Time Machine FAQ

Discussion in 'macOS' started by atszyman, Aug 8, 2006.

  1. atszyman macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    This thread/initial post was started shortly after TM was announced and intended to stop many threads with basically the same questions from popping up all over. I myself have not yet used TM so the questions/answers are based on the best data I had available at the time of last edit. I know that some of it has been proven wrong. If you have corrections you can PM me and I will do my best to correct errors as they are indicated. Thanks.

    All answers are based on the information available here, here, and here (thanks applerocks).

    TM = Time Machine
    BUD = Backup drive
    HD = Hard Drive

    1) How does TM work?

    Time machine performs an automatic daily backup of your HD to an external drive or server. Every day at a set time (default of midnight) the OS will create a snapshot of your HD. The OS only updates things that have changed since yesterday so the amount of space taken up is minimized. If you accidentally delete or change a file you did not intend to you can go back to a snapshot of your drive for any given day. Also as you make changes Leopard notifies TM and keeps track of only the changes to the files it will also periodically save the changed files to the backup drive, provided the backup is connected.

    2) Won't Time Machine fill up my HD?

    No. Time Machine performs a daily backup to a separate hard drive/storage device. It does not keep multiple copies of the files on your main HD. It keeps track of changes as you make them but does not create multiple copies of the file (think undo). It will periodically copy the changed file to your BUD if connected. I would guess that there is a finite buffer for recent changes if you are not working with the backup drive attached.

    3) What if I create and delete a file between backups? Is there a way to recover that file?

    This is still unclear. The Finder notifies TM of changes to a file. As you work (if you are connected to your BUD) the changed files are copied to the backup every so often. If you create and delete a file between writes to the BUD it is possible that the file is completely lost, or if you are not connected to your backup 24/7 and you create and delete a file in the time you are not connected it is possible that it is lost. At the end of the day the changes are coalesced into a final image for that day. Provided you are connected to your BUD and have the file existing long enough you should be OK.

    4) Do I have to back up everything?

    No. You can tell Time Machine which items to ignore during backup.

    5) How is time machine different from other backup utilities?

    TM keeps track of all the changes made on your drive in a given day and only backs up the changes. Utilizing this information it minimizes the space required for multiple backups and allows you to store further back in time. Most other utilities would require a daily, complete HD backup which would consume a lot of space, and a simple daily backup to the same location would not allow you to go back more than one day. TM allows you to go back and see exactly how your HD looked on any given day (provided you had the BUD connected that day). Given enough storage and minimal changes you may be able to go all the way back to the day you received your computer (for Leopard pre-installs) or the day you installed Leopard. TM creates a history of backups in one place so you can get a previous version of the file, where most other backup utilities would require multiple separate backups in order to walk back to a version of a file before the last backup. Some third party utilities, like Retrospect, already offer some of this functionality.

    6) How far back can TM go?

    Screenshots indicate that there are options for: Indefinitely, At least 1 month, At least 3 months, At least 6 months, At least 1 year. (Thanks shrimpdesign). It remains unknown if you can specify a maximum backup size or how that might be related to the duration of the backup.

    7a) When Apple say backed up to a server do they just mean any network storage?
    No, It must be a server or drive. It cannot just a remote drive on the network as 10.5 still sees the remote drive as a folder AFP mount.

    7b) Can this backup be done to another Mac's HDD home server for my laptop)?
    If the remote drive is partitioned and dedicated to TM, as in Target drive mode. So kinda, this is only true if it will handle partitions which I can't remember.

    8) Can it be done over wifi / network, .mac?
    wifi / network yes to a server, .mac no. (7a, 7b, & 8 provided by Fearless Leader)

    9) Any idea of what the server has to be running for it to work with TM

    "It will work with any non-bootable volume formatted in Apple’s HFS Extended format. That drive can be stowed inside a mac pro, attached on the end of a FireWire or USB cable, or even mounted on your desktop from elsewhere on your network. The one big catch is, the entire volume must be devoted to Time Machine—you can’t just stow Time Machine files inside a folder on a larger volume." link

    10) Can you choose to permanently delete something?

    Since the backup is done to an external drive and is intended as a backup there is no permanent delete until the time limit of the backup is reached. See #3 for how changes are tracked. If your BUD is not connected you may permanently lose any files created and deleted during this time period depending on how TM behaves when no BUD is present.

    11) Will TM slow down everything because it constantly backs up?

    Since it's only logging changes I would not expect it to slow down anything more than Spotlight did.

    12a) What happens to my TM backup when i restore my system via recloning with super duper?
    12b) What happens when I sync macs?

    This one could go a couple of different ways. If the change tracking system is part of the main OS then you could end up in a situation where after cloning, only the files indicates as changed on the clone would get backed up which would mess with the timeline considerably. If the system somehow does a compare to the TM backup then all should be OK. You're first backup after cloning would be akin to a complete HD backup, and if you go back one day you would see the machine as it existed before cloning. At this point with the information available I cannot say how this will work. I'm sure Apple would prefer that you use TM for system restores in order to avoid this potential issue, you may also be able to use TM to make clones as well.

    13) Is TM searchable?

    In the demo at WWDC a search is shown using Address Book to find a particular contact that was deleted. It is unclear if or how this works in Finder. Can you search only a folder or the entire HD for a particular file? We don't know yet.

    14) Can recover just some records for an application like Address Book to merge with any new data?

    Yes or no, depending on how the application takes advantage of TM. In the demo Address Book is specifically used to find a deleted record and restore it, but it will be up to developers how they want to implement this feature in their app.

    15) Can the Backup time interval be changed?

    Everything I have seen indicates that it backs up once a day at a user specified time. I have not seen anything where they mention being able to back up more or less often than daily. Apple's website claims "Since backups are stored on your device by date" so it is probable that the backup interval cannot be shorter than a day.

    16a) Does TM encrypt the backup data?
    It can, but doesn't automatically.

    16b) Is the TM backup accessible via the Finder?
    yes, as long as A) Not encrypted, B) you can wade through the weird file structure.(16 a&b answered by Fearless Leader)

    17) Does TM take over a backup volume?

    Yes. However it will only take over one mounted volume, if you have a large disk that you would like to use for multiple backups you can partition it so each backup has it's own volume for TM.

    18) How does TM work when no BUD is connected?

    I have no idea. It is possible that anything done in these intervals is lost forever, it is also possible that Loepard keeps a rolling buffer of changes utilizing free HD space in the background to try and save as much information as possible until the BUD is reconnected.

    19) Does TM makes bootable backups?

    I'm going to guess that due to the way TM keeps track of how your HD looked through history I believe that the TM backup is some large database of files/folders. This would mean it's probably not bootable but the Leopard install CD has an option to restore a disk from TM BUD (confirmed by c-Row).

    20) Will TM work with non-core image video cards/integrated graphics?

    TM functionality has nothing to do with the video card in the system if Leopard supports the system TM will work however the animations and visual effects may be limited on some systems.

    21) Does TM make mirrored, and other advanced RAID arrays for data recovery obsolete?

    A RAID array set up for data recovery will not be made obsolete by TM. Since TM is not constantly writing to the BUD and it is unclear what happens when no BUD is connectd the RAID array is still one of the best methods for capturing everything in the event of a single HD failure.

    22) Can TM restore system applications after and OS re-install?
    TM can reinstall everything if you reinstalled the OS. (answer from Fearless Leader)
  2. spicyapple macrumors 68000


    Jul 20, 2006
    Excellent post, atszyman! (your name a little hard to type, :) )

    This should be a sticky. :cool:
  3. cube macrumors G4

    May 10, 2004
    Nothing new here. Retrospect and BRU can also do incremental backups, for example.
  4. risc macrumors 68030


    Jul 23, 2004
    Melbourne, Australia
    When Apple say backed up to a server do they just mean any network storage?
  5. atszyman thread starter macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    But incremental backups aren't the innovation. It's the fact that when an incremental backup is done the previous version of the file is still available as well. Most incremental backup utilities I've seen overwrite the file which means you can only go back to your last backup, or require going back to one of many previous backups if you are looking for a particular day's version of a file. With Time machine if you edit the same file every day for a week and back up to the same drive every night, you can still get back the file from last week before you did any editing. I looked at BRU and Retrospect and cannot find this feature mentioned in any of their literature.
  6. aswitcher macrumors 603


    Oct 8, 2003
    Canberra OZ
    Can this backup be done to another Mac's HDD 9home server for my laptop)?

    Can it be done over wifi / network?

    Can you choose to permanently delete something?
  7. andiwm2003 macrumors 601


    Mar 29, 2004
    Boston, MA
    looking at my data usage i predict that the sales for 500GB external HD's will go up a lot.

    the problem with time machine is that you still need to be very organized. you need to exclude podcasts and video podcasts and audiobooks. you need to figure out how to back up iPhoto because 50% of my pics need to be deleted forever anyway. no reason to fill up my external HD with out of focus pics. you should exclude video projects in the GB size. what about temporary cd burn folders? emails? what happens to my time machine backup when i restore my system via recloning with super duper? what happens when i sync macs? to me it seems you still will need to organize your backup system unless you don't mind filling up external HD's.

    will time machine slow down everything because it constantly backs up?
  8. cube macrumors G4

    May 10, 2004
    I use Retrospect and it does support multiple versions, of course. You browse/search the catalog for the item you want to recover, and the different versions appear listed with their date. This is way better that some silly warp drive interface.

    Where Time Machine comes in handy is where you don't know which files you have to recover for an application like Address Book or iPhoto, as shown. But there still should be a tabular alternative to the eye candy.

    One thing which was not clear in the demo is if you can recover just some records for an application like Address Book to merge with any new data. This would be cool, but it's not obvios what happened there. For iPhoto, he selected the photos to recover, so it seems there was a merge.

    With Retrospect it is possible to specify many types of exclusion rules, with Time Machine, it's not clear that one can do anything like that.

    Time Machine doesn't backup continously. It backs up only daily. It's not clear if one can backup at shorter intervals, like hourly.
  9. atszyman thread starter macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    Thanks for the info on Retrospect, sounds like a nice utility. However it looks like Time Machine can search as well, provided you know which directory to search in, although the demo does it in Address Book, not Finder.

    Actually application specific data (Address Book records) depends on how the application is implemented. The demo shows how to search for a contact and restore it to Address Book, merging it with the existing contacts.

    On the page I linked to in the original post:

    "By default, Time Machine backs up your entire system. But you can also select items you’d rather not back up."


    I've also added questions I've seen up to this point if the answer isn't there, or is unclear.
  10. cube macrumors G4

    May 10, 2004
    It was the Address Book demo where one can't tell if he recovered only one record or the whole book. He should have told specifically.

    Yeah. I saw that, but it's not clear how smart the rules can be.
  11. atszyman thread starter macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    I'm convinced he restored only that record. If not, it is a very poor implementation if you have to destroy all your new records to retrieve one old one.

    We suffered a semantics argument there. You said

    I would argue that you can do "something" like that as indicated on Apple's site however the granularity and how it's implemented is unknown.
  12. Chundles macrumors G4


    Jul 4, 2005
    When he did the Address Book search, there were two options on the bottom right, "Restore All" and "Restore" he clicked "Restore" - I'm pretty sure it only added that one entry.

    You can see it again on the sneak peak video.

    You'll notice it's performing the Spotlight search on every instance going into the past. Not only is that damned cool, it means there was only one entry there that he could've restored.
  13. cube macrumors G4

    May 10, 2004
    Well, normal backup restores complete files, not records, so if Address Book stores all the contacts in one big file, it would be the usual business. What would be absolutely terrible would be to ovewrite the current book and not being able to open a different one and manually copy the records.

    But with these merge capabilities, I would be interested to get a second, big hard disk and use it as a secondary backup. The primary continuing to be tapes with another tool.

    Of course, now that Apple is pushing, I would prefer for EMC to improve Retrospect to do something better: use the backup hard disk as a staging area (keeping as little as the last version of each file), and store everything for real in tapes. But I doubt the system has an API for 3rd party utilities to do merging as Time Machine.

    Ah, OK. I couldn't see where the heck was this restore button that he mentioned. I didn't see those buttons at all.
  14. atszyman thread starter macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    But on their site:

    So the specific record restore is going to be Application dependent, not a limitation of Time Machine. If they had done the Address Book through Finder I agree that they would have to restore the whole database, eliminating updates that occurred after the last backup, but since they did it in Address Book I believe that AB is accessing the TM facilities to handle individual record backups, much like iPhoto.
  15. shrimpdesign macrumors 6502a


    Dec 9, 2005

    A screen shot from the Time Machine prefs. More at:
  16. gauchogolfer macrumors 603


    Jan 28, 2005
    American Riviera
    ^^ Thanks for the link, there are some cool screenshots there. How about this one:

    Is it currently possible to put different users in groups like this and apply permissions/access across all of them at once? Sounds cool.
  17. atszyman thread starter macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    Thanks for the info, I've updated the Q:A in the first post.
  18. Sky Blue Guest

    Sky Blue

    Jan 8, 2005
    Someone proposed in another thread (Leopard preview, I think) that the external drive that TM uses could be used solely by TM and nothing else. Any truth in this?
  19. atszyman thread starter macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    I have not seen any information that would confirm or deny this. However the mention of backing up to a Server or other Volume makes me believe that network mounted directories would also work for TM which would indicate that it doesn't completely hijack a drive. It is also very likely that someone would use a large external HD or array of HDs to backup multiple computers so I can't see Apple letting TM hijack an entire drive for a single system.
  20. jsw Moderator emeritus


    Mar 16, 2004
    Andover, MA
    atszyman, thanks for setting up this FAQ. As you find other threads about Time Machine (not that it'll be difficult), please feel free to ensure that you've answered or at least noted the appropriate questions, possibly adding them to the FAQ, and then PM me with a link to that thread. I'll then close it with a link to here.

    I tend to be sporadic with my time here - I'll be on for hours, then away for hours, so don't think I'm ignoring you if I don't respond immediately. I think I might have left a Buddy List up on a Mac at home, so it might seem that I'm always online, but I won't be.
  21. seany916 macrumors 6502

    Jun 26, 2006
    Southern California
    Thank you atszyman. Very helpful thread/post. :)
  22. 7on macrumors 601


    Nov 9, 2003
    Dress Rosa
    All I see this as is a glorified version of Backup.app included with .Mac. I just used Backup this morning to restore my address book after my Macbook had an infamous turn off. It is useful and should be pretty fun to use (though I hope it's not at midnight because my backups are scheduled at the end of work). I like to keep my backups at a separate location if possible.
  23. ~Shard~ macrumors P6


    Jun 4, 2003
    Just wanted to throw in my thanks as well atszyman, excellent thread. I'm one of those annoying guys who has been asking Time Machine questions in multiple threads, so I'm glad I found this one. o ;)
  24. atszyman thread starter macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    Will do. Likewise if anyone here sees a question that is not addressed/answered but you would like to see added you can PM me and I will get to it ASAP.
  25. Macmadant macrumors 6502a

    Jun 4, 2005

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