11 Replies Latest reply: Oct 16, 2008 10:15 AM by Patricia W
Patricia W Level 3 (685 points)
I posted this to the wrong forum and am reposting it here ...

I just discovered that Time Machine has not been working for over a month (I looked at the backup drive and that was the date on the most recent folder.) So I looked at my Time Machine preferences and Time Machine was OFF. I'm pretty sure I didn't do that. I wonder whether it could be caused by my external drive being offline when Time Machine attempted to backup. I've had that sort of problem with other software. Instead of waiting until the drive comes online it turns the option off permanently. If that is the case with Time Machine it is pretty scary. It means that I can't rely on Time Machine. Has anyone else had this experience?
(The very least it could do is send me some sort of alert.)

iMac, Mac OS X (10.5.1), 2.4 GHz Intel Core 2 Duo
  • Mr.Lobotomy Level 4 (1,290 points)
    If your external drive is off, unmounted or disconnected when Time Machine wants to back up, Time Machine simply waits until the drive is mounted to perform its next backup task. This allows laptop users to leave the external hard drive at home while travelling. I have not seen Time Machine turn itself off.
  • Peggy Lynn Level 4 (2,470 points)
    Time Machine has never turned itself off if I eject its drive and turn it off. If this happens again you should report as a bug to Feedback.
    http://www.apple.com/macosx/feedback/
  • Patricia W Level 3 (685 points)
    Unfortunately whatever caused it to be turned off happened over a month ago. I've locked the preferences although from what I can see it is not possible to lock an individual preference so I have to remember to re-lock my preferences if I have to change any of them.
  • Peggy Lynn Level 4 (2,470 points)
    If any of your preferences change on their own this should be reported to Apple. There is a padlock in the lower left corner of of the window in System Preferences > Time Machine.
  • Patricia W Level 3 (685 points)
    As I think I said I have locked the preference but given that there is only one lock for all the preferences it makes it easy to unlock and forget to relock. As I mentioned, I don't know what caused the preference to change. I didn't notice it until it was too late.
  • Peggy Lynn Level 4 (2,470 points)
    I don't see any lock in System Preferences [Show All] but I do have one for Time Machine. Where do you see the lock for all System Preferences?
  • Patricia W Level 3 (685 points)
    There are a number of preferences that have padlocks (e.g. Sharing) but if you change one then they are all unlocked so I surmise that there is only one lock.
  • Peggy Lynn Level 4 (2,470 points)
    Mine work the same way. I never lock anything in system preferences so I've never noticed before. It would probably be a good idea to leave them unlocked for awhile and keep a sharp eye out to see if Time Machine decides to turn itself off again. It certainly shouldn't be doing any such thing under any circumstances and should be reported as a bug if it does.
  • nerowolfe Level 6 (13,065 points)
    It is remote, but some system log might indicate what happened.
    Check all your logs around the last date that TM did a backup and see if anything shows up.
    If it was a system glitch, it may be there.
    Just thinking out loud, but that is why there are logs.
  • Patricia W Level 3 (685 points)
    I went back in my system logs and around the time of the last Time Machine backup I see the following messages:

    Security policy loaded: Safety net for Time Machine (TMSafetyNet)

    But that message is showing up now so it probably isn't significant.

    Unfortunately I can't find any logs before Dec 2 (which is the date in question.)
  • Patricia W Level 3 (685 points)
    No longer relevant