Using multiple backup drives with Time Machine

Update: Apple have finally added proper support for this!

Inspired by Jeff Atwood’s post a few weeks ago, last week I finally set up an offsite backup strategy. I picked up two 320gb Hard Drives + a firewire caddy for each (A$300 total, ouch) and am now rotating them to work weekly. One of the reasons I’m finally doing this is the ease of creating a bootable backup compared to doing it on Windows; and the other was that Time Machine makes general backups easy. Of course after I bought the second drive, I discovered that using Time Machine with multiple drives isn’t as easy as it could be.

There is absolutely nothing wrong with multiple drives, and Time Machine does support it – to the point where in 10.5.2 it will happily let you choose which TM drive to browse without first switching the target backup drive. But there’s a boatload of misinformation out on the net so I waited all week to post this and make sure my assumptions were correct. Apple has made a very robust backup solution. If you’re doing offsite backups it is not 100% automated, but that is a trade off for more flexibility.

I started with my two drives, and created an initial time machine backup on both. This gave me an immediate off-site backup rather than sitting on it for a week. I even ran a stress test – in the middle of the initial sync on the second drive I ejected it. Time machine stopped, and when I plugged the drive back in it did a quick scan then copied only what was left of the initial sync. Works perfectly.

Friday is my offsite swap day, so I arrived home this afternoon with my second drive and plugged it in. This is where time machine becomes a minor chore – you have to manually change the backup drive. Once that was done, it spent 5 minutes (according to the system log) comparing the 30gb main drive to the backup and then did a nice big 14gb copy (I migrated iTunes during the week). This proves my initial assumption that each individual drive will work exactly the same as if you had one backup drive and only plugged it in for one out of every two weeks; TM scans for old backups on the swapped drive with no complaints. If I need a file that was deleted while backing up onto the drive currently offsite, I can either wait until my next swap or plug it into one of the macs at work.

The final step in the process was creating a bootable backup. I know TM backups can be restored, and despite buying FireWire enclosures to allow PPC bootingI can’t even boot from these firewire drives on the iBook – but I’m definitely buying a mac mini in the next 3-6 months and at that point I want to have the option to instantly boot from the backup (which I’m doing nightly).

I know backup boot works after watching AJ boot from his Carbon Copy Cloner backup when he sent his laptop in for repair, but having analysed the feature sets and perceived reliability of the backups I forked out the cash for SuperDuper!. CCC certainly looks fine and has better scheduling options, but after trialling SuperDuper! it was just so much more obvious how to do a smart backup and it seems to have better support for backing up the currently booted partition.

One day I might even use it’s ability to create the bootable backup onto the Time Machine partition; but for now I have a backup of Mum’s data I need to store on that drive and it only supports ignoring the Time Machine folder, nothing else.

I’ll take a pic of frankenlaptop soon, but I’m waiting on a USB soundcard which will add to the plethora of USB devices it’s using and be the final key in my dual machine setup πŸ˜€

70 thoughts on “Using multiple backup drives with Time Machine

  1. Hi
    I have two hard drives on a Mac using OX 10.5.2 and want to back each of them up to two separate external hard drives using Timemachine. Can’t see how to achieve this in the preferences. Any ideas on any easy automatic solution to this?

  2. Unfortunately that isn’t possible. While Time Machine will let you switch target drives, it backs up the entire system (minus any exclusions) to the target drive each time.

    You’ll have to use a normal backup process with either CCC or SuperDuper.

    1. > While Time Machine will let you switch target drives,
      > it backs up the entire system (minus any exclusions)
      > to the target drive each time.

      That’s not true. The initial backups will indeed be full backups. On each disk, Time Machine stores the FSEventID counter it used for that backup. You can safely swap drives, and given that ID Time Machine will know what is missing on that specific drive. (True, this does not allow for backing up differents disks to different backups without changing the plist file.)

      See also the comments at for more details.

      1. You totally missed the comment I was replying to (threaded comments are a recent thing and that comment is 16 months old). Congratulations for linking to an article that says the same thing my post does. I’ve got half a mind to accuse you of spamming and delete the link.

        Yes, when you switch target drives it does an incremental backup. That’s what my post is about. However, it does back up the full system to both drives.

        This comment is asking about two source drives, and backing up each to their own TM drive on one system.

  3. Hey, thanks for the info on this. I hadn’t realized that I could backup to two drives. Now I’m backing up my MBP to a network volume at work as well as a portable drive at home. Sweet!

  4. It works to a point, but there’s a bit of weirdness after you restore from one of the time machine backups. I’ll blog more about that soon.

  5. Spyder, thanks for the post.

    having read it, I was literally about to create a second backup drive when i read your comment directly above (#4).

    Is the ‘bit of weirdness’ sufficiently wierd that you would *not* recommend using two backup drives with Time Machine?

  6. Oh it’s nothing to worry about – I had to restore my system from a TM backup and while everything seemed normal, when I switched drives it did a complete backup. Makes sense I guess, it updates the TM backup that was used to restore but not the other drive so it thinks everything on your system is new.

    Considering this only happens if you need to restore an entire system, I don’t think it’s that much of a problem and still use two drives myself.

  7. I’ve been using two drives for Time Machine for a while now and it works fine. I have a drive at home that I call (funnily enough) “Backup [home]” and a drive at work called (you guessed it) “Backup [work]”.
    I just change the target drive in Time Machine preferences, depending on whether I’m at home or work.
    I’ve often wondered though, what would happen if I called both drives simply “Backup”. Would Time Machine spit the dummy and get confused?
    I guess this depends on where TM keeps it’s database… on the source machine or on the backup drive. If it’s the latter, it should work (comparing the source volume with the backup database on the relevant backup volume).
    If however, the backup database is kept on the source machine it will get confused when it compares the database with the backup volume and the contents are different.
    If it were to work though I wouldn’t have to keep changing the target drive in TM prefs.
    Anyone have any thoughts?

    1. Did you ever try having both your home and office disk with the same volume name, so you didn’t have to change preferences every time?

      Tx, -CR

      1. Hi Charles,

        I didn’t notice your comment way up here – maybe threaded comments aren’t the best idea after all πŸ™‚

        I did try both with the same name but it doesn’t work. With the second drive plugged in Time Machine will attempt to backup but fail. The Console revealed that it uses not only the drive name but the drive GUID to identify the backup target; unfortunately all of the UI relies soley on the drive name.

        So I went back to different names because I had to change preferences anyway!

      2. At the end of the day, IMO it’s not that much hassle to pick a new TM target drive whenever you swap (even if it’s weekly). I actually prefer having two separate labels now; it makes it easier to tell them apart when I have them in the same room or plugged into the same computer (as rare as that occurrence is).

  8. I created two different drive names as well, but that was more out of habit as I started with both drives connected at the same time.

    The “database” is stored on the backup drive, but I somehow doubt it uses the drive name as the indicator of where it backs up to. Think of what would happen if you plug both drives in at the same time πŸ™‚

  9. I’m doing this with two 1TB FreeAgent Pro drives. I got so tired of multiple brands of USB/FW enclosure failing or acting strange. The Seagates are sold as a drive and enclosure in one unit warranted for 5 years, with USB, FW, and ESATA out. They have a feel of quality engineering about them and they haven’t missed a beat. Not like my box full of broken enclosures…

  10. hi… i am hoping that you can help me? i hate to sound naive… but… i am looking to do what you have done…. i have a laptop… and a usb hard drive that i use for back up at while i am traveling for work (which is sometimes 40% of the time)…. then i have a airport extreme at home and have another drive connected to that to be used for back up… the problem is when i try and switch drives for the back up time machine wants to start over… how do i stop this and have it just add the new info? thanks in advance… josh

  11. For those looking for more complicated backup options than Time Machine provides, there is an open software solution: rsync-backup. I used this tool before 10.5 was released, and it has essentially the same functionality: it allows incremental backups. You lose the cool Time Machine history interface.

    It requires building the software, and writing your own cron scripts to do the backup regularly and delete old backups, but you can do as many different backups as you want to remote volumes or whatever.

    It’s the usual mac vs unix choice: have it easy or have it configurable.

    —Nathaniel Tagg

  12. “For those looking for more complicated backup options than Time Machine provides…” LOL!

    I haven’t gotten Time Machine because it’s way to complicated for me. Seriously, I don’t understand it to the point that I see no value in it whatsoever. I have a Mac Mini and a 250 GB Micronet MiniMate. I put everything up to and including a backup of my iTunes library on that drive: The MiniMate IS my Time Machine.

    If I don’t understand Time Machine, then from a purely practical standpoint, it has NOTHING to offer me that I can’t do just by simply dragging and dropping every folder I create onto the MiniMate’s firewire drive icon on my desktop.

    Some of us just want stuff to work intuitively, and can’t be bothered to have to learn something. Learning tech takes time, and my time is better spent working or just enjoying life.

    Hell, I threw an Airport Base Station in the trash one night because it exceeded my ten minute maximum time allotment to get it working.

    I’ve been using computers since we programmed them with punch cards (The first time I got a 5MB Winchester drive, I thought it would take a lifetime to fill it up), and by now everything should be sensed by the OS and it should set up to a working default automatically, and THEN offer you a settings menu with configuration options.

    Computers should also come on instantly like TV’s by now and have NO moving parts.

    I guess this has turned into a tech rant.


  13. I’m not defending Nathaniel, but you’re wrong.

    Time machine is too complicated? You must be overthinking it – you don’t have to go to the lengths that I did. You plug a drive in, OS X asks if you want to use it for backups. Nothing else required, nothing to learn, it just works. The OS does sense it automatically and then offers the ability to configure it later. One backup drive is all most people need.

    If you ignore the file history aspect or the ability to restore your entire machine state from TM then technically, yes, it achieves not much more than copying files there yourself. But the name of the game is convenience.

    I don’t have to remember to copy my iTunes folder to the external drive every time I change it. When I download a file to an obscure folder, I don’t have to remember to duplicate it on my backup drive. Copying files takes time, both in the need to babysit the copy process and actually remembering to do it.

    You note that your time is better spent on other things. Manually copying files takes far longer than spending 10 seconds to hit the “use this drive for time machine” button and never thinking about it again.

    I never used to bother with proper backups because copying files was a pain in the arse. Now I have a full system state backup that is updated hourly and I never have to think about it.

    If you’ve never lost a hard drive, you wouldn’t know the pain – believe me, if it ever happens you wouldn’t believe the time you can waste recreating files you forgot to back up manually. The small amount of time you spend now will definitely be worth it.

  14. Regarding the timemachine backups in different places and with different ‘exclusion lists’:

    TM saves its preferences (including the drive, and the exclusion list etc.) in com.appple.timemachine.plist. I use MarcoPolo to run a shellscript which, depending on the location, removes the preferences, and replaces them with the preferences (i.e. drive, exclusion) for the location i am at. I use this to backup only my work related things when at work on the network, and backup everything when at home and with my external harddrive.

    when the preferences are changed, you also need to run an applescript “Select Time Machine Volume Apple Script” for it to actually start backing up…maybe this helps.

  15. Hi Andy, hoping you could help me:

    I bought a 1TB external drive, thinking I could use TM to backup both my Mac and the 1TB external drive. Then I just read somewhere that TM will backup multiple drives but not the one TM is backing up on.

    Is there anyway TM can backup only its own drive?


  16. Ian – I may misunderstand you, but it sounds like you want to back up an external hard disk onto itself. This is redundant, as if the drive fails, then you would lose both the original files and the backup copies. You could try getting a smaller capacity hard disk (say 500GB), and using this for your external storage. You could then back this and your mac drive up on the 1TB drive.

  17. Anon,

    So there is a way to back up earlier backup drives? I was under the impression that TM only backs up the system drive, which is why I use another program to back up my back ups. Am I misunderstanding something? – Devo

  18. Anon,

    Never mind. I further investigated the preferences and answered my own question. For some reason, i didn’t think TM would backup any drive except the current system drive. For that reason, I found it only mildly impressive and limiting. Now I know better. Thanks for reading anyway.

  19. Sorry for not responding guys, I’ve been on holiday πŸ™‚

    Ian, as Anon said there is no point in backing up the TM drive to itself – it’s like backing up your computer’s hard drive to a folder on the same hard drive.

    Devo, trying to backup the backups is very difficult and almost equally pointless πŸ™‚

    The thing you are both missing is that while your backup drive can fail, the solution is not to attempt to backup the backup drive. The solution is to have multiple drives and only keep one at home.

    Because you’re not using a single backup drive 24/7 it will last longer, and offsite backups mean a fire at home won’t kill your data.

    The most paranoid case I’ve heard of is a guy with three drives. He keeps one at home, one at work and one in a safety deposit box. Rotates to work regularly and then once a month rotates to the deposit box.

    I don’t have anything that I would die without so I’m quite happy with my two drives and weekly rotation πŸ™‚

  20. Spyder,

    I agree with you on the virtues of an off site backup system. However, I work from home so it’s not as easy for me to do what you’re doing.

    I’ve entertained the idea of using my current safe deposit box at my bank but who wants to be running back and forth to the bank for a weekly rotating drive system. So that’s why I have been backing up my back ups.

    What I’m currently doing is using TM to back up my whole main drive to a FW drive. Using a program called BounceBack, I have also created a rock solid boot drive on a separate FW drive. Additionally, I have a 2.5TB array that backs up specific, important folders. It all works swimmingly.

    I’d be screwed if there were a fire but at least I feel like I’ve made an effort to protect my data in some logical way. If any of these drives were to go down to mechanical failure, I’d be covered by at least two more.

    Thanks for your ideas and thoughts on TM and off site back up systems. Perhaps in the future, I’ll be able to do something like that if I happen to make enough money to buy office space.

  21. I’m not advocating weekly backups to a deposit box either, monthly is about all I could stomach.

    It doesn’t have to be a workplace – could be a friend across town, even leaving it with a neighbor would (in most cases) protect your data from a fire πŸ˜‰

    If none of that is possible what I would do in your case is the 3-drive solution, but have the two not in storage on opposite sides of the house.

    But even that seems more paranoid than necessary πŸ™‚

  22. Hello Andy,

    Thank you for your very useful and interesting comments!

    I’m new to Mac (switched last month – very happy so far) and new to Time Machine. Not to backing-up though: I used to back up
    my PC; but not fail-safe as I only had one version, so I really want to do better from now onwards.

    I’ve just ordered a 2nd Mac (the same 2.0GHz 2GB RAM Mini, I’m not a heavy user), which I’d like to connect to the first Mini for sharing files, the (non-network USB) printer, and the internet (through the modem/NAT router provide by the ISP, either wirelessly, which I’d prefer to avoid, or by Ethernet, but that would use up the only ethernet port on the Mini thus preventing me linking the two Mini’s by gigabit ethernet without an additional switch).

    I’d like to add one external HD (for bulky data: mainly photos and music files), which I’d like to share, and another external HD for backing up both internal HDs as well as the first external HD; reading your system of rotation, I’d like to rotate the second (backup) external HD with a third external HD that I can store next-door (= my in-laws’ detached house).

    Re setting up Time Machine I have several questions:
    * Do I have to set up Time Machine on both Mac’s, whereby one of them will be set up to include the external ‘data’ HD in the backup?
    * Can both Time Machine’s backup to the same (rotating) external HD(s)? If so, do I need to partition these ext HDs first?

    I hope I have explained my (future) situation clearly, if not don’t hesitate to ask me more details.

    Thanks in advance for any suggestions/relies!

    PS: Does the above sound the best/simplest/most reliable way of linking/sharing both Mac’s, the printer, the ‘data’ external HD, and the internet?

  23. Glad I could help, Peter πŸ™‚

    For starters, doesn’t the modem/router have a switch built in? Mine has 5 network ports, I thought all modems did these days. It probably won’t be gigabit, but photos and music tend to transfer across 100mbit networks reasonably quickly and it would be easier than using wireless.

    You will have to set up Time Machine on both Macs. Backing up the external drive will only work if it uses a Mac format (HFS) partition; TM refuses to backup my FAT32 drive. In simple terms, if a windows computer can read it then TM can’t back it up. You can pick Mac or DOS format when formatting the drive.

    I recommend only backing up the external drive on one computer – if you add it to Time Machine on both computers it will be backed up twice. You could always leave it permanently on one computer and share via the network, but I don’t have enough details about your use case to really recommend one way or the other.

    Both machines can backup to the same drive(s). Time Machine uses a separate folder for each computer backed up, sharing backup drives is a built-in part of the system. The only problem you will have to swap the backup drive between the computers manually.

    You can’t backup over the network, at least not easily, without a time capsule. You will have to remember to move the drive between computers as often as you want the backups to be refreshed. I wouldn’t go overboard though or you’ll get sick of it; unless you have super critical stuff once a day is plenty, maybe once every two days.

    Let me know if you have any other questions πŸ™‚

  24. Thanks for taking time for a detailed response, Andy πŸ™‚

    I guess my modem/router is a switch too: it has (only) two (10/100 Mb/s) ethernet ports, so I’ll try that first.

    The external drive that I already got (the one with the music and photo files) is already formatted for Mac (I reformatted it when I hooked it up to the Mac the first time) and that works fine. Like you suggest, I’ll only back it up on/with one computer. This external drive will not be used heavily, so so I am thinking to leave it permanently linked to one computer and sharing it over the network; it’s mainly to avoid storing too much on the internal drives (and thus possibly and unnecessarily slowing the computers down). The most recent photo files I keep on the internal drive, as they are the most likely to be used, so over time I move them onto the external drive.

    I’m disappointed to read that backing up over the network is can’t be (easily) done without time capsule (which I’m not thinking of buying), because swapping over every (other) day is not so much a pain, but hard to remember…

    I have a question on how Time Machine works:
    * if I do a, say weekly, rotation with two external drives (one connected, in alternation, to the Macs, the other ‘stored’ next door) does the drive synchronize with the internal drive(s) each time you hook it up to Time Machine? With that I mean, for example: if I have delete files, or moved files to the external data drive, during week A, does TM change that on the second/other backup drive when I connected that one (at the beginning of week B)? Sorry if I don’t explain this very clear…

    Thanks again!

  25. Looks like I was wrong. Network backup does work between two macs, it’s just slow. There are some reports of issues but I think those were fixed so if you’re running the latest patches it will be ok. Personally I would stick with sneakernet for the speed, but the convenience of networking might outweigh the disadvantages for you.

    Basically, share the top-level folder of the drive, then on the other mac open that folder and it should appear in the Time Machine backup choices. Once selected, it will handle the rest as long as both machines are turned in. If you need any help with that let me know πŸ™‚

    Re your question, Time Machine doesn’t work like normal backups. It makes an entire copy of your hard drive every hour the disk is connected; using special tricks so that files which don’t change between backup runs don’t take up any extra space. It doesn’t matter if it has been a day or a week since the last backup, the current state of your hard drive becomes the latest backup.

    So yes deleted files will be deleted – but only in the latest backup, if you browse to an older backup (the Time Machine interface is great for this) then the deleted files will be available. This includes files moved to the external drive, they will still exist on the backups of the internal drive(s) until the Time Machine drive runs out of space. At which point the oldest backups are automatically deleted.

    This probably sounds more complicated than it is. The moral of the story is that if you want networked backups, you can have them. And you never need to worry about what Time Machine is backing up or if it has synchronized correctly, it really just works.

  26. Thanks again, Andy πŸ™‚

    As I’m currently living in rural France, with no ‘Macxperts’ around to help me out (and not having found much on the French forums yet), it’s great to find some expertise down-under!

    I’ll have a proper look at that Macworld article and wil let you know what I’m intending to do.

  27. Hi Andy,

    I’ve read the Macworld article and I’m inclined to go for a ‘simplified’ sneakernet-with-backup (rather than with rotation):

    * TM on the main Mac (the one that has the ext data USB hard drive and printer connected to it) backing up continuously onto the firewire drive A

    * TM on the second Mac (that’ll be used, by my wife, for occasional internet, email and office apps) backing up at regular intervals (say one or twice a week) onto the same firewire drive A; it’s not to big a deal if we’d loose up to one week of email; office apps data could be simply copied onto a USB stick that’s permanently plugged in) when there’s no ext drive available for TM. As the Mac’s will be placed (almost) next to each other, I’d only have to unplug the FW cable from the one Mac and plug it into the other Mac (and back after the second Mac’s backup has finished). This schedule & setup will greatly reduce the amount (un)plugging, thus reducing the wear & tear of both cable(s) and ports/connections. (the FW cable that came with the FW ext drive was already fitting too loosely on arrival, so had to be replaced for reliable usage!)

    * Both TM’s backing up on a second backup drive B (probably USB, so I don’t have to unplug the FW drive, just tell TM to temporarily use another drive as backup disk) at regular intervals (say once a week). In stead of rotating backup drives A and B I’m thinking of keeping drive A as the main/permanent backup drive and drive B as a ‘spare backup’ (stored next-door); that way I never have to unplug from the mains nor move drive A; I’d look for a non-mains portable drive for as the ‘spare backup’ disk (B).

    What do you think?

  28. I think you’re overcomplicating things to avoid rotation πŸ™‚

    I trust the macworld article, you should be fine with network backups instead of swapping the cable a couple of times a week. Apple specifically only allow network backups in cases where they have tested it to be reliable (at least by default).

    Losing a week’s email can be more painful than you think, and if you’re copying data to a USB stick manually you now have three backups to keep updated instead of two. That will get annoying very fast and then backup will become a chore. The trick with networked backups is to always use the same name for the shared folder; the second Mac won’t know the difference between drives on the main Mac.

    Moving onto rotation, if you’re bringing drive B into the mix at a regular interval why not rotate with drive A rather than sending drive B back to next door? Is it just because of the cable hassles?

    Admittedly I made sure my rotating backups use two identical caddys so swapping is dead simple. I never have to transport the power or firewire cables, just the drive. And very soon I’m going to switch to Seagate FreeAgent Go drives for my TM backups. They’re incredibly small, have just a single USB cable, and most importantly they are dead silent (my mac is in my bedroom πŸ˜‰ ).

    Above all, make sure your chosen solution is easy and painless. As soon as it becomes a chore you’ll resist doing it.

  29. Hi Andy,

    I’ve really enjoyed reading this thread and have learned a lot–thank you! I’m curious if you can come up with a better solution to my problem. First off, I’m not terribly paranoid and can live with one backup. My main drive is 1 TB and my backup drive is 400 MB. TM is working fine so far, but that’s only because I’m only using about 200 GB of the main drive right now. 150 GB of it is my iTunes library and it’s growing. I’m planning to plug in another drive (250 GB for now) and copy my iTunes library to it every couple weeks. I’ll exclude the iTunes folder from the regular TM backups.

    I would rather use TM to backup the iTunes folder to the separate drive, but I can’t figure out how to configure TM to do that. Any better ideas?

  30. Hi Doug,

    You are right to exclude the iTunes library from TM (although personally I still think multiple backups is the only way to fly). However, I don’t recommend using TM to backup the iTunes library to another machine. Reconfiguring every time would be a major pain in the arse.

    I recommend using Carbon Copy Cloner (donationware) or SuperDuper! ($28 ) instead. Both are much better for backing up a single folder, and while you will lose the historical backup feature of TM that doesn’t seem particularly critical for your iTunes library. Both also support multiple backup profiles, so if you decide to get a third drive for some other large folder (photos perhaps) then you can do that too. And both work just fine side-by-side with your normal Time Machine backups.

    I would suggest trying CCC first. It allows you to automatically backup whenever a particular drive is plugged in – that’s no use to me, but it sounds like exactly what you need.

  31. Hey Andy,

    Thanks much for the advice! I think I’ve got a system I like working now. My machine is a PowerMac G5, so leaving the external drive plugged in is no problem. I’m excluding my Music folder from the my Time Machine backup and now I only need a fairly small drive for this– just 49 GB of content. And I’m using cron to run rsync every night at 3am to synchronize my Music folder (and a folder called “big” that I keep other stuff like image files that don’t change much) to another drive. I don’t have any historical backup, but I don’t really need it here. rsync only copies what’s changed so it’s very efficient. In case anyone is interested, my crontab file looks like this:

    00 3 * * * /Users/dmckee/

    and my looks like:

    rsync -aq /Users/dmckee/Music /rsync-backups
    rsync -aq /Users/dmckee/big /rsync-backups

    And I have a symlink from /rsync-backups to the actual backup folder on the external drive:

    /rsync-backups@ -> /Volumes/WD400/rsync-backups/

    All the best, Doug

  32. Hi Doug,

    You didn’t tell me you had unix knowledge. Yes of course rsync is a neater set up for non-TM backups than one of the GUI tools and you’ll never know it’s running πŸ™‚

    The only thing that won’t handle is if the machine has gone to sleep. I worked around that by using Awaken to force my Mac to wake up just in time for the backups. Of course the schedule button in the Energy Saver preferences panel could do the same thing – but I have other uses for awaken as well so figured it could do both jobs.

  33. I’ve never actually let my computer go to sleep because I work pretty strange hours and am often logging into it from work and when I’m travelling. Maybe it’s time to revisit this decision though! Thanks again for all the help, Doug

  34. I’m just getting into this laptop, TM at work and home thing. Thanks for documenting all the work you did.

    However, while this all works for my work system, my home system has several issues. First, since it still runs Tiger, no Time Machine. Second, I have both Mac and Windows machines, and I also have several Parallels XP bubbles. These latter have made it impossible for me to use an rsync solution because every so often rsync will self-cancel an operation because it encounters file(s) with ‘special permissions’. Finder also alerts on that, but lets me continue with copying the rest and skipping the ‘special’ files. BUT neither of them tell me which files are marked as Special, nor have I found out yet how to either tell rsync and finder to copy anyway, or how to make them unspecial, or what would break if I did that. Most confusing. I also have not found out what permissions bit is ‘special’ in the chmod documentation. Or what the chmod is for changing the occasional trailing ‘@’ on permissions, or what that means either. Is it the same as ‘special’? I have found that the special flag has something to do with files that get looked at by both Windows and OS X, and that reside in the OS X file system.

    One more rsync question: I have several thousand photos. I like to keep them double-backed up on two external drives (and since I just lost one, it’s just as well) so I do not have to keep them all on the working system. But rsync complains on every file, one file at a time, about some meaningless difference probably related to the fact that I use FAT32 on the backup drives so I can read them on both OS’s. Is there a way to tell it either to bulk OK them or to ignore the difference? I could try again next week if more details on its complaint would help. Meanwhile I have to manually copy folders.

    Thanks again.


  35. Hi Dave,

    I’m certainly no expert, but I’m curious what options you’re using for rsync. If you use -a (for archive) it should copy any special files. The @ sign at the end of the permissions means the file has “extended attributes”. That’s not the same as being a special fileI wouldn’t have guessed they would screw up rsync, but they might. The -E option will copy this info; see this post in Apple’s discussion forum for a bit more info:

    I don’t know what’s going on with your last question; perhaps if -a or -E don’t fix it you could post exactly what options you’re using and what the error message is?

    Good luck!


  36. rsync is very, very dangerous on OS X, though has been improved a lot in more recent versions by the addition of the -E flag that Doug mentioned. If you don’t specify -E rsync will corrupt files by failing to copy the resource fork over. Most files on your system these days won’t have a resource fork, but some will and you won’t want to lose them.

    Google points me to:

    which seems to cover all the details, including making the backup bootable quite well.

  37. Thanks guys. rsync, or rsyncX, still does not quite do it for me, also hangs. I confess a little dubiousness about the seemingly universal technique these sync programs have of first building a list of all the files to be copied. Yes, knowing if there is room on the destination drives can sometimes be useful, but with these 10^11 sized drives I suspect problems running out of RAM or other memory (mis)management issues. Coupled with a failure to properly indicate what files have problems.

    So I think I’m going to write my own Perl script for my specific needs. Just write a log of failed file pathnames so I can post-mortem fix things. All I care about is last modification date and size. Permissions are irrelevant. Going to a FAT32 drive anyway. Can also omit the ._* temps and _* thumbnails and DS_Stores. My only unknown is dealing with resource forks, and so far I believe all the stuff I need to archive is pure data files with no resource fork. Certainly my ongoing stuff is that way.

    A little utility for listing files with resource forks might be nice too.

    So thanks again. I’ll report back when I get my scripts going.

  38. I have a 2ndary backup that I keep in a fire-safe in my garage. The only things I have to worry about are tornado’s and getting robbed. But if my house goes up in flames, my family photos and videos aren’t lost. I do wonder why I haven’t read of others doing the same.

  39. I don’t know why either, Ryan. It’s pretty easy to achieve in any number of ways and it’s amazing how much less stress I have about losing data with a secondary backup that is well protected.

  40. I seem to be having a small issue with setting up two TM drives for my system. I have an Internal 750GB drive that I’ve been using TM on for some time now, no problems. I just purchased an External 1TB that I would like to keep at home then bring in every Friday to do a weekly back up.

    Well anyways, I set up the External Drive, everything went great, however after the initial backup I removed the External Drive and when I tried to reconnect my original Internal drive to TimeMachine I get an error stating that I do not have the proper permissions to write to file “.0017f2036cef” on my TM Drive. Then if I try to change the permissions in finder I get an error stating that permissions can not be changed for that file…

    So basically after setting up the second TM drive, Time Machine will no longer let me use my original TM drive. Any suggestions?

    1. I would suggest looking at the console app (in utilities) after you get the error – it tends to have plenty of gory detail you can use to search in google and get help.

      And yeah, changing permissions on the Time Machine drive never seems to work even as the super user.

  41. TM and redundancy.

    I have a macbook pro laptop.
    I have TM set up to an external FW X_750 HD.
    (works fine)
    I bought a second external X_1T HD, hoping to have an extra measure of safety…to have TM back up to both these drives on a regular basis.

    is that insane, or can that work?

    Can I target both of these HD’s as my time machine backup…while they’re all connected together? to have a backup of my back up?

    1. You can’t backup two drives at the same time, nor can you backup the TM drive to somewhere else (at least not easily, and it’s not worth trying).

      I really think a rotating backup is the best strategy – if you have two backup drives swap them regularly and keep the one you aren’t using in a safe place (preferably not in the same house ;))

  42. I have what is probably a dumb question:
    Can I have two different TM backups?

    I use an external LaCie HD for my MacBook…but of course, I don’t have it plugged in at all times.

    I recently had MS Word crash – and lost a bunch of work. To avoid this kind of frustration, could I partition my internal HD and create a TM file of just My Documents?

    Then of course, I would run the weekly (full scan) TM onto the LaCie.


    1. Nope, you can only have one.

      You can however use Carbon Copy Cloner or SuperDuper! to regularly backup your documents into a disk image – although they aren’t as invisible as Time Machine. On the upside, there’s no need to partition your main drive πŸ˜‰

      A disk image can be stored anywhere, but keep in mind TM will backup the disk image every time it changes. That’s pretty pointless since you’re already backing up the documents with TM, so I recommend excluding it from the TM backups.

  43. Hi and thanks for the great article.

    I have a small drive in my Imac, so I use an external drive as my main disk.

    I have two additional external drives that I manually back up to by dragging the files from the “main” external drive to the two backup drives.

    Can I use time machine to backup to an external drive from another external drive or does it have to be from the drive within my Imac?

    1. Time Machine excludes external drives by default, but if you click on the options button you can remove them from the exclusion list and then they’ll be backed up just like your main drive πŸ™‚

      The only caveat is that the drive must be HFS (mac) formatted in order for TM to back it up – the drive will be disabled in the options dialog if it is FAT32 (windows) format.

  44. Ok this was a very long page full of some interesting comments and advice but I’m still quite confused about my personal situation. Here is the deal: I am using time machine to back up my MacBook Pro onto a time capsule and have been using it for months and it worked great. However, I have important school work that needs to be backed up on more than one drive (a thesis, wouldnt want to watch four years disappear…). So, I purchased a second external hard drive that was not MAC, and obviously not a time capsule. Not knowing any better I backed up onto the new hard drive..but now it refuses to back up to the original time capsule I started with properly…is there any way I can make both of these drives back up at different times without reformatting and using RAID format or something to that extent?

    I hope someone can help! Thanks..

  45. You should be able to switch between Time Capsule and a second drive just like I’ve been doing for the last 18 months. Sounds like something is wrong with the Time Capsule connection, which I can’t help with myself as I don’t have one.

    Have you installed all of the latest patches from Software Update? I think there was a firmware update for Time Capsule recently.

  46. Been a while, but I have my procedures tamed:

    1: Two Time Machine drives, one at work and one at home. I have to open TM Preferences and select the local drive when I change locations, but otherwise it works fine. I do not know why the TM programmer(s) do not look at any drive name “Time Machine Backups” and select it if it contains a backup of their host machine.

    2: SuperDuper daily for instant crash continuation.

    3: I finally wrote that Perl script for merging a local directory tree contents onto a NAS drive. Very handy, no RAM issues, logs failures, not bothered by subtle file permissions (such as 666@). And quite fast too. The first time it copied almost everything again, probably because mod date from previous attempts were not quite synced. Now have 16G free again on my PB for actual work, instead of constantly fighting the “Your hard drive is almost full” notifications.

    Thanks for your comments.

  47. Ok guys and gals. I had the same problem as many have had. I was using Time Machine to do my backups and it ran out of room. I was backing up my 1TB external and 320GB internal to the same second 1TB external. So 1.32TB > 1TB, make sense? So this is what I did. I created a Concatenated Disk Set in Disk Utility. You first add the drive with the Time Machine back up on it (It will NOT deleted or alter the data on the FIRST disk i.e. TM backup). Then you add the second drive to the set. The second drive WILL BE formatted but the first drive WILL NOT be formatted. Read that twice, important. A pop-up should let you know that nothing will be formatted or that it will be formatted. I added a 500GB drive to my 1TB drive and now I have a Concatenated 1.5GB backup drive, and it’s working perfect. Basically it turns two drives into one big drive. I hope this helps. Thanks

  48. I have an iMac with a 1TB internal hard drive and use a 1TB Seagate external hard drive for my Time Machine backups. I’m only using about 300GB of the internal hard drive. I’m paranoid about losing my photos so I have a Seagate 500GB external hard drive that I’ve tried using as a second drive for a Time Machine backup about once a month. When I plug it in, it thinks it needs to do a complete backup rather than just backing up files that have changed. So instead of just backing up the changes, it wants to backup the entire 300GB again and so there isn’t enough room. The Apple phone tech guy said that I couldn’t use two different drives for TM backups but this forum seems to think otherwise. Why does my second drive keep thinking that I am doing a first-time backup instead of replacing just what’s changed?

    1. Cheryl, Sorry for not responding to this. In case you ever check this for a response, my answer:

      If you have both TM drives connected at the same time, it will likely try to back up one to the other (external drives are included in Time Machine by default). You can exclude external drives from the backup procedure, but this might be overwritten when you select it as the backup target.

      I only ever have one TM drive connected at a time and have no issues with multiple drives πŸ™‚

  49. I have just changed the external HDD that I am using as a backup.

    I now want to use my original external HDD for all my music / videos / photo’s etc – and the new one just for backup files (using Time Machine on my MacBook Pro).

    My only issue is that to clear space – I want to delete the old backup on my original HDD. I can see a file named: MacBook Pro_00254bca0c7c.sparsebundle. Am I ok to simply delete this – or am I risking losing something important?

    Sorry for the long winded query – but I have been searching for an answer for quite some time.

    Thank you for your help in advance.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.