Does Time Machine backup external drives?


I have a question for anyone who has upgraded to Leopard, is using Time Machine, and has more than one external drive attached. Does Time Machine backup your other external drives, or just your internal drive?

Example: Let’s say you have an iMac with an external drive (A) attached containing all of your active files. You then attach another drive (B) to use as your Time Machine backup drive. Is Time Machine pulling files from Drive A?

I can’t seem to find the answer to this anywhere. One of the guys at the Apple store thought that TM only pulled from your internal drive, but he wasn’t sure. If this is true, than Time Machine just became totally unusable for me. All of my files are located on externals, including my iTunes and iPhoto libraries.

If anyone can shed some light on this it would be greatly appreciated.

UPDATE: Thanks to the comments by bernd and Dave, it looks like the answer is yes… Time Machine will pull from other external drives. I’m glad the Apple store guy was wrong. :)

UPDATE #2: According to this comment over at The Apple Blog, non Time Machine external drives are automatically put into the exclude list. If you want your external to be backed up, you need to open Time Machine and remove it from the list.

93 thoughts on “Does Time Machine backup external drives?”

  1. I have the same setup, 2 external drives, one for Time Machine, the other for iPhoto. Time Machine is backing up for me from the internal drive on my lowly iMac G5 original, and from the external drive that was not allocated to Time Machine. So the short answer is, it does what you want. The only thing it won’t do is backup data on the Time Machine drive to itself.

  2. I still can’t seem to get this to work. My Time Machine settings panel is not allowing me to exclude my second drive. This is a brand new MyBook drive (factory-formatted in Fat32); could the formatting type be the reason…?

  3. Thanks, Paul. Problem solved. It appears that one needs to reformat his or her second drive in MacOS Extended (Journaled) format before Time Machine can work with it. Most external drives ship using FAT32 formatting, a protocol ensuring both Mac and PC compatibility. Out of the box, these drives are ignored entirely by Time Machine.

    I’m really quite surprised that this seems to be such an obscure topic. Your posted question was one of the only things I could find on the subject. One would think that more people would be tripped-up by this.

  4. Glad to help, KL. I was actually coming back here to comment about this again. I scoured the Apple discussion boards and found the same answer. TM will ignore both FAT32 and NTFS. It will only read-form and write-to HFS+.

    I was surprised too that there aren’t more people talking about this. I’ve had a hard time finding information.

  5. By motherduce on Oct 30, 2007
    But it won’t pull from a networked drive, right? For instance, I want my iTunes on my ABS to be backed up – I’ll have to do this manually, correct?

    This is the question that I’d like answered as well. I’m looking at an nfs mounted UFS-formatted home directory that is greyed out in Finder and Time Machine. I can select it to exclude it, but when I change a file in my home directory through Finder, Time Machine complains that the nfs mount is too big to backup.

    This probably means that only HFS+ partitions are supported, because TM uses Apple’s /dev/fsevents. I really wish that Leopard had moved to ZFS and dropped HFS.

    Isaac Vetter

  6. I tried what was mentioned where I reformatted an external drive as MAC OS Extended (journaled) and it still wont allow me to include it in my Time Machine backups. In the ‘exclude’ window it remains greyed out no matter what I try.

  7. Really lame question, but how do you open time machine. When I try it zooms into the sky screen with only choices being restore or cancel. I just want to open the application. If it saved external HD data will you see the drive (icon) data when you click on the most recent file?

  8. Anne Marie, The “sky screen” is the application. There’s nothing else to see. Simply select the file / folder that you want to restore, and click the “restore” button. Yes, the external HD will be visible in Time Machine.

    See this video for an overview.

  9. I have been able to get Time Machine to backup my external drive just fine, but I have noticed tonight that if I go into the Time Machine application to look at the backups, I do not see the backup of my external drive unless it is plugged in.

    At first I thought perhaps it’s not actually backing it up and what I saw in Time Machine was the actual drive, not a backup, but when I go back in time, the data changes to reflect that it actually was backed up. Furthermore, the data size of the backups reflects both the internal and external drive having been back up.

    So my question is this – what happens if I lose the external hard drive and need to recover the files from Time Machine? How will I do that without the external hard drive? Has anyone had any experience with this? I am thinking perhaps any external hard drive will result in it showing up, but I do not have another one to test it with. Any feedback on this would be greatly appreciated.

    I really need to depend on the backup of my external drive being able to be recovered in the event that something happens to it (being stolen or broken for example), but I am nervous that the backup does not show up in Time Machine unless the actual drive is plugged in.


  10. elisia, you can recover the files without the original external drive attached by simply browsing the contents of your Time Machine drive in the Finder (Not in Time Machine). Double-click on the drive you are backing up to and you’ll see a folder named, “Backups.backupdb”. In that folder will be a folder that has the same name as you computer. In that folder you’ll see a folder called, “Latest”. You can simply drag-and-drop files from the Latest folder to any location on your internal drive or a new external to restore them.

  11. I also think you can recover by plugging in your new (or let’s say a reformat of your original drive), as long as it has the same name. So, just name it the same and it will respond as if it was the old drive — even if the capacity etc. is different.

    I used this approach to get Time Machine to clone a drive…

  12. Recently my boss installed Time Machine on my computer at work. He said it works by taking pictures every hour of what I’m doing and stores the information. Does this mean that whatever I’m doing, even if it’s personal or if I happen to be looking at my online blog say, it’ll record that? I know I sound like an evil employee, I’m really not but sometimes I have to do something else for just a minute at work to clear my mind. Thanks.

  13. Sam, that’s not really what Time Machine does. It makes an hourly backup of your files, but it in no way records what you are doing.

  14. Hi, for the first time today i have used time machine. I also wanted to back up an external firewire and also a usb drive that had my info on it. The comment earlier saying only the internal drive is automatically backed up is the “default” setting. You will notice that in the option settings “of back up”
    your other drives will be visable, These are the drives that will NOT be backed up. If you “DO” want to also back them up: Highlight the each drive and then push the ” – ” button, they will then be taken out of the list of “not backed up drives”…. also I found time machine backed up very slowly and threw an error message when I daisy chained my firewire time machine” drive as the “second” drive in the daisy chain. I then changed the order of the drive and made it the “first in line” this seemed to sort the problem, good luck, Paul

  15. I have two questions about what happens if you have an external drive that’s not always hooked up to your machine when Time Machine runs.

    For example, say you have a MacBook, a big external Firewire drive, and a Time Capsule. You have set up Time Machine to backup the MacBook’s internal drive and the Firewire drive to the Time Capsule over your wireless network.

    You hook everything up and run Time Machine a few times so you have a full backup. Then you unhook the Firewire drive and Time Machine runs a few more incremental backups. Then you hook up the Firewire drive again.

    1) Will Time Machine still recognize that it should include the Firewire drive in your backup? Or will you have to manually remove it from the “exclude” list again?

    2) Will Time Machine continue to incrementally backup the Firewire drive or force a full backup as if the whole thing were new? In other words, is Time Machine smart enough to look back at the last incremental backup of that particular drive? Or does it only check the current file structure against the last incremental backup of the whole system (when the Firewire drive wasn’t connected)?

  16. M, I’m not absolutely positive, but I think Time Machine is smart enough to both, keep the external drive out of the exclude list, and only do incremental backups, even if it’s not always connected. Best way to know for sure is with a little testing. :)

  17. M: Did you ever resolve your question about TM backing up external hard drives that may not always be connected to your computer?

  18. Hi,

    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?

  19. Ian – No, there isn’t a way to do that, because it would pretty much defeat the purpose. The original files and the backup would be on the same drive. If the drive dies, you would lose both. The whole idea behind making a backup is to have the data in two different places, incase one dies.

  20. Ian – that one I’m not sure about. You can definitely use a single partition (of a larger drive) for your backup, but I don’t know if TM will back up the other partitions on that same drive. But again, if that did work… your originals and backup would be on the same drive, so if it dies you would lose everything. Your best solution is to get a second external drive.

  21. hi,
    My situation is slightly different. The TM backup drive is a Time Capsule (drive B in the example above).
    My external drive is connected to this TC over the USB port (drive A).

    Can I use TM to backup my Iphoto library stored on “A” onto the time capsule (B).

    The drive does not show up in “exclude” window. I guess it acts more or less as a NAS.


  22. rene – I could be wrong, but I’m pretty sure TM can’t do that. You’re external drive (drive A) would have to be physically connected to your Mac in order for TM to back it up to the Time Capsule. I think TM works this way to avoid a bunch or redundant backups… For instance, if you had 5 macs on your network that all had your drive A mounted, TM by default would try to back it up from all 5 machines. To avoid this, TM ignores network volumes.

    Do you have the drive connected to your Time Capsule because multiple macs need to access it? If so, you could connect the drive to one of the macs, and then activate file sharing on that mac. The other macs would be able to see it, and TM would back it up from the mac it’s connected to. It’s not as convenient as having the drive attached to the Time Capsule, because that mac would have to be on in order for the others to see the drive, but it may work for you.

  23. Thanks for the feedback. I have “only” 1 Mac(book), so the purpose of connecting to TC is to be able to freely move around and access data everywhere wirelessly, instead of being forced to drag a disk around, or always sit at the desk (=luxury problem)
    I guess I will then need to use Synk or similar to do this for me. No problem on itself: TM to backup the laptop, Synk to backup the library and other external files.

  24. About time machine and external discs: for me it seems that time machine makes a full back up every time I plug my external disc to my computer. I have just made a full back up of both computer and external, then unplugged the external for a couple of hours and now it’s backing up 250 giga information…. exactly the amount of gigas that I have on my external!! damn! seems apple wireless components are really one step from being perfect but still not state of the art!!

  25. I have a slightly different question: will Time Machine backup (to my network-attached Time Capsule) any always-mounted *internal* but non-boot drives inside my Mac Pro? I keep my data on a separate internal drive to obviate permissions issues between different users of this machine.

  26. someone stole my macbook pro this week. i have now bought a new macbook pro and restored successfully from my time machine / capsule. That’s the good news…

    I KNOW that i was backing up my external hard drive – a LaCie 320GB.

    However… bad news, I can’t seem to find any reference to the LaCie on the restore / on the time capusle.

    Can anyone please help (I have nine years of photos on the drive!)? Anyone know how to find the drive’s back up. I saw Ian Teapot’s comment above about buying the same drive and it will respond the same as the previous drive. Does anyone know if this is true?

    Please let me know.

  27. Charlie, That’s such a bummer that your Macbook was stolen.

    I’m a little confused, was your 320GB Lacie drive stolen as well? I’m assuming so since you’re asking about restoring it.

    I’m not sure about the buying of another drive and having Time Machine see it as if it were the original, but you should be able to see the backups on your Time Capsule. Mount your Time Capsule as a drive in the Finder (it should be listed under “SHARED” in the sidebar of every Finder window.) On the mounted drive you’ll see a disc image of your backup, it should be named with the name of your computer, followed by a bunch of numbers, with the extension “sparsebundle”. Double-clicking on the sparsebundle will mount it as a volume. Inside you should see everything that Time Machine has backed up. At the bottom of the list is a folder called, “Latest”. Go into that folder and you should see a folder for your old Lacie (if TM was backing it up).

    Let me know if this works. Good luck!

  28. Hey,
    just restored a new MBP from Time Machine…was flawless.
    I only had to re-enter SN#’s for FCP and ARD.
    I have external drive 1TB that I use for storage, that is not included on my Time Machine hd (400gb)
    Can I do a Time Machine backup for just the external drive, and not include the actual internal drive??

  29. HI

    i have the above setup… but my drive A is a 500GB Buffalo NAS (wireless, on the same network as my Macbook).
    Is it possible to make TM include this in the backup?


  30. I have two external storage drives – one is a 2TB Western Digital and the other is a 1.5TB IoSafe. I wish to run Timemachine on the IoSafe and backup both the IMac and the Western Digital Drive to it. While the IoSafe is formatted for Mac, I can not seem to get Timemachine to now recognize the Western Digital drive to backup. The Western Digital drive up until now has been the drive that I had the Timemachine resident on.

    Let me know if you have thoughts on how to make this all work.


  31. @Chris – Just to be clear, are you saying that when you go into the Time Machine preferences and click on “Options…” that the WD drive is in the list of items NOT to back up… and you can’t remove it from the list? If so, does your WD drive still have a Time Machine backup on it?

  32. Hello – thanks Paul. I have resolved the issue. The WD drive had the TM app running while I was trying to config the IoSafe drive to be the principle TM drive. So once I changed over TM to the IoSafe drive as the principle, it then showed the WD in the exclusion listing (for which I was able to remove.)

    Thanks for everyone’s assistance!


  33. Hi there,

    I am trying to backup my external hard-drive using time machine, onto a second external hard-drive.

    I removed the drive through the Options panel (to not be excluded), it is still attached to the computer, and I left it all running overnight to complete the first backup.

    When I checked it this morning, the only drive that Time Machine has backed up is my internal drive. It hasn’t backed up anything from the other external.

    Any ideas why it is doing this?


  34. @Cathy – Do you know if the external drive you’re trying to backup is formatted in either FAT32 or NTFS? Time machine won’t backup drives with these types of formatting. There’s more information about this in the earlier comments on this post.

    To check your drives formatting:

    1. launch Disk Utility (it’s in your Utilities folder)
    2. select the volume (the drive name) in the left side of the window
    3. the formatting will be displayed in the bottom portion of the window

    If the drive is formatted with FAT32 or NTFS, you’ll have to reformat it in order for Time Machine to back it up. This is an easy task in Disk Utility, but you’ll need another external drive to temporarily copy your files to while you reformat your main drive (formatting will erase the drive).

  35. Ah..damn! That’s the issue…thanks so much for your help. Now, I’m off to move files around for the umpteenth time. I’m sure it’ll all be worth it once it’s done.

    Thanks once again.

  36. hi Paul

    i was very interested in your posts. it s true that apple discussions deoen st mention this problem very extnsively. i have same set-up: mac book, 2 ext HD attached (Maxtor 300 GB, Fujitsu 250 GB) and wireless Time Capsule which is used by Time Machine for back up (2TB). Now with the first HD (Maxtor), i find it in the option list of time machine but i can t exclude it becaue the -button is greyed out. However the other one (Fujitsu) is showing up as well but this one i can exclude by pusing the – button because it s white. I dont really understand why it s different for different HD. Anyway both HD are in FAT32. I read here they should be in Mac ext Jour. I realise i should reformat them and do this by temporarily copy the data onto new HD. Can i use Time capsule for this by manually copy the data into new folder on TC? once the reformat is done i can copy them back from my TC.

    – once the new HD are in Mac ext Journ, can the data still be accessed when plugging the HD into PC using Windows e.g at work i have regular Dell, does this mean i can no longer use the HD there?
    – i have tried to do back up of my laptop with the Fujitsu HD attached and by deleting it from the exclude list in time machine options. it performs a back up but it last only for like 5 sec. this is impossible since the HD contains 170 GB of data which should take at least 10hrs to back up for the first time. also when i check in finder for back ups i see a folder with back up for that time point but it doenst include any data from that ext HD. i tried doing it again by excluding my internal HD of my mac and then the back up folder is actually empty which means it won t back up the ext HD even when i deleted it from the exclude list in time machine options.

    as copy and reformating will take time, is it certain this will work becaue one of the posts above mentioned that even after reformating it to Mac ext journ didn t solve the problem.

    thx for ur help and advice

  37. @Vince – Yes, as long as you have the space available you can temporarily copy your files from the external hard drives to the Time Capsule in order to reformat your drives. You can do this wirelessly, but I would suggest connecting to your Time Capsule via an ethernet cable. the files should copy much faster.

    Unfortunately, formatting the drives as Mac ext Journ will make them inaccessible to your PC. You’ll have to decide which is more important… having your dives backed up with Time Machine, or sharing the drives with PCs.

    Reformatting your drives should work, but there’s always a chance there’s something else going on too. I would do one at a time to see how things go. After reformatting one of the externals, just copy a few files back to it and see if TM can back them up.

  38. which format should it be on the external drive; disk utility is showing a few:

    mac os extended (journal) which is the current format
    mac os extended
    mac os extended (case sensitive, journal)
    mac os extended (case sensitive)


    (I have 2 wd mybooks; a 1tb used as the time machine, and a 250gb used for music/media; which is what i need to be backed up to the 1tb)

  39. “i was very interested in your posts. it s true that apple discussions deoen st mention this problem very extnsively.”

    – I’ve noticed Apple is very quick to delete posts from users having problems with their products. I’ve posted about problems I’ve had in the past and they’ve been removed within a matter of days – with or without a resolution. I’m sure they want to present a problem-free image for their products, but it sure makes it more difficult for resourceful users looking for simple answers to simple questions. Thank goodness for this post here as it just helped me a bunch. Thanks again Apple… for yet again, nothing.

  40. Can I use TM to backup an external drive to another external drive? I have a WD that I want to backup to a LaCie drive – each is 1.8TB.

  41. Lovely long thread. I don’t believe my exact issue has yet been addressed. I’m hoping someone might have some clues for me.

    I want to include a usb WD disk in the time machine backup. It’s formatted as Mac OS Extended (Journaled).

    It is plugged in constantly.

    It does not show up on the list of excluded files, under time machine options.

    I was able to select the disk to add it to the excluded list. And then remove it. Then triggered a backup to see if that might have kick started something. But no joy.

    Any ideas about what I need to do to get time machine to recognize the drive?

    There’s been some mention that some brands are simply unrecognized. Might WD be one of those brands?

    Thank you so much for your help.

  42. Oh! I’m so wrong.

    It has been backing up the external drive all along and I didn’t realize it.

    I guess I was waiting for the piano to drop on my head.


  43. Like many others earlier in this wonderful post, I am trying to backup my external 160GB firewire hard-drive (which has my 50GB iPhoto Library on it) using Time Machine, onto a second external 1TB firewire hard-drive. Both firewire cables are plugged directly into my iMac Intel.

    I removed the 160GB drive through the Time Machine Options panel (to make it not be excluded). It is always attached to the computer. The 160GB drive I want to back up is formatted OS Extended (Journaled). OS 10.6.3.

    Unlike others on this post, this worked at first but it’s no longer working for me!
    –At first the iPhoto library was backed up properly.
    –But for the last 2 days it has refused to update my 160 GB drive anymore. All recent Time Machine backups show the 160GB updated as of 2 days ago, even though the iPhoto Library has been modified often since then.

    Time Machine appears to be unable to complete its job:
    When I watch Time Machine in Preferences while it’s doing a backup, it first says “Backing up: 7.9MB of 148MB”. Then a long pause, then this message is wiped out (still only at 7.9MB) and replaced with “59KB of 140.3MB”. Then a long pause, then “Finishing Backup”. The light on the 160GB drive never flickers during this procedure, suggesting that it is completely missing all the iPhoto backup there (the 140.3MB waiting to be backed up is very probably it).

    Any ideas why it is doing this?

  44. I have connected a new external HD to my Time Machine to store media. Will it back it up automatically along with my computer’s HD or does it have to be connected directly to my computer for it to back-up? I’d prefer not to have the external HD on my desk, but with the Time Machine/Airport to cut down on noise. Thanks.

  45. Here’s my situation:

    Windows Network, with a Desktop PC & USB-attached 1TB Fantom drive shared on the wireless network.

    Macbook Pro on the wireless network (able to file share to/from the Fantom drive).

    WD 1TB USB drive which I will occasionally attach to the Macbook Pro and force a Time Machine backup of the Macbook internal drive, and, hopefully, the Fantom shared drive.

    I have formatted the WD drive to Mac, and I have successfully backed up the internal Macbook drive using Time Machine.

    Is there any way to include a Time Machine Backup of the Fantom drive on the Windows Network? I would prefer to leave the Fantom drive attached to the Windows PC computer.


  46. I have been using an old LaCie 500Gb as my Time Machine Back up, from my MacBook Pro successfully.
    I also have another newer LaCie 500Gb as my iTunes library with over 270Gb of sound on it which I add to gradually. I needed to back up this library an so I bought a third drive. This time a 1Tb laCie. Can I use this 1Tb as my Time Machine back up of the New LaCie iTunes Library and still use the Old LaCie as my MacBook Time Machine backup.
    What I think I’m asking is can I make Time Machine do 2 separate backups.
    MacBook —> Old 500Gb LaCie
    New LaCie 500Gb —> 1TB LaCie
    Without it all going horribly wrong.
    I don’t think anyone on this long thread has asked this question before. Apologies if I’m wrong.


  47. @ AJC – As far as I know Time Machine can only backup to one drive. You would either have to back everything up to your new 1TB drive, or use a separate solution for your second external (iTunes) drive.

    You would lose your original backup drive, but TM can backup your internal and iTunes drive to your new 1TB.

  48. Thanks paul.

    That’s exactly what I suspected & needed to know. Will I have to clear down my 1Tb totally before I begin do you think?


  49. Addressing the comment by M.

    After the initial full backup of all attached drives, TM will perform incremental backups of internal and external drives until a snapshot occurs with one of the external drives absent. Once the missing external is reattached, TM initiates a full backup of all attached drives. Very inconvenient, especially, since journaled file systems have all the info necessary to better reconcile the situation. Hopefully, Apple addresses this in future releases.

  50. I had an external hard drive with loads of work saved on it. Great until I dropped it and now it can’t be recognised no matter what I plug it into. I thought I was safe in the knowledge that my time capsule would have backed up files from my external HD. I had made sure that it wasn’t on the exclusion list when I set up Time Machine. But I can’t seem to find any files on my back up disk. Having done some research online I’m left with the impression that my external HD needs to be plugged in so that the TM knows what backup files it is looking for. Does that sound right? Of course, my problem is my broken HD. Urggh. Can anyone help?

  51. @Jacqui – It should be possible to restore files even though the original drive is no longer connected. Apple provides instructions, here. Scroll down near the bottom of the page to the section entitled, “Restoring data from an unavailable disk (when multiple disks are used)”. (Click on the section title to expand the instructions)

    Also, before you toss your external, you should determine if it’s the drive or just the enclosure that broke. You can pick up a cheap enclosure for about $15 and move the drive into it. Hopefully, it’s just the enclosure that broke and the drive is OK.

    If all else fails, you can manually restore the files by mounting the backup volume. In the sidebar of a Finder window, click on your Time Capsule to mount it. You backup file should be named [computer-name].sparsebundle. Double-clicking that file will mount your backup as if it were a drive. You should then be able to simply copy the files via drag-and-drop.

    Good Luck!

  52. Paul
    I have the same problem as Jacqui – the guy at the Apple store said if my External drive was connected when time machine was backing up it should be in the backup – I can’t find it anywhere. I have the drive off to be recovered but would prefer not to pay if I already have it ;-).

    The drives have never been on the exclusion list so should have been backed up but I can’t see them anywhere going back to 2009 – I know I should have checked but you know they say you have to experience this pain to get your system into shape! Is there a way using time machine that I can ensure a backup of an external portable drive to my main backup at home on a regular basis. I am struggling to get an answer – have been to the Apple store but came home to try and no joy. Thanks in advance.

  53. Hi Amanda,

    Did you try the procedure that Apple recommends? I linked to it in the previous reply? While you’re in Time Machine, you should be able to click on your computer name (found at the top of the devices group in your Finder sidebar) and see the (missing) external drive. I don’t think you’ll need to navigate back to any particular point in time. It should just be there (I think).

    Are you backing up to a Time Capsule, or a second external drive?

    You can download the Time Machine Buddy dashboard widget and that may give you some insight into what has been backed up.

  54. Hi Paul
    Thanks for your reply – I did try that but it is not showing up anywhere. I am backing up to an external 1TB WD drive. All of my iMac backup is there but none of the external drives. I am wondering if it was not set up correctly. I have just tried a new portable drive and when I open the Time Machine Preferences it appears that the portable drive is invisible to Time Machine. Do you know how I can ensure that Time Machine will back up the portable drive? Also if this portable drive is not always connected do the new backups delete what has been backed up previously therefore deleting an earlier backup that may include the portable drive?

    Sorry to bombard you with questions. I am trying to come up with a system so that I won’t have this problem again.
    Many Thanks

  55. Hi Amanda,

    Was Time Machine Buddy any help in showing what had previously been backed up?

    Without going into Time Machine, plugin your 1TB WD drive, and open your backup file (through the Finder). Do you see the missing drive listed in there if you just navigate around through the finder? If not, then it looks like the other drive was never backed up. That’s very odd if it’s never been on the excluded list.

    It’s also very odd that TM can’t see your new drive. If you plugin your drive, and then go into the TM system preference, and then click “Select Disk…” – do you see your new drive in that list? If you do see it, and it’s not on the exclude list, TM should back it up. If you don’t see it in the list, then TM probably can’t see it either, but I’m not sure what would cause that. If the drive is empty you could try reformatting it using Disk Utility to see if that helps.

    Unfortunately, TM doesn’t provide a visual method of confirming a drive is being backed up. You either have to check the backup yourself, or use 3rd party software (like Time Machine Buddy). I believe there’s other TM-monitoring software available, but I haven’t used any of them.

    If the drive is being backed up, and it’s not plugged in at the time TM runs, the backup should still be intact. Meaning, the backup shouldn’t be overwritten just because the drive is missing. BUT, if it’s been a long time since the external was last backed up, and TM is running low on space on the backup drive, it will start deleting old backups to make room for new ones. I believe it would still leave the backups for the external alone, and start deleting old backups for your internal instead, but I can’t say that for sure.

    Sorry I’m not being too much help. For future backups, you may want to consider a 2-prong approach. I still use TM for local backups, but I also use Backblaze for remote backups. It works well and it’s only $60 per year. I recommend remote backups because that way your files are safe even if your house burns down.

    There is one important thing to know about Backblaze – it’s not a true archive, it’s a backup – there is a difference. An archive will keep your files in it until you delete them (from the archive). A backup simply mirrors your drive, so if you delete a file from your main drive it will disappear from your backup as well. SInce that’s how Backblaze works, it treats external drives in a similar way. If your external drive isn’t connected for a few weeks, those files will disappear from the online backup. If you use Backblaze to backup an external drive, you have to remember to plug it in from time to time even if you’re not using it.

    I’m also a fan of Drobo. It’s a box that you put multiple drives into and it maintains it’s own redundant copies of files. Its a little pricey, but it works well.

    Good luck!

  56. Hi again Amanda,

    I totally forgot that TM won’t backup drives that are formatted as FAT32 or NTFS. You can read more about that on this comment from 9/04/2009.

    If your old drive was formatted this way, that’s probably why it was never backed up. That’s also probably why TM doesn’t see your new drive, as it’s very common for drives to be formatted as FAT32 right out of the box.

  57. Thanks so much for your responses Paul – that will explain it – I had my drives formatted as FAT32. I am now in the process of saving what I have and putting a new system in place.

  58. Hi Paul,

    I have a Lacie 500 GB ext drive as my Time Machine backup. I also have a Drobo with lots of other files. I recently moved my iTunes and iPhoto libraries to the Drobo. The beauty of the Drobo is that if one of the drives fail, my data will still be protected. But what if something (I am not sure what can happen) happens and I lose the data on the Drobo? My iTunes library is synced with my iPod Classic. That’s fine. But what if I lose my iPhoto library? I have no other backup. What if I could add it to my TM backup? Is there a way to add just a folder from an external drive to TM? I know you can exclude but can you selectively add folders? By the way, at the moment, the whole Drobo is in the TM exclusion list.

    Thanks in advance for your help.


  59. Hi Terry,

    You should be pretty safe with the drobo. As you mentioned, if a drive fails you’re still protected. The only way you would lose your data is if multiple drives failed at once, or something happened to the whole box.

    That being said, I’m all in favor of multiple backups. I don’t know of any way to add individual folders to TM, so the only way to add them would be to:

    1. Remove the drobo from the Exclude list (so it gets backed up)
    2. Add every folder on the drobo (except your photo and music libraries) to the exclude list (so nothing gets backed up except your music and photos)

    You can make this easier by simplifying the file structure on the top level of your drobo. You could move everything into 3 folders – “Music”, “Photos”, “Files”. That way you would only have to add “Files” to the exclude list.

    I’m also a big fan of off-site backups. You can have the best (on-site) backup solution in the world, but it won’t matter if your house burns down. I personally use Backblaze.


  60. Thanks for the advice Paul. I also thought of removing the Drobo from the list and re-adding everything else but the iPhoto library but I was hoping there was a better way. However your idea of rearranging the folders at the top level is great.

    Thanks for the advice and keep up the good work.


  61. Hi Paul,

    First thank you for all the great information you have provided in this thread. I am hoping you can shed some light on the following.

    I have an Airport Extreme that I want to connect a USB hub and my two external drives to it. I would like to set up a new 1.5TB drive to Time Machine back up my 1TB media drive and my MBP 320GB hard drive.

  62. Hi Glen, Unfortunately I’m not going to be much help. I don’t know if you can backup one drive attached to an airport extreme to another drive attached to the same airport extreme. Using Time Machine with an airport extreme has had some controversy surrounding it. See this article for more information. Good luck!

  63. Paul, also want to say thanks in advance for being so helpful to everyone here.

    I have used time machine to back up a fresh system install with all my applications. I plan to only run time machine after before and after software updates (which I’ll do every 2-3 months) or large application installs. I have set “Lacie 1” as the time machine backup disk.

    I also have all my data (documents, files, music, pictures) stored on the same “Lacie1” external drive. I now want to back that drive up (including the time machine backup) to a “Lacie 2” external drive.

    Is there an easy (Carbon Copy Cloner perhaps) way to keep the “Lacie 2” backup updated to remain an exact copy of the “Lacie 1?”
    Also, will the Backups.backupdb folder on my Lacie 2 be recognized by time machine in the case that my Lacie 1 HD fails?

    Any help or advice would be greatly appreciated.

  64. Hi,

    I have been following this thread for a while but haven’t seen a situation like this posted (perhaps I missed it?):

    I have an external drive formatted for the Windows NTFS format.

    I have an iMac that has the latest Paragon NTFS Driver installed in which I can read/write to and from NTFS drives.

    I have Time Machine backup drive that is formatted correctly with the Mac OS Journaled format.

    Since the Paragon NTFS driver is installed, the external NTFS drive can now be taken off the “excluded list” from Time Machine.

    Will Time Machine now be able to backup data that is stored on the external NTFS drive?


  65. Hi every one,
    I get this situation:
    – a Time Machine backup drive
    – an external NTFS formatted drive I want to backup to it

    From the Time Machine settings section, I can see the NTFS drive, remove it and register this change.

    However, when I come back to Settings, it is still there. I can not remove it.
    Meaning that it is always excluded from the procedure, I am not able to backup it.

    I tried to remove and install Paragon NTFS drive, but nothing changes.

    I made several tests, and this situation occurs only with NTFS drive, not HFS+.

    Does someone understand this situation ?
    It there a fixe to it ?

    Thank you,

  66. Hello Paul,
    I would like you to tell me if what I’m thinking to do will permit me to have Time Machine backup my external drive.
    1. I’m going to copy all my files which are in my external drive to another.
    2. I will format both of my drives (external and backup of external) in format MacOS Extended (Journaled) which seems to be the only format which works with ime machine.
    3. I will copy back my files from the external drive to the external drive I want to use as an extension of my computer’s memory.
    4. I will tell time machine to make a backup using the other hard drive (also formated to MacOS Extended (Journaled) )
    5. I enjoy my files are backep up.

    Should this work?? is there any other format I could format my drives so that I can also connect my working hard drive (not back up drive) to a windows operating system and work with it or copy some files.

    thanks and I eagerly wait for your response.

  67. I have the same issue with Paragon NTFS drive installed and external disk with NTFS format. Timemachine won’t save the exclusion list changes.

  68. Hello, I’m here to flog this old thread with a related query that I haven’t seen addressed yet.

    I use TM to backup a large external drive connected to my laptop. The drive backup is included with my laptop’s backup file. So far so good. Now I have a new laptop, replacing the old one. I’m attaching the external drive to the new machine, same as before. Now I want to do a new TM backup of the new machine on the same TM volume as I’ve been using, as there’s still some space.

    Is there any way I can get TM to use/add to the old backup of the external drive, but with the new computer? Does that make sense? It doesn’t seem to make sense to initiate a whole new backup of the external drive on the same volume that already has a backup of it. I suppose I could delete the old backup and start a new one in the new computer’s file, but it would be nice to preserve all that TM incremental history if possible. Thanks for any advice.

  69. Hello,
    I have yet another situation, that I believe is similar to Coxy’s, but here goes if anyone can help out. I have a 1TB internal drive that TM is backing up onto another 2TB internal drive (it is backing up the entire drive). I also have another 2TB external drive that I wish to use as a back-up drive, but ONLY for backing up my iTunes and iPhoto libraries. I intend to partition this external drive into two 1TB drives, one for the two backups, the other as just ‘extra’ space. I don’t believe that TM can do this, but is there another 3rd party app that can? I am guessing that if this external drive were a true apple ‘time capsule’ that this would be possible, so what makes the ‘time capsule’ special that allows it to do this? In other words, is there is program that comes with the time capsule that allows this to work and if so is it available somewhere on the net? Or should I just opt for the 3rd party app. Or am I stuck with just dragging and dropping both the iPhoto and iTunes directories onto the external every once and a while manually? (and would this manual method be sufficient – are the whole ‘iTunes’ and ‘iPhoto’ directories self contained, or are there other files scattered about the Mac that are somehow needed as well, which would make this method unusable as a backup?). I appreciate any help in advance!

  70. I have 2 external drives connected to my mac, both formatted to MAC os journaled. One of the drives contains only my itunes library, and I want the other to be my backup for everything, inlcuding that drive. If I unplug the itunes drive, time machine backs up no problem to the external, but when I plug in the itunes drive, I get an error from time machine, implying that their may be something wrong with my back up disk. Any suggestions?

  71. Great thread guys, thank you so much for all the information. I wanted to mentioned that, at least in OS X Lion, you will get no indication TM is backing up an external drive. In other words, if your external is being backed up, you would not even know, as TM preferences only show the drives being “excluded.” I found that entering TM will show your external drive (if backed up) on the side bar. Additionally, I used a solution previously mentioned here to verify my external was being backed up:

    “On the mounted drive you’ll see a disc image of your backup, it should be named with the name of your computer, followed by a bunch of numbers, with the extension “sparsebundle”. Double-clicking on the sparsebundle will mount it as a volume. Inside you should see everything that Time Machine has backed up. At the bottom of the list is a folder called, “Latest”. Go into that folder and you should see a folder for your old Lacie (if TM was backing it up).”

  72. Awesome thread. I wanted to add that this works with thunderbolt drives (Lacie in my case) as well. I had included thunderbolt in my websearch and didn’t find this article at first, and I really wish I had since it answered all my questions. Hopefully my adding thunderbolt a couple times will help out the next guy like me.

  73. Thanks for providing some extremely useful information, Paul.

    I’m currently backing up 150 +/- gigs of iPhoto libraries attached to two separate users on our iMac. Thanks!

  74. Paul and others – thanks for the informative discussion. One clarification that would help me. I get that we need to format the external drive from FAT32 to Mac OS Extended (journaled) for time machine/capsule to include and back-up the external drive. I recently bought a G Drive Mini portable drive from the Apple Store that claims to be formatted for Mac (HFS+). The guy at the store couldn’t tell me whether HFS+ was sufficient or that I need to reformat it for Mac OS Extended (Journaled) or whether they are the same. I am not in any way tech minded, so would appreciate guidance on what to do and whether HFS+ is same/different from Mac OS Extended Journaled. For reference, I have a MacBook Pro with the latest operating system.

  75. Paul,
    I wanted to thank you for your simple direct answers. I use my computer a lot but am not an expert. I had two challenges with backing up my external hard drive using Time Machine and your suggestions worked perfectly. That is very refreshing.

  76. Paul – thanks for sharing a great article that answered my question. My 2 external HD’s were originally connected via my Airport Extreme and when I went into Time Capsule to select/remove the 1st external HD wasn’t visible. Once I connected them directly to my Mac, both were visible and I was able to do what you said. Thanks again.

  77. Hello whoever is still reading this thread. I have an annoying problem: I have a USB stick that I want TM to backup to my external hard drive. TM works fine backing up my internal harddrive.
    I have formatted it HFS+ and put a few iPhoto libraries on it.
    When I open TM preferences, the USB stick is in the list of excluded volumes. I can select it, click ‘-‘ and it goes away. But if I click ‘Save’ and then ‘Options’ again, the USB stick shows up in the list of again!
    Obviously it does not get backed up to the external harddisk.
    I have no idea what else to try.
    This is on and MBP running 10.8.3.

  78. Paul,

    Wondering if you can help me – I am trying to back up one hard drive to another hard drive as the original post mentions. I’ve removed the one I want backed up from excludes list etc. Th part I am not understanding is when I run back up, will time machine back up both my internal hard drive and the external hard drive onto my new hard drive? I am not trying to back up my internal hard drive twice as it is already on the external drive I am trying to back up.

  79. Hi!

    I’m trying to get my Western Digital “My Passport” (for Mac) to only and only backup my other external hard-drive.

    However, when I try uncheck the hard-drive that I want to copy, I cannot erase from the list of excluded hard-drives in the Time Machine settings. That is, the name is faded grey and I cannot remove it from the list. Any ideas why?

    Is it a problem that the hard-drive that I want to copy is MS-DOS (FAT32) and the hard-drive with Time Machine is Mac OS Extended (Journal)????


    // Erik

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