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Mountain Lion: Time Machine Backups Get Very Big!

This weekend I upgraded from Lion to Mountain Lion, and most things work fine. I use an USB hardrive for backups, it's the same volume I used under Lion. Mountain Lion was able to continue using it, so I did not lose the history of my documents. So far, so good.


But: From time to time backups get really big. One example: This morning the backup that finished at 10:30 was about 50 MB at size, which is ok. The next backup started at 11:15 (and is still in progress), and while backing up, the estimated size grows and grows. Currently it's about 26,55 GB estimated, with 24 GB already backed up. But I did not produce more than 26GB of new or changed files, I just visited some websites, read news in Reeder and read some emails with Mail.app.


I saw this behaviour several times since monday, which lead time machine to clean old backups (previously I had backups from March, now the oldest backup is from May). What causes time machine to think that there is so much data not backed up, and why doesn't time machine know the size of the backup before copying the files, as it did in Lion?


Any suggestions?


Marcus

Macbook Pro 15, Mac OS X (10.7.2), 4 GB RAM, 512MB Video RAM. 320 GB Harddrive

Posted on Aug 9, 2012 2:50 AM

Reply
56 replies

Nov 5, 2012 1:04 PM in response to willmtaylor

After deleting the files, when you turn TM on, you should not see a previous back up date. If you see a previous backup date it means the plist files were not deleted. In my case I deleted the files and then emptied the trash. If you see the previous back up date, you may want to try that. Also be sure to unmount the backup disk and turning off TM before deleting the files.

Dec 2, 2012 8:13 PM in response to dape_75

I had a sparseimage disk mounted while doing a backup. I think this problem might have something to do with this; it might not have backed up properly the last couple of times, maybe because this sparseimage disk wasn't included in the exclusions or something.


TM semed to work OK without this - it performed a large backup with a fixed total size properly estimated (no moving-target problem now!), and then after that it performed a small (appropriately tiny!) backup the second time I clicked.


P.S. Also, after I unmounted the sparseimage disk, I also disconnected and then reconnected the backup disk.


I don't know why, but I suspect this has something to do with it, though probably there are other causes for this problem.

Dec 11, 2012 6:24 AM in response to Ivo G.

I deleted my Timecapsule and did a full new backup. I followed the steps to delete the backup plist file. Everything worked fine for 2 days. Then again a 35GB backup again. This drives me nuts as it is not happening when i do parallel backups to an external HD via USB.



11.12.12 12:06:45,998 com.apple.backupd[18389]: Starting automatic backup

11.12.12 12:06:49,175 com.apple.backupd[18389]: Attempting to mount network destination URL: afp://David%20xxx;AUTH=SRP@David-xxx-Time-Capsule.local/Data

11.12.12 12:06:58,103 com.apple.backupd[18389]: Mounted network destination at mount point: /Volumes/Data using URL: afp://David%20xxx;AUTH=SRP@David-xxx-Time-Capsule.local/Data

11.12.12 12:07:47,031 com.apple.backupd[18389]: Disk image /Volumes/Data/David xxx MacBook Pro.sparsebundle mounted at: /Volumes/Time Machine Backups

11.12.12 12:07:47,035 com.apple.backupd[18389]: Backing up to: /Volumes/Time Machine Backups/Backups.backupdb

11.12.12 12:08:00,280 com.apple.backupd[18389]: Using file event preflight for Macintosh HD

11.12.12 12:08:01,690 com.apple.backupd[18389]: Will copy (60.6 MB) from Macintosh HD

11.12.12 12:08:01,696 com.apple.backupd[18389]: Found 135 files (60.6 MB) needing backup

11.12.12 12:08:01,705 com.apple.backupd[18389]: 2.22 GB required (including padding), 1.5 TB available

11.12.12 13:08:00,190 com.apple.backupd[18389]: Copied 19.21 GB of 19.21 GB, 277398 of 277398 items

11.12.12 14:08:00,755 com.apple.backupd[18389]: Copied 29.28 GB of 29.28 GB, 470803 of 470803 items

11.12.12 15:00:31,064 com.apple.backupd[18389]: Copied 715064 files (34 GB) from volume Macintosh HD.

11.12.12 15:00:32,071 com.apple.backupd[18389]: Using file event preflight for Macintosh HD

11.12.12 15:00:33,499 com.apple.backupd[18389]: Will copy (16 MB) from Macintosh HD

11.12.12 15:00:33,506 com.apple.backupd[18389]: Found 114 files (16 MB) needing backup

11.12.12 15:00:33,508 com.apple.backupd[18389]: 2.62 GB required (including padding), 1.47 TB available

11.12.12 15:01:18,452 com.apple.backupd[18389]: Copied 3231 files (16.2 MB) from volume Macintosh HD.

11.12.12 15:01:20,293 com.apple.backupd[18389]: Created new backup: 2012-12-11-150118

11.12.12 15:01:28,938 com.apple.backupd[18389]: Starting post-backup thinning

11.12.12 15:01:42,750 com.apple.backupd[18389]: Deleted /Volumes/Time Machine Backups/Backups.backupdb/David xxx MacBook Pro/2012-12-10-115649 (15.4 MB)

11.12.12 15:01:42,751 com.apple.backupd[18389]: Post-back up thinning complete: 1 expired backups removed

11.12.12 15:01:43,289 com.apple.backupd[18389]: Backup completed successfully.

11.12.12 15:01:46,292 com.apple.backupd[18389]: Waiting for Spotlight to finish indexing /Volumes/Time Machine Backups/Backups.backupdb

11.12.12 15:02:51,305 com.apple.backupd[18389]: Waiting for Spotlight to finish indexing /Volumes/Time Machine Backups/Backups.backupdb

11.12.12 15:04:14,035 com.apple.backupd[18389]: Ejected Time Machine disk image: /Volumes/Data/David xxx MacBook Pro.sparsebundle

11.12.12 15:04:14,461 com.apple.backupd[18389]: Ejected Time Machine network volume.

Feb 8, 2013 1:09 AM in response to Marcus Muench1

Well, my original problem is not the size of the backups itself, it's that many backups start with an estimated size of i.e. 6GB, and at the end of the backup process the resulting size of this backup session is about 80GB, although no application was started or running while the backup was in progress. I think TimeMachine should be able to make better size estimations than this. The miscalculation leads to another problem: Before the backup starts, TimeMachine is cleaning up the TimeMachine volume so there is enough space on it for the backup. But if the estimated size is 6GB, and there are 8GB free on the volume, TimeMachine cannot finish the backup and fails with "not enough disk space". I never had this problem with Snow Leopard or Lion, only with Mountain Lion.

Feb 9, 2013 8:10 AM in response to Marcus Muench1

It happened again today. A backup that started at 431 MB kept growing until I stopped it at 8 GB!


No idea of why it happens. No new apps, no system updates, I had not worked with any big files. Just when the backup was reaching the 400 MB the estimated backup size kept growing and growing.


Repeated the steps previously described (delete the plist file etc.) and now back to normal after a big backup (116 GB). All my previous backups are there. Who knows until when...


I hope Apple does something about it.

Feb 10, 2013 11:41 PM in response to Jose Rodriguez Alvira

Massive Time Machine backups have been really driving me crazy for a while. I've finally discovered the cause of my massive Time Machine backups. The culprit was TechTool Pro. The directory backup feature in it creates massive directory data files for every volume it is aware of including past Time Machine disks that I've used.


I was previously using a Snow Leopard MacPro with one of my four drive bays occupied by a 2Tb Time Machine disk. It was doing massive backups then too, but since I didn't suffer notable performance issues when it would backup, I wasn't aware something weird was going on.


Now that I'm on a Mountain Lion Laptop synching to a Time Capsule disk over WiFi, I'm much more aware that my backups were out of control. I was having no luck finding the cause for the past two months until just now.


I looked in /Library/Application Support/TechTool Protection and the directory size was 90Gb. It was generating directory backup files that were more than 4Gb in size several times a day. Ok, that would explain how my backups could get so massive with so little seeming to happen. In all, my TechTool Protection folder was over 90Gb in size.


I turned off the directory backup feature in Techtool and my Time Capsule backups have been pretty manageable since.

Feb 28, 2013 7:45 PM in response to hyperlinked

I stumbled upon this page while searching Google for a solution to the exact problem most of the users seem to have here; Time Machine back up size are increasing (or not changing) even if there is no change in the system.


I couldn't find the proper answer here, so I looked elsewhere and found a very useful program Time Tracker via http://www.charlessoft.com/


Basically it shows you all the backups in a list form and the files that were backed up. So its essentialy the delta. Allow your backup to be complete (even if you think the size is large) and then check Time Tracker to see which files were backed up.


This will give you a clue as to whether you had modified the file or not.


In my case the issue was caused due to an encrypted disk image file I keep with all my important files. I load it everytime I am infront of my mac and then unload it before leaving :-). So what was happening was that each time the disk image loads and I make a small modification to one of the file in there and eject it, for TM the dmg changed. Thus it tries to back up the 32GB of dmg everytime I touched any file in it. I have excluded the file and for the last 5 times my back ups are of normal size (less than 1GB, which is what I expects as well).


Hope Time Tracker will give you all what your root cause as well.


PS: It is an independent download, so please use it at your own risk. I do not take responsibility if something goes wrong. It worked for me and that's all I can say about it.

Mountain Lion: Time Machine Backups Get Very Big!

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