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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 15, 2013 8:29 PM in response to mrkgoo

Hi - I've been battling with this all day and think I may have found the cause:


I think Spotlight may be trying to index the back up drive as Time Machine is running - creating a vicious circle of the index constantly updating and Time Machine trying to back up the growing index....


I don't know if it is a coincidence but today I tried backing up with Time Machine for the first time since updating to 10.8.5 and experienced the "total backup size begins to increase once it gets to about 90% complete problem".


A 1.5GB back up swelled to over 10 times the size before I cancelled it, with subsequent attempts allowed to run until the drive was full and it errored out. I should note my back up drive was running low on space, but should still have easily been adequate for today's backup.


I tried all the suggestions I could find (manually deleting the "in progress" file from the time machine backup folder, deleting the Time Machine preference file, repairing permissions and verifying the disks etc.) without success.


Anyway, with Time Machine switched off but the backup drive still attached and mounted on my desktop, it spun up and there was constant disk activity for several minutes. On a hunch I wondered if Spotlight was indexing my back up drive...


I added the back up drive to the privacy/items to exclude section of Spotlight prefs and tried running Time Machine again.


Straight away I knew something had changed - the back up was going painfully slow (in KB increments) but I let it run and it sped up and the progress bar reached 100%!!!! Followed up by 5 mins of "cleaning up".


Having run several subsequent successful back ups - it appears to be fixed!


To sum up - check if your back up drive is listed under Spotlight's privacy tab in System Preferences. If it isn't in the list then add it. A dialogue box will pop up saying that Spotlight will still index the drive, which is a bit confusing, but this did the trick for me - hopefully it will work for others too...


Rob.

Dec 14, 2013 5:01 PM in response to robarmo

Rob, that sounds like a different issue than we were discussing.


We were talking about system folders being excluded from the backup for some reason, then re-included later, causing a massive backup size.


OF cours,e it could be related to indexing as well, but it doesn't sound exactly like your issue. For the record though, I've seen a similar issue that you were expriencing (slow incremental backups that take a long time). They usually resolved with some time.

Dec 21, 2013 12:29 AM in response to mrkgoo

Rob...

I am having the exact same problems... I am trying to back up my new rMBP to a new EHD... at 90% or so, the total backup size starts to climb.... After an extra hour I stopped it. I did that twice.


Currently I am running a new backup trial after deleting the plist.

So I will see what happens and then try your idea.


Were you using a Time capsule or EHD?


Thanks.

Dec 21, 2013 12:44 AM in response to Tigervision

I deleted the plist as Pondini A4.

I have reformated my EHD (and mac os j).

At about 90%.... total backup size begins to climb....


I am trying Rob's method and added EHD to be used for backup to Spotlight privacy.


This is a brand new rMBP 13". I used migration assistant to transfer my old data from MBP 2009.


Any one have any suggestions??

Pondini????


Thanks.

Mountain Lion: Time Machine Backups Get Very Big!

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