fracai
04-09-2010, 10:10 PM
A heads up to anyone using a custom sparsebundle to limit their TimeMachine backups (as in these (http://www.macosxhints.com/article.php?story=20080519051720677) hints (http://www.macosxhints.com/article.php?story=20080420211034137)).
While this seemed to work prior to 10.6.3, this latest system update introduces a new behavior where sparsebundles are resized to equal the size of the volume on which they reside. During the first backups following my upgrade, my 250 and 500 GB disk images were each resized to around 4 TB, the thin provisioned size of my Drobo. Resizing these volumes back down to their original sizes was useless as they were sized up again during the next backup.
Check Console.app (system.log) for something like:
com.apple.backupd[###] Resizing backup disk image from 150.0 GB to 4095.6 GB
This has also been discussed on the Apple boards here (http://discussions.apple.com/thread.jspa?threadID=2382434&tstart=0) and here (http://discussions.apple.com/thread.jspa?threadID=2383738&start=0).
I've filled a bug with Apple rdar://7839823 (http://openradar.appspot.com/7839823), but it's already been marked "Behaves Correctly". Apparently, an Apple created sparsebundle could be moved to a larger drive where it should increase in size, but Mac OS X cannot currently detect this action so the "safe" operation is to always resize if possible.
It may be possible to use a standard disk image which cannot be resized, but this would defeat the magic of using a sparsebundle which only takes up as much space as it currently needs to, growing as necessary up to its set maximum.
I don't agree with this resolution and have filled a feature request (rdar://7843424 (http://openradar.appspot.com/7843424)) to introduce a sanctioned method of limiting backups. This would be a better solution anyway, as the custom sparsebundle always seemed a bit of a hack. I'll be very surprised if this isn't closed as being a duplicate request.
Apple seems to treat duplicate reports as votes though, so if you're affected by this, head on over and report it (bugreporter.apple.com).
Also, the following defaults command pops up frequently, but I haven't seen any first hand reports or evidence that it actually works, with or without the /Library/Preferences/ path.
defaults write /Library/Preferences/com.apple.TimeMachine MaxSize <size in MB? kB? b?>
While this seemed to work prior to 10.6.3, this latest system update introduces a new behavior where sparsebundles are resized to equal the size of the volume on which they reside. During the first backups following my upgrade, my 250 and 500 GB disk images were each resized to around 4 TB, the thin provisioned size of my Drobo. Resizing these volumes back down to their original sizes was useless as they were sized up again during the next backup.
Check Console.app (system.log) for something like:
com.apple.backupd[###] Resizing backup disk image from 150.0 GB to 4095.6 GB
This has also been discussed on the Apple boards here (http://discussions.apple.com/thread.jspa?threadID=2382434&tstart=0) and here (http://discussions.apple.com/thread.jspa?threadID=2383738&start=0).
I've filled a bug with Apple rdar://7839823 (http://openradar.appspot.com/7839823), but it's already been marked "Behaves Correctly". Apparently, an Apple created sparsebundle could be moved to a larger drive where it should increase in size, but Mac OS X cannot currently detect this action so the "safe" operation is to always resize if possible.
It may be possible to use a standard disk image which cannot be resized, but this would defeat the magic of using a sparsebundle which only takes up as much space as it currently needs to, growing as necessary up to its set maximum.
I don't agree with this resolution and have filled a feature request (rdar://7843424 (http://openradar.appspot.com/7843424)) to introduce a sanctioned method of limiting backups. This would be a better solution anyway, as the custom sparsebundle always seemed a bit of a hack. I'll be very surprised if this isn't closed as being a duplicate request.
Apple seems to treat duplicate reports as votes though, so if you're affected by this, head on over and report it (bugreporter.apple.com).
Also, the following defaults command pops up frequently, but I haven't seen any first hand reports or evidence that it actually works, with or without the /Library/Preferences/ path.
defaults write /Library/Preferences/com.apple.TimeMachine MaxSize <size in MB? kB? b?>