10 Replies Latest reply: Feb 16, 2008 4:34 PM by William Beem
Lincoln Nymeyer Level 2 (295 points)
I am new to Time Machine. In fact, I just installed my new ext. hard drive that I have dedicated for the time machine and it ran the first backup consuming about 40 GBs. I know that each subsequent backup will only reflect any changes since the most recent backup, so they will be much smaller, but I am wondering what happens when the external hard drive is eventually full?
Does Time Machine cycle on itself and begin recording over the oldest data? or does it just open a window telling me that the disc is full? If that is the case, what do I do when the disc is full? Do I erase everything and start over? Or do I need to buy a new harddrive and store the original one forever? I would prefer to record over the oldest data if this is an option. My guess is that if I haven't needed something for the past year or so, then I probably don't need it.

Any insight would be appreciated,


iMac, Mac OS X (10.5.1), 2.4 GHz Core 2 Duo, 2 GB 667 MHz DDR2 SDRAM
  • Gabizou Level 1 (115 points)
    As the external drive becomes full, Time Machine will delete backups that have barely any information that has changed, and in doing so, it will condense all older data into nothing and it will be deleted. When Time Machine notices that the drive is full, it doesn't bother to ask you if you want to erase older backups, as to which would become a problem where people would erase some data that Time Machine needs (it becomes picky and will become panicky if something is changed by another user(ie you)) and all it does is alert you that it will erase backups and it will keep on trucking with automated backups for life.

    This reason is that Apple decided to make Time Machine a User Friendly application that automatically knows what to do in all cases (within some exceptions), and in that process, Time Machine will constantly be determining what backups to erase and what backups not to erase.

    In Conclusion (sorry to be so wordy), All you need to do is to just go on with your life and Time Machine will delete old backups when it needs to. If you have files that you know you want to keep, store them in a separate external hard drive and only turn that drive on when you need to use it.
  • D. Fraser Level 3 (560 points)
    Here in the [101|http://docs.info.apple.com/article.html?path=Mac/10.5/en/15137.html] on your question
  • Jeremy P Level 3 (740 points)
    There is a Time Machine preference setting to allow you to either receive a warning when Time Machine has run out of room and is about to delete old backups or just let Time Machine go ahead and do its thing.
  • Lincoln Nymeyer Level 2 (295 points)
    Thank you Gabizou, D. Fraser, and Jeremy P,
    This is exactly what I needed to know. Now I have another question, and I don't know if I should start another "string"? My wife sees my Time Machine program and she is very jealous. Is there anything similar to Time Machine for a PC? (she has a Dell desktop).

  • pvonk Level 6 (13,705 points)
    I suspect the answer is yes and no. TM works the way it does because the Leopard operating system was designed to support it. It's been a while since I switched to Macs, but my Vista friend tells me there is some backup mechanism on Vista - not really sure whether Vista provides low level support for it.

    However, any other solutions on a PC (third party apps) would not have the tight integration with the operating system that TM has (since XP doesn't have the support), so they may not work as well. I do recall years ago (or more) that I had a PC app that did constant backups of all changed files, but that didn't work quite so well. Not sure if the product is still around (don't recall its name).
  • D. Fraser Level 3 (560 points)
    This actually might be a better question to post somewhere else entirely. Maybe on a PC-centric site. You could try to post another thread here, I just know if it is the right place to do it. I wish I could help you more but the only time I need to be in Windows is to check IE compatibility with my websites. .

    Anyway, good luck finding a solution. (and thanks for the solved star)

  • Joe Cowley Level 3 (550 points)
    Not wishing to enter a Windows discussion, but does not System Restore perform a similar function - albeit less sophisticatedly - as Time Machine?

  • William Beem Level 1 (20 points)
    Wouldn't that be an intelligent thing to do? I think so. Unfortunately, that's not the behavior I've seen from Time Machine. The first warning I receive tells me that Time Machine has already deleted my backup and it starts fresh with new ones. It happens once a month for me.

    So what happens if I need to restore something from a day or week before? I'm screwed. Time Machine has already DELETED MY BACKUPS before I get a chance to point it to another drive or take any kind of action.

    This is a great concept that is utterly RUINED by a stupid implementation.
  • Joe Cowley Level 3 (550 points)
    William, surely the length of time backups are kept depends on the total GB's backed up and the size, in GB terms, of the external drive used. And, if you select the option, you will know when TM starts deleting the oldest backup.

    On the above basis then, you could have weeks or even months of backups and what's the chances of you wanting a file from one of your oldest backups?

  • William Beem Level 1 (20 points)
    I think you're missing the point. Once it deletes ALL YOUR BACKUP FILES, you only have a backup that's a few minutes old. It isn't just rolling off the stuff at the end. I'd be fine with that. It's telling me that the oldest backup I can use in Time Machine is only an hour old.

    I found that some messages in E-Mail were nothing more than headers. The content wasn't in my database. When I tried to recover them, my backup wasn't old enough to go back a few weeks to reclaim those message that were older. Time Machine screwed me. That data is gone and will never come back.

    That's the flaw. If you don't realize that you need to restore something until after Time Machine empties its guts of your data, then it is completely gone and useless.