Time Machine on a Laptop

Discussion in 'macOS' started by dvkid, Oct 31, 2007.

  1. dvkid macrumors regular

    Joined:
    Feb 18, 2006
    #1
    It is my understanding per the explanation of the guy at the Apple Store that when you disconnect your Time Machine drive your computer's hard drive is used to temporarily store backups until that drive is reconnected. The length of time you could go on with this being effective is directly related to the amount of free space you have on your internal drive.

    In my case, being that my MacBook Pro is not always at my desk, the time between backups could be up to 12 hours (excluding being on vacation).

    My plan is to take a bunch of the Apple Loops for Soundtrack Pro and video source files and particle systems for Final Cut Studio and dump them onto a 160 GB external bus powered drive (OWC Mercury On The Go from macsales.com). I also use that same external drive to capture video onto and store my render files.

    As my Time Machine drive I'll use a 750 GB Mercury drive connected via FireWire 800 each night. I would also like to find a way to backup my external 160 GB. Ideally it would work like Time Machine. But is Time Machine only capable of backing up what's on the primary OS drive?
     
  2. saltyzoo macrumors 65816

    saltyzoo

    Joined:
    Oct 4, 2007
    #2
    This is incorrect. While you are disconnected, time machine continues to keep track of all files that have changed. When you reconnect they are backed up, but you only get one backup per file, not multiple backups for files that may have changed multiple times while you were disconnected.
     
  3. LMO macrumors member

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    Jun 8, 2007
    #3
    Time Machine receives notifications from the OS whenever a file is created, changed, or deleted. It is my understanding that those notifications are saved until the next time Time Machine runs, either on it's regular schedule or when the Time Machine volume becomes available.
    Time Machine backs up everything, except for system caches and temp files, unless you tell it to exclude items. That includes external drives.
     
  4. cmaier macrumors G3

    Joined:
    Jul 25, 2007
    Location:
    California
    #4
    I believe it receives notifications only when it polls FSEvents for changes. So TM asks what directories have changed since the last time it asked, then it compares each directory to the last backup to see what files have changed, and backs up those files. (Just quibbling with the "whenever a file is created, changed, or deleted" language).

    Anyway, the result is the same: when you plug a drive in, TM can find out what files have changed since the last backup, and back those up. If you change a single file 10 times while unplugged from the external drive, TM doesn't keep track of the 10 changes. It only knows that the file is different, and you get a single backup when you plug back in.

    Also, while unplugged, no space is used (beyond the normal FSEvents log) for backups. Again, the files are not actually backed up while you are unplugged. All that happens is that a log file keeps track of the fact that a directory changed (not even that a file changed - it's done on the directory level).
     
  5. dvkid thread starter macrumors regular

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    Feb 18, 2006
    #5
    Ok, great. So I'll just plug in all the externals I need to backup each time I'm at my desk and all should be well. Might even put them on a FireWire hub so I only have to plug in one cable. Hmm...Finally a backup plan that is easy to maintain.
     
  6. Hard-Hat-Mac macrumors regular

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    May 18, 2007
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    Philly Burbs
    #6
    my mac HD turns into the Time Mchine drive after I disconnect my external drive. how do I make sure time machein backs up to the external after iconnect and not to my internal?
     
  7. dvkid thread starter macrumors regular

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    Feb 18, 2006
    #7
    What is giving you the impression its using your internal drive?
     
  8. Hard-Hat-Mac macrumors regular

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    May 18, 2007
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    #8
    it has the same icon as my time machine drive. if i boot up sometimes it goes back to the standard drive icon.
     
  9. cmaier macrumors G3

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    Jul 25, 2007
    Location:
    California
    #9
    What has the same icon as your time machine drive?
     
  10. vansouza macrumors 68000

    vansouza

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    Mar 28, 2006
    Location:
    West Plains, MO USA Earth
    #10
    Time machine backs up my main iMac drive and one other external I have connected to it. So it can back up more then the primary OS drive. :) :apple:
     
  11. Hard-Hat-Mac macrumors regular

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    Philly Burbs
    #11
    My internal HD "Macintosh HD" they both have the time machine drive icon.
     
  12. cmaier macrumors G3

    Joined:
    Jul 25, 2007
    Location:
    California
    #12
    Ok, I don't know what you are saying (does anyone else?), but I'm pretty sure you are misinterpreting things. Time machine isn't going to use your internal drive for backups.
     
  13. Hard-Hat-Mac macrumors regular

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    May 18, 2007
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    Philly Burbs
    #13
    my internal HD has this logo [​IMG]

    And so does my G-Drive which I enabled time machine on.
     
  14. coorspate macrumors regular

    coorspate

    Joined:
    May 20, 2006
    #14
    mine is doing the same thing. dont know why.
     
  15. cmaier macrumors G3

    Joined:
    Jul 25, 2007
    Location:
    California
    #15
    I think it means "this drive is backed up in time machine." (and when it appears on an external drive, "this drive is the target of time machine backups.")

    People aren't sure if it is a bug or if it is intentional. In any event, it is not copying files TO your internal disk, despite the icon.
     
  16. Guy Incognito macrumors regular

    Joined:
    Oct 15, 2006
    #16
    I think that this is actually a more general bug in the Leopard finder. For a while, the Finder displayed the Adobe Bridge icon for a partition on my external drive. After a reboot, it displays the correct icon.
     
  17. Hard-Hat-Mac macrumors regular

    Joined:
    May 18, 2007
    Location:
    Philly Burbs
    #17
    hmmm that would make sense. It's just not a normal sight is all. I like my old school metal HD drive icon.
     

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