capsule)

I expect some of these will return after more backups, e.g. the last when it backs up to the Time Capsule.

Pondini

Level 8

38,863 points

Jun 24, 2013 4:25 AM in response to sydeny2000

I'm not sure just running backups causes it. It seems connected to installing and/or running a 3rd-party app that wants to exclude something. We don't know whether it's any such app, or a particular one or ones.

Time Machine intermittently backs up a large amount unnecessarily