Mac Productivity

How to Partition Your External Time Machine Hard Drive

Dan Helyer Updated 23-03-2020

Now that almost every Mac ships with a speedy solid-state drive, many of us have learned to live with smaller storage capacities in our computers. At the same time, external hard drives are cheaper than ever. That means it’s easy to get yourself an external drive big enough to partition for both Time Machine backups and external storage.


If you plan to use a drive for both of these purposes, there are a couple of points you need to know first. We’ve explained everything below, including how to store files on your Time Machine hard drive without even partitioning it first.

How Time Machine Works

Time Machine showing historical backups of Home folder

Time Machine works by creating historic backups of your Mac. This means it keeps older copies of files even after you edit or delete them, until a time when you need more storage for newer backups. Thanks to these historic backups, you can travel back in time to restore your Mac’s data 3 Ways to Restore Data From Time Machine Backups Here are several methods for how to restore your Mac using Time Machine, including what to do about "searching for time machine backups." Read More from days, weeks, or months ago.

In contrast, the alternative to historic backups is to overwrite the previous files every time you back up your Mac. With this method, you’d have no way to retrieve a deleted file if you already made a new backup. Obviously, that isn’t particularly useful.

The downside to Time Machine’s historic backups is that the oldest files remain on your drive until it runs out of storage. You might not care to have extensive backups of files you deleted years ago, in which case there are better uses for your external drive.


Be Careful When Storing Files on Your Time Machine Drive

The more you use a mechanical item, the more likely it is to fail. Your external hard drive is no exception; it has moving parts that read and write data, which can give out over time.

If you choose to use your Time Machine drive as external storage, you might shorten its lifespan by doing so. This is because the drive will carry out many more read and write actions as you save, edit, and delete extra files.

Copying files to Time Machine drive progress bar

It’s also worth mentioning that Time Machine doesn’t back up any extra files you keep on your external drive. Even if it did, you’d lose the original files and the backup at the same time if your drive stopped working.


We strongly suggest you keep multiple backups in different places for any important data.

Store Files on Your Time Machine Drive Without a Partition

Time Machine drive being used for file storage in Finder

Technically, there’s no need to partition your hard drive if you want to use it for external storage as well as Time Machine backups. All you need to do is start copying files and folders onto the drive using Finder.

If your Time Machine backups are encrypted, you might need to authenticate changes to the drive with your administrator password.


Just make sure you don’t edit or save anything to the Backups.Backupdb folder. This is where Time Machine stores all its backups.

As your external drive runs out of storage, Time Machine deletes the oldest files from the Backups.Backupdb folder to make space for new ones. If your files are in that folder, Time Machine might delete them as well.

You might want to create a new folder, called Files, to clearly separate your files from your Time Machine backups.

Time Machine drive with separate Files folder


The Pros and Cons of Avoiding a Partition

The above method is the quickest and easiest way to save files on your external Time Machine drive. Unlike using a partition, which we’ll explain below, you can start saving files to the drive without erasing all your existing Time Machine backups first.

But the lack of a partition also means your Time Machine backups will continue to swell in size until they take up all the free space on your external drive. Although Time Machine won’t delete your personal files when this happens, it might take up more space than you want it to.

That’s why a partition is the most practical long-term solution. You can allocate a set amount of space for your Time Machine backups and for your file storage so neither one hogs the available storage.

Create a Partition to Store Files on Your Time Machine Drive

Disk Utility showing Time Machine drive with partition

After you partition a hard drive, your Mac sees each partition as a separate drive. They have distinct names, varying amounts of storage, and can use different formats. You even need to eject each partition separately before you can safely unplug your drive.

Unfortunately, creating a new partition often erases your external drive. That means you may lose any existing Time Machine backups. You can make a Time Machine backup after partitioning the drive, but your backup history will restart from that point forward.

When you partition your hard drive The Pros and Cons of Partitioning a Hard Drive: What You Need to Know Wondering whether you should partition your hard drive? We take a look at several reasons for and against partitioning today. Read More , you get to choose how much space to allocate for your Time Machine backups. We recommend that you allow two to four times the size of your Mac’s internal drive. If you don’t want years’ worth of backups, you can reduce this size as you see fit. However, you shouldn’t go smaller than double the size of your Mac.

For example, if you have a 128GB MacBook, you should allocate at least 256GB for Time Machine backups. If you can spare more space, definitely do so.

How to Partition Your External Drive

  1. Connect your external hard drive to your Mac. Then go to Applications > Utilities and launch Disk Utility.
    1. If you can’t find it, press Cmd + Space to search for Disk Utility using Spotlight.
  2. Select your external drive from the sidebar and click the Partition button. Use the Add (+) option to create a new partition and choose the Name, Format, and Size for each partition by selecting it in the diagram.Partition options from Disk Utility in macOS
  3. Your Time Machine partition must use the Mac OS Extended (Journaled) format, but your file storage partition can use any format. Choose ExFat if you plan to use it with Windows; otherwise choose Mac OS Extended (Journaled).
  4. When you’re ready to create your partition, click Apply, followed by Partition. When the process completes, you should see each partition as a separate drive in Finder.Partition confirmation popup in Disk Utility
  5. If you can’t partition your external drive, you may need to reformat it first. Select your drive in the sidebar and click the Erase button. Choose any name and select the Mac OS Extended (Journaled) format. After erasing the drive, return to step two above.Disk Utility erase window

After partitioning your drive, you need to set up Time Machine How to Use Time Machine to Back Up Your Mac Time Machine is your Mac's built-in utility for backing up your computer. We'll show you how to set up Time Machine, make backups, and more. Read More again. To do this, open the Apple menu and go to System Preferences > Time Machine. Click Select Disk and choose your new Time Machine partition to start creating a backup.

Remember that your Time Machine backups will start from scratch from this date forward. Also, don’t forget that you need to create separate backups for anything in your file storage partition.

Better Use for Your Mac Storage

If you don’t need access to five years’ worth of backups—and you’re careful about keeping your most precious data safe—you probably don’t need too much space for Time Machine. By partitioning your drive, it’s easy to create a separate space for Time Machine backups alongside other media or files you want to store.

If you find you’re still running short on storage, you’ll be glad to know that external hard drives are cheaper than ever. Take a look at the best external drives for a Mac The Best External Hard Drives for a Mac Need more storage? Check out the best external hard drives for Mac to add more space easily. Read More to find out what options are available.

Related topics: Data Backup, Disk Partition, File System, Hard Drive, Mac Tips, Mac Tricks, Time Machine.

Affiliate Disclosure: By buying the products we recommend, you help keep the site alive. Read more.

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  1. Juan Manuel
    January 27, 2018 at 10:16 pm

    Do you know what hard-drive brands are compatible with partitioning in mac? I have an iomega and works perfectly with a time machine partition and a second for storage. However, I just had to return a seagate because I could not partition it.

  2. Manuel
    January 27, 2018 at 10:13 pm

    Do you know what hard-drive brands are compatible with this? I have an iomega and works perfectly with partitioning but it did not work with a seagate. Thanks.

  3. William Totman
    November 22, 2017 at 4:34 pm

    Time Machine, at least in High Sierra, does not require a dedicated partition to create and maintain backups.

    When you add the non-dedicated drive, it will ask if you wish to stop using any previous Time Machine disks or to use "Both". If you select "Both" Time Machine says it will alternate between the drives you have made available to Time Machine.

    As with a dedicated partition, Time Machine will create a "Backups.backupdb" in the root directory of the newly added drive - right next to any other directories or files already on the drive.

  4. luciano.x
    March 9, 2017 at 12:47 pm

    This is helpful. Thanks.
    I had a small issue. My 500GB HD was already partitioned (GUID Partition Table) but for some unknown reason Disk Utility could not erase (format).
    I just deleted all partitions in another utility (GParted on Linux) and back to Disk Utility created the partition scheme as I wanted:
    1 HFS+ (Time Machine)
    2 Free space (to use later as Linux filesystem)
    3 Free space (to use later as Windows filesystem)
    Everything worked great.

    PS: Disk Utility created as well one EFI System Partition (ESP) 200MB so there is 4 slices.

  5. Kat Patrick
    January 24, 2017 at 9:19 pm

    Hey ya, Tim. This is just the step-by-step process that I want to store stuff from my itty-bitty Mac HD while keeping the Time Machine back-up. Partitioning is definitely the answer. I have a 2 TD My Passport for Mac, but it's not working either on Erasing (step 2) or by going directly to Partition. It says it can't open the device, so I haven't been able to proceed any further.

    • Tim Brookes
      January 25, 2017 at 2:56 am

      Sounds like there could be a problem with the drive itself. Is it currently working as a regular Time Machine or other disk? Is it new?

      • Kat Patrick
        January 25, 2017 at 4:25 am

        It seems to be backing up as a Time Machine device just fine, even making a new back-up today. I've had it since September last year.

        • Tim Brookes
          February 21, 2017 at 3:01 am

          So have you managed to partition the drive at all? Is it just one partition that won't work?

  6. joan
    January 5, 2017 at 7:25 pm

    Not being tech savvy and being a senior citizen, I found this very easy to follow. I had originally not partitioned the EHD but after running Time Machine for a few days, I decided to erase the 4TB EHD and divide it into 2 partitions. So far it is working and presently loading up Time Machine again. Thanks for your very clear and easy to understand instructions.

  7. Luis Antunes
    December 10, 2016 at 4:17 pm

    Thanks Tim for a very clear explanation.

    I have been struggling with partitioning my TimeCapsule (2TB), since I was already using it for TimeMachine only.

    I seem to find several problems:

    -A- I now have a 250GB SSD, I want point TimeMachine to the TimeCapsule (to a partition, say TCPart1).
    -B- I have to keep my Photos Library in an external hard drive (say HD1TB). So I want to manually copy (an 8-hour operation) my 130GB PhotosLibrary from the HD1TB to a TimeCapsule partition (say TCPart2).
    -C- My son bought a new mac, and he would like to point his TimeMachine to the TimeCapsule. Do I need to create a TCPart3, or can he point to TCPart1?

    Several related subproblems:
    -- occasionally, the TC disappears from the DiskUtility list of visible disks. Is this normal?
    -- I have just re-formatted the TimeCapsule and started 2 new partitions. However, when I go to TimeMachine "SelectBackupDisk" I can see (and choose) only the TimeCapsule on the whole, whereas I would like to choose the appropriate partition, but it's just not there. This happens in my son's mac too.

    Sorry for all the trouble, this whole thing should really be much easier than it is. Thanks for your attention.

  8. Christine McKay
    November 5, 2016 at 10:02 am

    I'm not knowledgeable about computers. Often I look for help and it is not helpful. I was able to follow your instruction even though a circle was used to define the partition. Thank you!

  9. Phil Clark
    August 24, 2016 at 3:45 pm

    If I partition a 5 TB drive into two 2tb and one 1tb partition, and use a two TB partition for TimeMachine and the other partitions for documents and Scratch Disk for Photoshop, will Time Machine back up the Documents partition even though it is on the same physical drive as the Time Machine Backup.

    • Dave
      October 17, 2016 at 1:14 am

      Hi, I was just wondering if you got an answer to your question about whether time machine will back up files/media in a partition on the same physical external drive as it is on?

  10. Michelle
    August 18, 2016 at 11:43 pm

    Hi I did this but now when connecting to mac only the time machine appears. How can I access the partition?

    • Tim Brookes
      August 23, 2016 at 3:00 am

      It should just appear. If you open the Disk Utility app and click on your hard drive, do you see two partitions?

      If so, can you select the storage partition? Try clicking on "First Aid" to see if your Mac can fix any issues. Some drives (I have one) tend to do this occasionally, while others work just fine. I find that sometimes unmounting the drive and reconnecting it works, you could also try restarting your Mac.

      Hope that helps, let us know!

  11. Sarah
    May 19, 2016 at 4:17 pm

    Hello -

    I was just wondering if, later on after you've done this and partitioned your drive, if it's safe to change the size of the partitions?



    • Tim Brookes
      May 23, 2016 at 4:47 am

      Hi Sarah,

      That depends on the file systems you have chosen. Time Machine uses a HFS+ (Mac OS Extended) file system, which can be resized on the fly fairly safely based on what I've read. If you're also using an NTFS partition to store data (a Microsoft file system), then I would probably recommend backing everything up before you try resizing. NTFS can be resized, but I've heard many stories of lost data and corrupt partitions when doing so.

      If you are using FAT32 or FAT16 then I would have to say no, based on what I remember from my Windows 98 days.

      If you have two HFS+ partitions then it seems like a fairly safe procedure. As always, I'd recommend having a few backups though, especially if the data is really important (irreplaceable photos, work etc).

      • Sarah
        May 23, 2016 at 7:58 pm

        Thank you Tim!

  12. Emma
    December 21, 2015 at 4:19 am

    Will files now automatically go to the free space on my external hard drive when there is no more space on my computer? Because I have stopped receiving iMessages on my computer because of lack of space and would like to start getting them again.

  13. Josh
    November 30, 2015 at 10:03 am

    Hi Tim, just a quick question,

    How did you manage to format the "Sagat" (Street Fighter?) partition to NTFS in disk utility? I'm on El Capitan now, and i'm not sure that format is an available option.


    Josh R

  14. Michael Andrews
    June 3, 2015 at 8:21 am

    Tim, When I try to select a backup disc, Time machine will only show the smaller of the two partitions as an option for the backup location. I wish to use the larger of the two partitions for the time machine backup, and the smaller for file storage and transfers. Is this possible? And if so, How? Thanks, -Mike

  15. Vanessa Yvonne
    May 26, 2015 at 5:57 pm

    Hello! I've been using my TC as an external hard drive since 2009 but since I've recently updated my Macbook, I can't figure out how to do it! I didn't set up a partition, I would just open the TC file and drag and drop my files there. Now that location doesn't seem to exist. Any ideas of how I can find the file? Thanks!

  16. Jennifer Lyon
    May 19, 2015 at 4:51 am

    I need to back up my MacBook Air so that I can run Parallels, Windows, then download the Xactimate 28 software system-- which only downloads to Windows. I'm thinking I will purchase 1TB external hard drive that doesn't need to be formatted and works with Time Machine. The result is I am hoping is that If I purchase the right one that I can plug in and pretty much run Windows and Xactimate and back up to Time Machine. Am I on the right store or do you think think I'd be better off just going in to an Apple Store??

    Thank you, I really haven't a clue...!

  17. Monica
    March 27, 2015 at 7:40 pm

    I just purchased an external hard drive for my MAC desktop. I want to store all my photographs (currently 889.29 GB) on this external drive. I also would like to store my backups (I've never done one) on this external drive. Is this possible?

    • Tim Brookes
      March 30, 2015 at 1:19 am

      Yes... just follow the instructions in the article above.

      First partition the drive, then copy your data to the storage partition and point Time Machine to the other partition.


  18. AL. S
    March 18, 2015 at 5:45 am

    Hi, Tim, thanks for answering my questions. I got it! I see why my second question is confusing. No problems for now. Thanks again.

  19. AL. S
    March 15, 2015 at 4:06 pm

    Hi, thank you very much for the great solution to use an external hard drive. However, after reading it, I become more puzzled because: (1) I just bought Touro S for moving the ever expanding iPhoto Library and iTune stuff plus other files to save my disk space in Macbook Air. I did the erasing part to get it ready for Mac. But I don't know which filesystem I should choose in partitioning. Any system is Okay? (note: I want to dedicate Touro S to file storage; I am using WD My Passport for Time Machine); (2) Another question related is how I should do with the Time Machine setting to make it continue backing up iPhoto Library and iTune..etc after I move them to Touro S? Does it matter with which filesystem I choose in partitioning Touro S? Thank you.

    • Tim Brookes
      March 16, 2015 at 3:16 am


      1) Which filesystem you use depends on which other operating systems you intend to use your (storage) drive with. Mac OS Journaled is great for use with Macs, but exFAT is better for cross-compatibility with Windows and Linux.

      2) I'm not entirely sure I understand your second question. Your Time Machine backup will only backup to your Time Machine drive. If you partition a larger drive, the only partition you need to worry about is the one you want to store stuff on (see my answer above). The second partition (the one you intend to use to backup with Time Machine) will be configured by your Mac.

      Feel free to get back to me with more info, I will try and help out in any way I can.

  20. Anonymous
    March 3, 2015 at 8:15 pm

    Hi, great article. If you've already used the external drive to hold files, is it too late to partition it? Would I have to move the files somewhere first, the partition it, then move the files back?

    • Tim Brookes
      March 3, 2015 at 11:18 pm

      It really depends on the filesystem used (NTFS, FAT32, exFAT etc). Some filesystems don't complain too much when you resize them, others completely lose the plot and data can be lost in an instant. Regardless – there is only one safe way to do this, and it's exactly what you described – move the data elsewhere, partition the drive as you would like, then move it back.

  21. Kirk
    February 27, 2015 at 4:23 pm

    Thanks Tim for the clarification. The last bit was the part that was tripping me up, because I'd figured on there being more of a white list approach, rather than a black list one for drives to back up. The latter seems easier to set up, but I guess Apple being Apple, it's more foolproof for users if out of the box Time Machine backs up any drive it sees.

    Thanks again — now just have to watch what USB sticks I leave in the machine or plug every one I have in to add it to the black list :)

  22. Kirk
    February 26, 2015 at 10:26 pm

    Any idea how to keep Time Machine from backing up every drive that's ever connected to the Mac? I have some pocket external drives that I use for travel and if I connect one to one of my Macs and Time Machine kicks in, TM starts adding that external to it's backup for that Mac — which I don't want.


    • Tim Brookes
      February 27, 2015 at 2:39 am

      Hi Kirk,

      Sure, you can do this under System Preferences > Time Machine > Options... – in this menu simply add the drives that you do not want backed up, and they will be excluded from future backups.

      Naturally, you'll need to connect the drives in order for them to show up so that you can add them to the list.

      Hope this helps!

  23. chad towner
    February 22, 2015 at 11:38 pm

    Once I have partitioned my hard drive for time machine, how to I access the other partition that is not designated for time machine? I want to download and store items on the other 1.8 TB that I have left and also want to make sure I never store anything on my time machine partition. thanks in advance

    • Kirk
      February 26, 2015 at 10:11 pm

      Chad, any partitions on a drive will mount as a separate "drive" on your desktop (if you have your Finder preferences set to show connected drives on desktop) and in your Finder windows' left column under the subhead "Devices" (again here, make sure that your Finder preferences are set to display external drives by going to Finder, then under the Finder menu select Preferences, then under the Sidebar tab check the box next to External Devices that's under the Devices subhead.

  24. Anil Akbulut
    February 20, 2015 at 11:44 am

    Hi guys thank you for this article

    I have one external driver which is 1tb. After partition I do have 400gb for time machine and 600gb for Storage.

    But I had a problem. When the Time Machine backups, it gets 60gb from my macbook air and all of my Storage partition!

    I don't want to backup my storage partition that's why i have two different partitions.

    Any solutions?

  25. MaB
    February 8, 2015 at 1:59 pm

    Hi Tim:

    Great info but I am more of an aspirational "techie" (i do recruiting). I have a Macbook pro that the folks at the genius bar have delicately told me is "Vintage". It is old. There's a keypad thats fallen off and all my volumes (except my largest external drvie (2TB) are full.

    I need a new laptop but cant buy one just yet.

    There are a few storage problems. One is clearing out my laptop harddrive for better performance.

    I have two external drives and in reading your article i'm wondering if i can partition my data so certain data (maybe files & audio) can go one one external drive and video (i have a lot of video including itunes films and my own DVD's loaded with handbrake) onto the other so i dont have to go buy a 5TB drive and reload it with my existing data.

    Any ideas are much appreciated.

  26. Dan
    February 1, 2015 at 12:28 am

    Tim, I have a 2TB drive that I use for Time Machine. I had an old 2007 vintage iMac which I just upgraded to a new iMac 2015 model. With the old iMac, Time Machine backed it up on the 2TB drive, the backup file called D. With the new iMac, Time Machine is backing up on the 2TB drive under file called D2. My question is, how can I tell Time Machine when I want to restore a file to grab the file from file D or file D2? Is it possible?

  27. Khun
    January 24, 2015 at 10:11 am

    Hi Tim,
    I just bought 2TB Seagate External HD. I would like to know your advice for partition of my external HD into 2 partitions; 1TB for Time Machine for my Mac with 512GB SSD using Mac OS extended (journaled) format and 1T B for Windows PC/ Mac storage using ExFAT format. Is it advisable?
    Thank you in advance!


  28. Paul
    January 22, 2015 at 9:48 pm

    Hey Tim,
    Thanks for the nice article. I'm just trying to be clear on something. I had 750gb hard drive on my mac that was just stolen last week. Fortunately, I have a full time machine back up. However, I'm looking at new macs that have smaller hard drives. If I were to get one and plug in my time machine....would I be able to just pull off what I want or would it just not work? Also, do you know if all my applications would be recovered too (did a full back up, nothing unchecked)? Finally, will trying to use a computer with a more recent OS cause any troubles? Cheers!

  29. Stan
    January 7, 2015 at 11:02 pm

    I have a 2T capsule. I don't want to backup everything in my computer just certain things. I have a bunch of videos that take up 51.42GB. I also have a very large file of learning books that take up a lot of space on my MacPro. I would like to be able to remove those files from my computers HD so I can open up space on my computer. Is their a way for me to put just these 2 large files alone into the time capsule so I can access it when i need it?

    • Tim Brookes
      January 8, 2015 at 12:49 am

      You would need to repartition the Time Machine hard drive, as Time Machine uses the entire partition for its backup. If you create two partitions (as the article states) then you can dedicate one to Time Machine, and the other to storage.

      You could then move your video files and books onto the storage partition.

      Do remember that your iPhoto and iTunes libraries can also take up a lot of space, and generally need to be left on your computer (though you can change this, e.g.: //

      Does that help?


  30. Ian Conrad
    January 7, 2015 at 2:41 am

    Nice and clear post, just what I was looking for. Ended up partitioning a 1TB drive to 750GB for time machine and 250GB as exFAT for storage and other random things. I figured that's sufficient since most of what I want backed up doesn't change (majority of the space taken is from a huge amount of photos) so probably won't get re-backed up after the first run (or will it?).

    • Tim Brookes
      January 8, 2015 at 12:41 am

      You're correct Ian, after that initial chunky backup (which can take a few hours) Time Machine will only ever perform comparative backups. It looks for changes on the drive (updated/new files) and adds them to the pile. Your old versions of files will eventually start to be overwritten (starting with the oldest first) when your Time Machine fills up – everything is handled for you in this respect.

      Glad you found the article helpful.


  31. Kathy13
    January 5, 2015 at 7:07 pm

    I also found this very helpful and timely since my 13" MacBook Pro with a 256GB hard drive was almost full. I needed to upgrade to Yosemite and wanted to use some of the 1TB of space on my Time Machine Backup drive. One additional question I do have though is about all the old iterations of backups (mine go back two years currently). Can I reset an option to limit how many are stored? And, how do I delete the old ones I no longer want. I tried to move them to my Trash, but I'm not sure that really worked. Thanks!

    • Tim Brookes
      January 6, 2015 at 12:52 am

      Hi Kathy,

      Time Machine dedicates the entire drive to simply backing up data, hence why you need to partition the drive if you would like to use it for something else (in this instance, storing data). The software uses a comparative method of backup – once you've initially backed up your 256GB drive, the computer looks for changes and only backs up new data.

      Because of the way this works, Time Machine generally has a lot of space available. Most people backup laptop drives to 1TB+ externals, when their own drives are only 1/4 of the capacity. Historical backup data is simply a nice way of using that space you have already dedicated to backing up.

      Deleting old backups doesn't make much sense, because Time Machine polices itself when it comes to usage. Once your external Time Machine backup is full, it begins overwriting data – by eating into these iterative, historical backups.

      So basically, provided your Time Machine drive (or partition) is bigger than your MacBook hard drive, you can just let it sort itself out. Ignore any "Time Machine is getting full errors" too!


  32. Carl Borgstrom
    January 3, 2015 at 6:56 am

    Hi Tim,
    I have a 2 TB Seagate GoFlex external drive and partitioned it into 3 - 666 GB sections. We have an iMac (OS X 10.6), a MacBook Pro (OS X 10.8) and a MacBook (OS X 10.6).
    The iMac and MacBook Pro back up just fine, but the MacBook gets stuck, or hangs, at about 14 GB (it's only trying to back up 21 GB). I have left this overnight and it always gets hung up, so I have to Stop the Backup.
    When I look at the MacBook partition in Disk Utility, it says there is 573 GB available (meaning there is about 93 GB of data backed up?). When I Enter Time Machine, there is nothing, and in Time Machine Preferences there is no record of any backups. Any thoughts? Should I erase the entire disk and re-partition?
    BTW, I have enjoyed your insightful and clear solutions to Time Machine.

    • Tim Brookes
      January 6, 2015 at 12:43 am

      Hi Carl,

      That's an interesting one. You could try a few things, but yes – if you don't really value the historical backup data (i.e. old versions of files you have probably deleted by now) then you might get most joy from simply erasing the partition and backing up again.

      Failing that you might want to turn to more drastic measures like resetting PRAM or your SMC – //

      You might want to keep in mind that it could be a problem with the Mac... if there's corrupted data due to a drive error you've yet to notice for example!

      Good luck, let us know if you solve this one.

  33. Teresa
    December 31, 2014 at 6:19 pm

    i have a 2tb time capsule and have already started using it for time machine. can i still do the above and my guess the back ups would just start over? there is nothing else on it currently but the time machine back ups.

    • Tim Brookes
      January 2, 2015 at 2:11 am

      Hi Teresa,

      You're correct – the backups would simply start over again. You will lose your historical backup data (your Time Machine probably has old copies and versions of files long gone from your machine) but if all your important stuff is on your computer (or another hard drive) then you won't really "lose" anything.

      Provided you partition then set up Time Machine again, your machine will be backed up and you'll have some extra storage to play with.

      Good luck! Tim

  34. Parham
    December 29, 2014 at 5:48 pm

    Hi ,
    So I wish I had seen this article 4 days ago. This is why:
    I had my old laptop's back up (500GB) on my external hard drive (1TB) and bought a new laptop with 256GB storage. Since the hard drive is smaller than my old one, thought it'd be enough if I just manually copy and paste stuff that I really need. So quickly connected my hard drive to the laptop and said yes for backing up the new computer (with different name)! I thought that it would create another folder but apparently wasn't that smart. My questions are:
    1. Are my all data actually overwritten with the new one?
    2. Is there any way for me to restore the old one?


    • Tim Brookes
      January 2, 2015 at 2:33 am

      Hi Parham,

      Unfortunately your data has probably been overwritten. There are a few things you can try, not least recovery of the entire partition. There is a great free tool available to help you do this, called TestDisk (it has a cousin called PhotoRec that's perfect for recovering pictures from memory cards too).

      The key is to not write more data to the drive. The more data you write, the less likely it is you'll see the old data again. When things are deleted, they never really go anywhere – they're just marked as "writeable". You're bound to be able to recover at least some of the data.

      How to use it:

      Good luck, please let us know how it goes :)


  35. Michael Hamilton
    December 29, 2014 at 4:56 am

    Tim: best/simplest explanation I've come across in two weeks of research. Thanks!

    I'm about to set up a 4TB external plugged to my Airport Extreme router. The router serves two MacBooks wirelessly and a PC hardwired. Can I back up all three computers to the external drive. For example, one Time Machine partition @1TB will backup both macs - separately of course - will it not? Another 1TB partition to back up the PC (any good PC back up software you can recommend?). 2TB partition left for storage. Thoughts?

    • Tim Brookes
      January 2, 2015 at 2:29 am

      Hi Michael,

      Sounds promising, but I believe that Time Machine requires one partition per Mac. That shouldn't be a problem as you could just split that 1TB in the middle and create two 500GB partitions – or dip into your available storage pool if you wanted to dedicate more space to backups.

      I'm not too hot on Windows software these days so I took a look at the Best Software Page as I know Tina (our Windows Editor) has recently revamped it – //

      Looks like "FreeFileSync" is our number one choice at the moment, but there are a few alternatives there. The software works with Mac and Linux too turns out.

      Good luck with the setup!

  36. FBS
    December 27, 2014 at 3:13 pm

    Hi, very helpful. Is it possible to use time machine to back up to both partitions - so that it would back up my iMac on one partition, and my external drive that holds media files to the second partition?

  37. SB20
    December 24, 2014 at 1:17 am

    Thanks for this article Tim. I just upgraded to a bigger TM backup drive. Now I can use the extra space as backup for my other media drive.

  38. Matheus
    December 8, 2014 at 3:00 am

    So, I bought a hard drive 1tb to use for back ups. The problem is that the time machine uses both the HD and the macbook space. I was wondering if there is one way to just use the HD space, and keep my macbook free of backups.

    • Tim Brookes
      January 2, 2015 at 2:14 am

      Hi Matheus,

      Apologies for the delay in getting back to you – I wonder if you solved your problem?

      That's very strange that your Mac is backing itself up... to itself. That doesn't really make much sense! Can you launch Time Machine and take a look at the designated drives? If you have chosen "Macintosh HD" or another internal partition then deselect that. Ensure your external HDD is selected, and only your external.

      Let us know if you sorted it out :)


  39. Anonymous
    December 4, 2014 at 6:38 pm

    Very helpful thanx

  40. Lee303
    November 29, 2014 at 1:50 pm

    Nice one Tim, this article fits perfectly as I just 'upgraded' from 500 drive to a 256 solid. I only need one backup at a time so this works well. I'm only really concerned with keeping high grade music someplace, after agonising over 320 AAC being OK in my mbp (convert from AIFF). Now I have plenty space on my SSD & all music is compatible with my players (my AIFF files stored externally). Cheers!

  41. Amanda
    November 23, 2014 at 4:40 pm

    So totally useful of an article! I had questions regarding how to optimally use my recently purchased external hard drive... and this article answered everyone one of them! And the instructions are so user friendly!

    Although, I would specify the differences of what format should be used for the storage component (specified for Time Machine backup, but not for storage) since I had to find the details on another site.

    • Amy
      January 7, 2015 at 12:08 pm

      me too, a bit lost here!! what format should I use for the storage component? help would be greatly appreciated

    • Gaya
      February 2, 2015 at 7:53 am

      GUID is safe and compatible with Mac. You could try exFAT but it's not guaranteed that it will work with Mac.

  42. Chris
    November 5, 2014 at 11:49 pm

    Thanks for the note. I havent touched the hard drive since your Step 2 from this post. Do I need to repartition the external HD from step 2 on this post before I go ahead with the Test Disk Process?

    • Tim Brookes
      November 11, 2014 at 3:31 am

      Hi Chris,

      Assuming that data recovery is your number one concern, do as little as possible to the drive. This will prevent further data being written to it (over the top of your old data). At present it's highly likely the data is sitting there, but the drive has marked those sectors as "to be written".

      You'll need space of at least the size of the partition you wish to recover to do this also – you can't recover a drive to the same drive.

      Good luck! Keep us posted :)


  43. Chris
    November 1, 2014 at 10:18 am

    Tim, Is there a way to recover the NTFS portion of my external drive? I didn't start with a clean drive (600GB out of 1.5 TB used originally in ntfs). I finished step 2 and then realized that it completely changed the drive to os extended.

  44. Rob
    October 26, 2014 at 4:48 pm

    Thanks for this, Tim. Just what I was after

    August 26, 2014 at 12:04 am

    I don't get why step 2 is necessary. Isn't possible to partition the disk without erasing it???

    • rea
      August 30, 2014 at 9:10 pm

      well, yes.

    • Tim B
      September 1, 2014 at 12:25 am

      Sometimes it is, but it often goes wrong. Not all volumes behave properly when partitioned – many Windows partitions (FAT32 particularly) have been destroyed this way.

      Another reason I left this step in was to make it clear to anyone following along that they'll be losing any existing data stored on the drive. Plus, it's always nice to start fresh with these sorts of things!

    • David
      April 18, 2015 at 4:19 am

      Perhaps this was covered in earlier comments (I have not read through all of them), but it seems to me the problem with this solution is, if the external drive fails, then you would lose both all your saved file data on the drive, plus the backup Time Machine data. Pretty much defeats the purpose of doing backups at all. This is assuming we are talking about a single bay enclosure with 1 drive only. However, if we were talking about an enclosure with 2 (or more) bays, and as many drives, would there be a way to partition these so that 1 could be for file storage, and the other for Time Machine backups? What would be the step by step process for this?