Time Machine doesn't save hourly image on laptop when BUD not attached

Discussion in 'macOS' started by danpat, Oct 28, 2007.

  1. danpat macrumors newbie

    Joined:
    Apr 4, 2007
    #1
    TM doesn't appear to make a local hourly image when your TM drive isn't attached.
    There goes all the love from laptop owners!


    I have two laptops, a MBP and a PB G4. The MBP was TM'ed to a 500Gb USB2 drive on friday night and has been connected since. This was done with existing data on the drive and without reformatting or any other messing around.

    I decided to get TM going on the PB, so disconnected the 500Gb from the MBP and connected to the PB. Time machine opened straight away, asked to backup to the 500Gb and proceeded to create a backup of everything on the PB.
    Meanwhile I kept the MBP on and running, mainly just web browsing.

    TM finished with the PB and on looking at TM, there was a (very short) history of the drive since it was backed up. It had also added a second subfolder within 'Backups.backupdb" which was called "<username> Powerbook G4", alongside the already created "<username> MacBook Pro".

    When I connected the 500Gb back to the MBP, gave TM a few minutes to think, and checked TM's history there was nothing new between "Now" and when the TM drive was last connected.

    I hope this answers some questions.

    Please Apple, address this for laptop users and provide some option to save images to a local temp location until the TM drive is reconnected.
     
  2. Chef Medeski macrumors 6502a

    Chef Medeski

    Joined:
    Jun 14, 2005
    Location:
    New York, NY
    #2
    Yeah I think it was known for quite awhile that Time Machine only works when you are connected to an external HD. I like the temp location. But, you could not use Time Machine without the HD because it needs the original complete backup to restore all the files. Each archive after the initial is merely a slice to see what has changed. So if you put these files in a temp while your computer was disconnected. You could not use them until you connected to Time Machine. But still that would be sweet. I like the idea. The only other potential glitch is if Time Machine used the external to compare to the internal to look for differences. But I dont think it does. I've heard it merely uses an internal system tracker to tell when changes are occuring and thus when its time to update just backing up those changes.
     
  3. danpat thread starter macrumors newbie

    Joined:
    Apr 4, 2007
    #3
    You get it.
    Basically I would like the option (and i'm sure its not for everyone) to say "here's 5Gb on my internal drive to save version changes until I reconnect to my BUD". When I reconnect, these files get uploaded to the BUD, TM's history is refreshed with whats been happening while i've been away, and the 5Gb buffer is cleared. From what I understand, TM uses Spotlight's file referencing to recognize whats in a file and what changes have been made. I'm sure it would know when I change a local file without having to look at my TM BUD to know that something has changed.

    There may need to be some advanced selections here such as "yes/no delete older version when i save new changes", "yes/no only backup files under 10Mb", "save local images for 1 day/1 week/1 month" etc. Im sure it can't b too hard.
     
  4. pb30 macrumors newbie

    Joined:
    Jul 2, 2007
    #4
    http://www.apple.com/macosx/features/timemachine.html
     
  5. richard.mac macrumors 603

    richard.mac

    Joined:
    Feb 2, 2007
    Location:
    51.50024, -0.12662
    #5
    time machine uses a special daemon that points to all the files that have changed since the last backup and makes "hard-links". if the time machine external drive is attached it backs up those changed files every hour. if its not attached i.e. a notebook, it waits until one is attached and then backs up the changes. if you aren't downloading a lot of stuff and aren't doing a lot of video work the backups after the initial big backup are very small and quick. my last backup was 20MB and took about 20 sec on a firewire drive
     
  6. danpat thread starter macrumors newbie

    Joined:
    Apr 4, 2007
    #7
    Im going to have to do some more experimenting, because when I reconnected my BUD there was a 4 hour gap between windows/images/snapshots in TM from when it was last connected, to when it was reconnected.
     
  7. richard.mac macrumors 603

    richard.mac

    Joined:
    Feb 2, 2007
    Location:
    51.50024, -0.12662
    #8
    thats because is backing what happened in the last four hour interval snapshots! it doesnt backup 4 seperate times if you reconnect it after 4 hours, the daemon just adds more hard-links and they add up in the 4 hours. when ou reconnect it just backs up those changes.
     
  8. DanB91 macrumors 6502

    Joined:
    Jun 12, 2007
    #9
    this is not a bug, its just how TM works. if TM saved everytime the external hdd wasnt connected my hdd would already be full! that would be a serious design flaw.
     
  9. cmaier macrumors G3

    Joined:
    Jul 25, 2007
    Location:
    California
    #10
    Remember that the purpose of time machine is not version control; it's backup. If it was intended for version control, then rather than hourly backups, you'd want it to backup every time the file changed.
     
  10. nova-ex macrumors newbie

    Joined:
    Dec 10, 2007
    #11
    Ah seriously. Can we move on about TM and get ZFS already. I personally find TM very unsuited for my needs.
     

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