Time Machine - Size of External HD needed/recommended

Discussion in 'Mac Apps and Mac App Store' started by ViperrepiV, Nov 17, 2008.

  1. ViperrepiV macrumors regular

    Jan 25, 2008
    Hello all,

    I recently bought a 3.06 Ghz iMac, and upgraded to the 750GB hard drive. I hvae a 500GB external hard drive lying around, and I would like to use that for Time Machine backups, if possible. My question is, do you think that is big enough? I would like to avoid buying an additional external 1TB drive for backups if I can avoid it....

    I plan on creating a 75GB partition for XP, which of course won't be backed up with Time Machine, so I am guessing that should leave, about 660GB of fee usable space (750 / 1.024 - 75 = 657.4). I have about 50 GB of music and 200GB of videos, and lets say the rest (OS + documents + pictures) will be about 50GB. So that is a total of 300GB from the get go, leaving me 200GB free of backup space on the external (although that assumes that TIme Machine doesn't compress, which I think it does)

    Anyyyyways, I doubt I'll fill up the internal HD fully, so given this info, do you think I will be okay with my existing 500GB external?

    I'm thinking it might be fine, maybe for like a year or so, since time machine just records the changes to the computer (i.e. data additions). Let's say it fills up by then. Can I just re-format the external and start the time machine backups from scratch? I figure I will use time machine mostly as protection against internal hard drive failure as opposed to a file recovery tool, so I doubt I'll care if I lose a year's worth of history, so long as I have a recent backup.

    Thanks for the help
  2. MasterNile macrumors 65816


    Apr 9, 2008
    San Antonio, TX
    If this is the case maybe you should consider using Carbon Copy Cloner (or SuperDuper but I don't have experience using that) to clone the hard drive and then use incremental back ups, that way if the internal hard drive does fail your back up is bootable. Either way it sounds like your current external will work just fine, at least no reason to run out and get a new one until you've got more than 500GB of data to fill up the external.

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