Why does Time Machine back up more data than changed on my HD?

Discussion in 'macOS' started by ks-man, May 29, 2009.

  1. ks-man macrumors 6502a

    Sep 25, 2007
    I have a new iMac that backs up regularly with Time Machine. I find that the Time Machine backups are for more data than my iMac hard drive changes. For example, yesterday it did three backups that I noticed. One was for about 300MB and the other for about 700MB and one for 2 MB. Right now it is doing a 1GB backup. The only changes I did to the iMac between yesterday and today were a few e-mail downloads (not more than 2MB) and a few pictures were imported (about 30MB).

    Does anybody know why Time Machine is backing up so much data when nothing is changing on my Mac? My entire hard drive is about 62GB right now and it started at about 58GB. My Time Capsule hard drive that hosts the TM backups has used about 130GB of data. It had only used about 60GB of data after the initial backup about a month ago.

    Any thoughts would be appreciated. Thanks.
  2. jimishjoban macrumors member

    Mar 24, 2008
    Time machine backs up meta-data about what has changed between two consecutive backups and also backups new files that were added after previous backup.

    So even if your HD is 60GB, the time capsule HD could be 130GB as it stores "extra" information that could help you retrieve a particular HD instance.

    You can try reducing number of times it backup every month...
  3. ks-man thread starter macrumors 6502a

    Sep 25, 2007
    Since I posted this message I imported some more photographs (the folder created in my iPhoto library for today is 175MB). The Time Machine backup where that was the only thing changed for my computer was 500MB. Does it really make sense that Time Machine would need a 500MB backup to do 175MB of data?
  4. miles01110 macrumors Core


    Jul 24, 2006
    The Ivory Tower (I'm not coming down)
    As jimishjoban said, TM backs up more than just the front-end files you're importing. 500 MB backup for 175 MB of files isn't totally unexpected.
  5. ks-man thread starter macrumors 6502a

    Sep 25, 2007
    Is there a way to change it so TM only backs up every other hour or every 6 hours? 4 times a day should be fine for me.

  6. crees! macrumors 68000


    Jun 14, 2003
    Just turn Time Machine OFF and when you want to perform a backup, either in the Dock or the status bar icon for Time Machine choose Back Up Now. This way you're doing manual backups as opposed to automatic ones.
  7. Phil A. Moderator

    Phil A.

    Staff Member

    Apr 2, 2006
    Shropshire, UK
    Are you using Entourage for email? If you are, then that's probably your problem: Entourage stores all the e-mail in a single file so every time you get an e-mail it backs up the entire mail store...
  8. srl7741 macrumors 68020


    Jan 19, 2008
    In my world

    If you think Time Machine backs up too often (or not often enough) navigate into /System » Library » LaunchDaemons. There you'll find a file named com.apple.backupd-auto.plist. Open it in your favorite text editor, and look for this section:


    Change the 3600 number to some other time interval in seconds, and you'll have changed Time Machine's backup interval.

    FYI Trick I found.
  9. Cerebrus' Maw macrumors 6502

    Mar 9, 2008
    Brisbane, Australia
    If you use VM ware, this can also contribute to very large incremental backups. You can add it to the Do Not Backup List.
  10. ks-man thread starter macrumors 6502a

    Sep 25, 2007
    I am using VMWare Fusion but I'm pretty sure my Windows Hard Drive (created from a Boot Camp partition) is already excluded from the list. Is there something else VMWare related that I should exclude?
  11. Cerebrus' Maw macrumors 6502

    Mar 9, 2008
    Brisbane, Australia
    As such, that should be ok, but I believe there is also a VMWare folder kept somewhere on your Mac drive. (If my memory doesn't fail me, I think in ~/Library, but not too sure) IF you do find it, try adding that to the list also, just in case it's linking past your exclusions list.

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