Time Machine.. miracle app?

in General Discussion edited January 2014
I saw the stream and there is something I don't understand about Time Machine...

he says that "even if I lose the hard drive, I can still recover all my data"

I'm paraphrasing (the WWDC feed is down now, cant skip to it...)

How the hell can you possibly recover all your data from a hard drive that dies??? Or does he mean that "obviously" everyone has 2nd hard drive? I really dont get it.. the Apple page also doesnt clarify much

And. good god. How much space is it going to take!?!? I move about 5-10GB of data per DAY (downloads, content creation, etc), I'd run out of hard drive space in weeks despite having 2 x 400GB dirves.

Any further info from anyone?


  • Reply 1 of 17
    SpamSandwichSpamSandwich Posts: 33,407member
    Yes, it really is a miracle app.
  • Reply 2 of 17
    davegeedavegee Posts: 2,765member
    If you're thinking of relying on Time Machine to recover from a drive failure, a 2nd PHYSICAL hard drive is mandatory, no matter what Apple PR says.

    Oh sure I guess you could partition a drive into two logical partitions but if the drive (mechanically) bites the big one then both partitions will be lost. If however the drive has some kind of major corruption where a format will get you going again then I'd guess you could get away with a single drive...

    To be safe fork over the money for an extra drive. I can find 350GB SATA drives for under $100 all the time now (with no silly mail in rebates)

  • Reply 3 of 17
    kickahakickaha Posts: 8,760member
    Funny, I thought they were pretty clear... plug in a second drive, and it becomes available for Time Machine.

    ie, you still need a backup drive. (or a backup server, in MacOS X Server 10.5, but most folks won't have that...)
  • Reply 4 of 17
    placeboplacebo Posts: 5,767member
    It's dark magic and cannot be trusted.
  • Reply 5 of 17
    zozo Posts: 3,117member
    didint hear the part about "2nd drive"

    Still.. are the backups highly compressed or what?

    I stopped using .Mac Backup because I was auto backing up every day to my 2nd HD and by the end of a month I had no space left..

    So, yes, now I just manually backup my folders every few weeks...
  • Reply 6 of 17
    kickahakickaha Posts: 8,760member
    No idea on compression - I use a rotating fileset with rsync and hard links, and backup an 80GB drive to... an 80GB drive. Works well for up to about 10 sets. Most likely you can set the rolloff point, or it'll just silently remove the oldest (or maybe give it greater granularity?) when space gets tight.

    Too many questions, no answers.
  • Reply 7 of 17
    brussellbrussell Posts: 9,812member
    I bet it uses some type of tracking that will make it much more efficient than backing up each file every day. It will only record changes that are made. Of course, it will still take a lot of space, but I think it will be an efficient method of backing up data, if you choose to use it.
  • Reply 8 of 17
    kickahakickaha Posts: 8,760member
    Um, yeah, it's called incremental backup, and that's what I have in my setup.

    rsync only copies files that have changed. Hard links are used to make it *look* like every file was copied, but they take up almost no space. No compression needed, and it only copies the files that have changed.
  • Reply 9 of 17
    placeboplacebo Posts: 5,767member
    I think I'd only really trust that if it had the latest file PLUS the original file with incremental changes written on your harddrive. I guess that's how it works if it requires an extra HD; the first HD is just like it would be in Tiger, while the second has all the increments.
  • Reply 10 of 17
    kickahakickaha Posts: 8,760member
    Yup, exactly.

    If I change a file daily, and have daily backups, then I can flip back through today (on main HD), yesterday, the day before, the day before that, etc, and see each changed version. If I change a file weekly, I can *still* flip through daily backups, and it won't change - but it also doesn't take up umpteen copies of the same data - there's one copy of it, and umpteen hard links pointing to it. Hard links are like aliases, but really *ARE* files in their own right. (Voodoo. Just keep telling yourself it's happy shiny voodoo.)

    You just have to do it carefully - Time Machine really does feel like a simplified GUI version of that though.
  • Reply 11 of 17
    I kinda like it, as long as I can choose what I want backed up.
  • Reply 12 of 17
    kickahakickaha Posts: 8,760member
    Yup, that was mentioned too - you can specify folders (files?) to be exempt.
  • Reply 13 of 17
    placeboplacebo Posts: 5,767member
    Yeah, that's good, I'm not completely fascinated in hundreds of days of System folder... though come to think of it, that could come in handy.
  • Reply 14 of 17
    kickahakickaha Posts: 8,760member
    Yeah, especially since they aren't supposed to change.

    "Show me the latest change to /System... uh... I didn't update that day... er... problem?"
  • Reply 15 of 17
    From Apple's site: (http://www.apple.com/macosx/leopard/timemachine.html)
    You back up your system regularly, right? Well, you would. If you had a better way to do it. With Mac OS X Leopard and Time Machine, not only can you back up and preserve everything on your Mac ? including priceless digital photos, music, movies, and documents ? without lifting a finger, you can go back in time to recover anything you?ve ever backed up.

    Set it, then forget it

    The first time you attach an external drive to a Mac running Mac OS X Leopard, Time Machine asks if you?d like to back up to that drive. Set up the drive and Time Machine takes care of everything else, automatically, in the background, so you can get on with your digital life.

    Back up everything

    Right from the start, Time Machine in Mac OS X Leopard makes a complete backup of all the files on your system. That includes your system files, applications, accounts, preferences, music, photos, movies, documents ? everything you keep on your Mac. As you make changes, Time Machine only backs up what changes, all the while maintaining a comprehensive layout of your system. That way, Time Machine minimizes the space required on your backup device. Since backups are stored on your device by date, you can browse through your entire system as it appeared on any date. And that?s what makes Time Machine different from any backup application you?ve ever tried.

    Go back in time

    With Time Machine, you can restore your whole system from any past backups and peruse the past with ease. Can?t find a file you want? Enter Time Machine?s time-based browser to see a snapshot of how your entire system looked on any given day ? file by file. When you find the file you want, just select it and restore it. Time Machine brings it into the present. You can do the same with a group of files, whole folders, even your entire system. With a single click.
  • Reply 16 of 17
    dfilerdfiler Posts: 3,420member
    Originally Posted by Kickaha

    No idea on compression - I use a rotating fileset with rsync and hard links, and backup an 80GB drive to... an 80GB drive. Works well for up to about 10 sets. Most likely you can set the rolloff point, or it'll just silently remove the oldest (or maybe give it greater granularity?) when space gets tight.

    rsync is mind-bogglingly powerful isn't it? We use it and hardlinks to back up our linux servers.

    Only the modified blocks of files need to be written over the network. Given our usage patterns, a week's worth of daily snapshots need only 1.5 times the space of the original data. The data is uncompressed and access to it is just as quick as for "real" files. Once we realized this, we decided to go for hourly backups as well. With 24 hourly snapshots from the previous 24 hours, we still use less than 2x the storage as the live data.

    I can't wait to find out what apple's implementation is based on (if anything). I'm guessing that time machine is built atop a couple mature/legacy command line utilities...
  • Reply 17 of 17
    I'd definitely back up to an external drive in case of mechanical failure of your primary drive. Then Time Machine should work wonders for restoration.
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