New iMac owner here, question about backing up via TM?

Discussion in 'iMac' started by pulawman, Jul 5, 2010.

  1. pulawman macrumors member

    Jun 12, 2010
    Indianapolis, IN

    Just picked up my 21.5 iMac this past Saturday. I've my 1tb ext drive up as my backup drive and for my itunes library all on one partition.

    While doing a little reading I've come across people stating that once time machine fills up, it will then start deleting older backups/files to write new ones.

    The way I understood, was that time machine would just keep overwriting the original backup fie, but I'm guessing I misunderstood that.

    So, is it safe to keep my TM backup and my iTunes media all in one partition, or should I partition a sector for TM? Would I be better off getting another ext drive for time machine specifically? If so, how large should I go?

  2. old-wiz macrumors G3

    Mar 26, 2008
    West Suburban Boston Ma
    I prefer the option of two partitions. There's a good reason for it; suppose you have a 400 gb HD in one partition, and you have 100 gb of your data backed up (not via time machine). Now there's 300 gb available for time machine and eventually time machine will fill up the space until it fills up and starts deleting. If at that point you want to put another 20 gb of your backup stuff (not TM), it will not fit since time machine has filled the drive.

    Ifyou split it into 200/200, then you only have to worry about filling your 200 backup stuff.

    hope this is clear, if not ask!
  3. sjinsjca macrumors 68020


    Oct 30, 2008
    Older versions of each file will be overwritten as space runs out.

    So if you have a word-processing document that you've been editing over a period of months, Time Machine will start overwriting its earliest revisions as space runs out.

    In the case of your music, the files don't change from day to day, so the original backup will remain untouched.

    Incidentally, it's always a good idea to have more than one backup disk. I have two 1TB Seagate USB drives which I use alternately. That way, if one fails right when I need it (and I've had that happen), I'm covered. Recommended.
  4. sjinsjca macrumors 68020


    Oct 30, 2008
    Apple recommends that your backup drive be at least twice as big as the drive being backed up to prevent this situation. It's good advice, and with external hard drives as cheap as they are, it's easy advice to heed.

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