External HD and Time Machine?

Discussion in 'Mac Basics and Help' started by deja-vu, Nov 25, 2012.

  1. deja-vu macrumors newbie

    Oct 16, 2012
    Hi guys,

    I have an MBP and would like to back it up using Time Machine. I have an idea about connecting a external harddrive (something like this: http://support.wdc.com/product/download.asp?groupid=208&lang=en) when i come home in the evening.

    So my question is: Will Time Machine start backing up immediately (more or less) when i connect an external harddrive via usb if i have set it up as a Time Machine drive first?

    Hope you can answer my question.

    Thanks in advance,
  2. bluespaceoddity, Nov 25, 2012
    Last edited: Nov 25, 2012

    bluespaceoddity macrumors regular

    Jun 14, 2009

    When you format the external drive with DiskUtility, then set it up for TimeMachine and keep TimeMachine enabled when you disconnect the drive (or disable right before disconnecting and re-enable right after re-connecting) TimeMachine will resume its incremental backup schedule soon after you reconnect the computer to the drive.

    Be aware that TimeMachine may take something called local snapshots during the time the computer isn't hooked up to its regular back up drive if you leave TimeMachine enabled.

    (After thought, may be redundant but added just in case. Don't forget to Eject the drive before unplugging it.)
  3. deja-vu thread starter macrumors newbie

    Oct 16, 2012
    Thanks for the fast reply. It sounds like this is the way im gonna go :)

    What happens btw if i forget to eject the drive? If I know myself I might forget this once in a while :-/
  4. BRyken macrumors 6502

    Jul 17, 2008
    I've forgotten to eject the drive many times and haven't had any problems, however it isn't recommended.
  5. I5acc macrumors newbie

    Nov 21, 2012
    I use 1TB external HDD for time machine and works fine....and about reject the disk....better if u do it because u never know what u can lose from drive:)
  6. bluespaceoddity macrumors regular

    Jun 14, 2009
    There is always a risk of data corruption when you unplug a drive without ejecting - resulting from improperly disconnected caches and other interrupted data transfers with the drive or unexpected disconnects from the controller on the external housing... By ejecting first you properly tell those processes to stop and thereby reduce that risk of data corruption. Try not to forget to do it. :)
    This may save you from a confrontation with corrupt backups or an unmountable drive when you need that drive the most - i.e. when you want to restore something from backup. Which is the very reason why you set this drive up with Time Machine in the first place.
    (The truly cautious will suggest a second independent backup system alongside these TimeMachine backups - to save you from multiple, simultaneous drive failures ...)

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