Just realized something about time machine. Perhaps someone can corroborate

Discussion in 'macOS' started by mca7, Nov 12, 2007.

  1. mca7 macrumors member

    Joined:
    Oct 28, 2007
    #1
    Lets say I have 4gb of t.v. shows in my Movies folder. Time Machine backed up the files and knows that the files are there. Now say I want to move the 4gb of files to new folder called "TV" and Time Machine backs this up. It now has backed up the 4gb of files twice. Once in the Movies folder and once in the new TV folder (on the external drive). Now lets say I want to move them again into a new folder. Time Machine will back this up in their new places now. Keep in mind I'm simply moving the files around on my computer, not copying them to these new folders. So on my external hard drive there will be 12gb worth of the same tv shows that only add up to 4gb on my computer since I moved them three times. So every time I move a file to a different folder Time Machine will back up another copy of it. This to me is going to chew up my external hd drive faster then I thought. I have tons of big video files that I'm moving around and all along time machine will be adding on copy after copy of the same file, eating up space on my ex hd.

    I tested this and it seems to be correct. So in order to consciously save space on my external hd i'll have to have the foresight to create a folder and just keep the big files on there and not move them. Or only back up once a day, which kinda blows since I like having Time Machine running in the back round for peace of mind. This is kinda annoying. I have plenty of extra space for now, but when I finally do run out of it I'll know why and its not gonna feel good.

    Anyone else think of this? Am I wrong? Or have any ideas/input/comments?
     
  2. gr8tfly macrumors 603

    gr8tfly

    Joined:
    Oct 29, 2006
    Location:
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    #2
    Interesting. I just tried the same thing on 75MB file. Moved from Desktop to another folder, then back. Free space reduced by that amount (doing "Back Up Now" between each move).

    I would not have expected that behavior, since TM should know the file itself hasn't changed and also knows which directories' content has changed.

    Hopefully, it's just a dot-zero issue. I agree - it doesn't seem like the proper behavior.
     
  3. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #3
    Yes if you move files around they get backed up multiple times. I have told TM to exclude the Downloads folder and the Desktop folders. I move stuff there a lot.

    If you think your movie file case is bad what happens if you use VMware Fusion or Parallels and there is a multi gigabyte VM file? One trivial change inside the VM and the entire file is backed up, every hour. It can fill your TM drive fast unless you exclude VM files too.
     
  4. gr8tfly macrumors 603

    gr8tfly

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    #4
    At least, the file has actually changed. It makes sense in that case. (I have my virtual hard drive excluded from TM, too.)
     
  5. mca7 thread starter macrumors member

    Joined:
    Oct 28, 2007
    #5
    I don't use any of those programs, let alone know what they are. I do know what parallels is though. Sorry.
     
  6. DanB91 macrumors 6502

    Joined:
    Jun 12, 2007
    #6
    after 24 hours, all hourly backups are erased except for the last one, and i believe the last back up of the day will be used as that back up for that day. and after a week all daily backup are erased, using the last back up of the week for that week. weekly backups are kept forever. sounds kind of confusing but it keeps ur backup from filling full up. but the way this works u must keep something for a week in order for u to have backup of that file forever
     
  7. gr8tfly macrumors 603

    gr8tfly

    Joined:
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    Location:
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    #7
    That's probably true. I'll have to check that tomorrow.

    That also means if you move something twice, a week apart, it'll still keep a duplicate. Not quite as bad as the original scenario, though.
     

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