Time Machine question?

Posted:
in macOS edited January 2014
Apple says Time Machine automatically backs up your Mac. "So if you change a file, that file is automatically backed up."



How can a file be automatically backed up, if your external hard drive isn't plugged into your Mac and powered on the whole time?

/I'm asking this because I don't want to leave me external hard drive on the whole time, as it wastes energy, uses up a USB port, and most importantly shortens its life.



If by some miracle of science Leopard uses a fully bootable ZFS file system, would my information take up any less hard drive space than it currently does?

Comments

  • Reply 1 of 16
    Quote:
    Originally Posted by Ireland View Post


    Apple says Time Machine automatically backs up your Mac. "So if you change a file, that file is automatically backed up."



    How can a file be automatically backed up, if your external hard drive isn't plugged into your Mac and powered on the whole time?

    /I'm asking this because I don't want to leave me external hard drive on the whole time, as it wastes energy, uses up a USB port, and most importantly shortens its life.



    If by some miracle of science Leopard uses a fully bootable ZFS file system, would my information take up any less hard drive space than it currently does?



    It automatically backs up to your external drive. Otherwise, no flux capacitor for you!
  • Reply 2 of 16
    irelandireland Posts: 17,798member
    Quote:
    Originally Posted by SpamSandwich View Post


    It automatically backs up to your external drive.



    Who in the name of God is going to leave their external hard drive plugged in and turned on the whole time?
  • Reply 3 of 16
    Quote:
    Originally Posted by Ireland View Post


    Who in the name of God is going to leave their external hard drive plugged in and turned on the whole time?



    Actually, I have a 200GB LaCie external and a 60GB Que! drive I have to leave on all the time.
  • Reply 4 of 16
    tednditedndi Posts: 1,921member
    Perhaps the deltas are routinely backed up using .mac and zfs.



    When you reconnect your external hdd the deltas are copied there and then.



    I don't think that the deltas would in fact take up all that much space.
  • Reply 5 of 16
    irelandireland Posts: 17,798member
    Quote:
    Originally Posted by TednDi View Post


    Perhaps the deltas are routinely backed up using .mac and zfs.



    When you reconnect your external hdd the deltas are copied there and then.



    I don't think that the deltas would in fact take up all that much space.



    deltas?
  • Reply 6 of 16
    Quote:
    Originally Posted by Ireland View Post


    deltas?



    Changes in state.
  • Reply 7 of 16
    tednditedndi Posts: 1,921member
    Quote:
    Originally Posted by Ireland View Post


    deltas?



    Delta is a change. In zfs, from what I gather, the changes are saved and not the original file. Thus in a backup you would have the original file and the slew of deltas that are generated every time files are changed. This is why zfs is so important.



    So, in the case of ongoing backups only the deltas need to be saved. .mac could be used for such a thing keeping a cache of backups until you could get your external drive connected.



    There are many more knowledgeable sources here on the boards. Someone please jump in if I am mistaken.
  • Reply 8 of 16
    brussellbrussell Posts: 9,812member
    There will be not only a regular timed backup, but also a manual backup, where you plug in your drive and click "Back Up Now."
  • Reply 9 of 16
    MarvinMarvin Posts: 15,280moderator
    I think most people will use a manual backup because an automatic one would put too much load on the system always reading and writing. I wonder how an automatic feature will work with Spotlight if people forget to tun off indexing and the launchservices database.
  • Reply 10 of 16
    tednditedndi Posts: 1,921member
    Quote:
    Originally Posted by Marvin View Post


    I think most people will use a manual backup because an automatic one would put too much load on the system always reading and writing. I wonder how an automatic feature will work with Spotlight if people forget to tun off indexing and the launchservices database.





    Actually with zfs it wouldn't as only the actual file changes would be recorded. The files themselves would remain the changes would be stored. Think iphoto and aperture and the non destructive file editing. That will be zfs and time machine.



    How often do you actually modify a file at any given time. For most of us that would be a few times per hour or a few times per day. Mail for me is the most oft changing group of files. with e-mail going in and out.
  • Reply 11 of 16
    rongoldrongold Posts: 302member
    Quote:
    Originally Posted by Ireland View Post


    Who in the name of God is going to leave their external hard drive plugged in and turned on the whole time?



    I leave my WD 500GB triple-interface Pro Editions on all the time. They have some sort of power-savings mode though.
  • Reply 12 of 16
    wmfwmf Posts: 1,164member
    Time Machine does not use ZFS.



    When a scheduled (or manual) backup rolls around, Time Machine copies all the files that have been modified since the last backup. I think a lot of people are trying to make Time Machine more complicated than it is.
  • Reply 13 of 16
    tednditedndi Posts: 1,921member
    Quote:
    Originally Posted by wmf View Post


    Time Machine does not use ZFS.



    .



    So, why the hell will ZFS be rolled into OS X?



    Zfs lends itself to massive backup.
  • Reply 14 of 16
    Quote:
    Originally Posted by TednDi View Post


    So, why the hell will ZFS be rolled into OS X?



    Zfs lends itself to massive backup.



    Because, I dunno, ZFS has a lot of great things going for it?



    (Also, Time Machine works great on Leopard betas that don't have ZFS.)
  • Reply 15 of 16
    tednditedndi Posts: 1,921member
    Quote:
    Originally Posted by gregmightdothat View Post


    Because, I dunno, ZFS has a lot of great things going for it?



    (Also, Time Machine works great on Leopard betas that don't have ZFS.)



    So why then, roll ZFS into Leopard?





    Hell, non destructible files work great in Aperture under Tiger.



    Stop looking back and look a bit forward.



    The command line worked great in the apple ][



    Why upgrade?



    No, there is something here with ZFS.
  • Reply 16 of 16
    No one's looking back at anything.



    ZFS is amazing, for more reasons than just backup.



    That's why it's there.
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