How to make a bootable backup of your computer


There are two main ways to backup your Apple computer.

1. Use Time Machine to automatically backup. This is the Apple way – the easy way.


2. Manually backup your computer with some other software such as Super Duper or Carbon Copy Cloner.

If you are a beginner I recommend Time Machine. Look here.

Apple’s way (Time Machine) is a lot simpler. It’s automatic. It doesn’t rely on you remembering to do anything. The big disadvantage  is that the backup is not bootable.  So if your computer crashes you need to insert the original DVD and restore from the Time Machine backup. This process can take hours – not good if you are just heading out the door and need a file. But it will get your computer back to what it was like the hour before it crashed!

The second method takes a few steps longer to set up, but  your backup will be bootable. That means if  you plug your backup drive in, and then hold down Option-Command-Shift-Delete during startup,  you can boot instantly off your backup drive. In an emergency you can plug in your backup and be running from it under a minute. You can’t do this with Time Machine. The downside it it will only take you back to THE LAST TIME YOU BACKED UP.

I do both. I have time-machine running so my most recent work is always backed up, and I do a CCC backup monthly so I have an instant bootable backup ready to go for emergencies.

This article describes how to manually backing up using Super Duper. If you want to use Time Machine as well, here’s an article on how to backup using time-machine.

To make a bootable backup you need to:

  1. Buy an external hard drive
  2. Format the hard drive
  3. Download some backup software
  4. Backup your Hard Drive
  5. Run the backup software often

Now let me explain those steps in more detail.

1. Buy an external hard drive

You need an external hard drive at least as big as the hard drive on the computer you are intending to back up. Eg if you have an 200G hard drive on your imac, you should get at least an 200G for your backups. This way you will always fit your backup on the external drive.

2. Format the hard drive

Plug in your new hard drive. Run Disk Utility (in your Applications/Utilities folder). Select your new Hard Drive in the left pane.

Before you format it, check in the bottom right of the window that it says “Partition Map Scheme : GUID Partition Table”. If it doesn’t go to the partition tab, choose ‘1 Partition’ choose ‘options’, and make sure it is set to ‘GUID Partition Table’ then ‘Apply’.

Now in the Erase tab check it says ‘Mac OS Extended (Journaled)’ as below, type in the name you would like to call it e.g. “Backup” and press Erase. It will now erase and format your external Hard Drive ready for use and call it Backup.



3. Download some backup software
Go to and download the latest version of SuperSooper. It’s free to be able to do a basic backup, or you can pay if you want extra features such as incremental backup (it’s faster, but the end result is the same).

4. Backup your Hard Drive

Run SuperDuper.

Select your Macintosh HD in the left menu, select your new firewire drive in the right one, select ‘backup – all files’. Press copy now, go and have a cup of coffee while you wait for it to copy all your files, perhaps up to an hour or so.




It’s good to select ‘Repair permissions before copying in the options tab, see below. This makes sure your OS X is functioning well before you back it up, otherwise there can be some problems.



5. Run the backup software often
The most important thing about backing up is to do it regularly. It’s also a good idea to do a backup before you install any new system software in case something goes wrong in the installation so you can go back to what it was when you backed up.


How do I use the backup in an emergency?

  • Plug in your external drive. Go to System Preferences, select ‘Startup Disk’, select your external Backup, press Restart.


  • Plug in your Hard disk and Press Option during startup. This will bypass the primary startup volume and seek a different startup volume such as the external one.

You are now running from your backup.

You can now run Disk Utility and erase your main Macintosh HD, then run Superdooper and backup from your Backup to Macintosh HD. When the backup is finished, select Machintosh HD, and restart. You will now be running from your main computer again.

You might want to print these instructions out, so they are handy in an emergency. It’s no use having the instructions on how to boot in an emergency on your computer – you won’t be able to read them. Don’t laugh, I’ve done it!

Here’s an article on how to use time-machine.


81 responses to “How to make a bootable backup of your computer”

  1. Cass

    when i try to load from my TM as a start up disc it doesn’t show up in the list and the newer computer I’m running from does not have enough HD space to restore my back up! Any advice on how i can run my external as the startup?

    1. No – you can’t use a Time Machine backup as a startup drive. That’s what this article is about – a bootable drive needs to be a clone of your drive not a Time Machine backup. That’s why it’s handy to make a ‘bootable’ backup. You can boot off any bootable backup though (even a USB system installer thumb drive) and then restore from time machine.

  2. Wondering

    Due to a HD failure, I just had to install a new internal HD on my macbook (running snow leopard) and did a restore from TM onto new HD.
    (New HD is 1TB, old HD was 750)

    The “old” external HD that I used for the TM backup (1TB, partitioned with a clone of my “old” “old” HD — was too small to run Snow Leopard, etc.) is now telling me that it’s outta room when I run TM.

    Question: I have an unused external 1TB drive. Will this be enough space for my “new” TM backup?
    My new internal HD currently reports 596.57 GB free of 999.86 GB.

    Am thinking that once I have a separate TM external drive (which seems to be the reco) that I can erase the old bootable clone from the old external hard drive and create a new bootable clone of the current system there? Or will it not do that bc the new internal is 1TB (even though the actual usage on it is far less) ??

    I guess for right this moment I want TM to start running. If I need to purchase another external HD I will. ;-)

    Thanks for your input!!

    1. Yes and yes to both those questions. But Time Machine will start deleting older backups when the drive is full. So the larger the drive, the further back the backups will go.

  3. Really helpful. I also recommend that you can use your old PC act as the external disk. Use an application called Mac time capsule, it enables time machine backup mac to pc. You can download the software from many download website.

  4. William

    Hi. thanks for the article. I’m a little confused as to what hard drive to use. I read that some are not able to boot macs. I have two old Seagate drives that connect via USB2. Will they work? Is there a way to check a backup will work once it’s made?

    thank you

    1. System Preferences: Startup Disk, if it appears you can boot from it.

  5. AG

    Any idea on whether I can use this to backup a 2011 MacBook Pro and then use the backup disk to boot up a 2013 MacBook Pro. Obviously the two have different HW inside, does OS X choke on it or “re-discover” the new HW when booting up and live happily? I have done it a while back on for Windows Server for Admins. You could create a deployable backup of a machine that only re-ran the last few OS installations steps of HW discovery when you started it up on a new machine.

  6. CD

    Hi Wayne!

    Recently, I decided to replace my old MacBook Pro’s 120GB internal HD with a new 500GB internal HD. I did copious (or so I thought) research on how to proceed and went with the SuperDuper clone route. Everything worked great…until I connected to TimeMachine. It deleted ALL of my old backups (some of which went back years!!), kept the most recent backup I made before replacing the HD, and then said the latest backup failed because “this latest backup is too large for the backup disc. The backup requires 126.35GB but only 39.25GB are available.” Because this was a clone why did it try to do a new full backup without asking me if I wanted to start a new set? I’ve now lost all of my old backups. I bought a new external HD yesterday and will be using this from now on for TimeMachine so this is all semantics but what went wrong? Or did it go right and I just wasn’t informed enough? Nobody ever said to expect or plan for this. And I guess all of my “deleted” backups are unrecoverable? Thanks for any insights you can provide.

    1. Yes it tries to start a new set of backups if you replace your drive. But I don’t think it will have deleted your old backups – just started a new set with the new drive. This may help.

      1. CD

        Hi Wayne,

        Thanks for your reply. Unfortunately, I’m pretty sure they were deleted. I checked in the backups.backupdb/Mac folder on the drive and there’s only one folder in there which is dated 10/04/14, the very last update I did before I replaced the drive. As a comparison, a separate external drive I use for my work Mac has multiple folders dated for each backup. Oh well, live and learn.

  7. Chris

    Down to use SuperDuper free version to see how it works, but cant get past the buy now screen, even after clicking “pay later”…any ideas? thank you

  8. Ron


    I have a 27″ imac with 10.8.5 that just crashed, can only open in Safe Mode. HD doesn’t appear as a Startup option (only shows external TM disk), resetting PRAM doesn’t seem to help. I have a TM external backup from earlier today but nothing cloned from internal HD, so not sure how I can get the internal HD back as a Startup volume to boot from.

    Haven’t tried Target Disk mode from my MB Air, but not sure if that’s necessary since I have TM. I can click on the Mac HD in Safe Mode and see all my files, so really don’t want to erase/reformat anything if I don’t have to.

    help please..

    1. Boot into recovery mode ( Otherwise get to a friends mac and make a bootable usb stick. ( Then restore form time machine.

      1. Ron

        Wayne, thanks, I was able to boot into TM from my external HD. Not sure if this is easier than using a bootable USB, but I’m going to make one anyway for the future. Didn’t know you could make a bootable USB from a different mac ( even if it has the same 10.8.5?). Wouldn’t it have computer-specific settings?

  9. Kevin

    Hi, I am looking at buying an external hard drive to both backup and incase of internal hard drive failure to boot from external drive. I want to use Carbon copy and they have insisted that the external hard drive needs to be able to reboot OSX. I can’t seem to find a hard drive that confirms that it will reboot OSX, can you suggest any drives that I may use.

    1. It doesn’t matter which one, I don’t know of any external USB drives that don’t work with a mac. You can just re-format it as Macintosh using Disk Utility after you get it. Don’t get a network drive, just a simple plain USB or thunderbolt.

  10. Dawn

    i am trying to replace my MacBook Pro hard drive with a faster sad drive. Is there any way to make a bootable “partial clone” like I just want the os, system info and key software? I feel a lot of the current hard drive is full with unknowns.


    1. Dawn

      Ssd drive*

    2. The 2 options are pretty much do a full copy, then delete what you don’t want (delete specific folders and apps), or do a new install of OS X and then move across what you do want. There’s no automatic way to just copy the core or essential things across that I know of. Migration assistant gives you some choice, but not a lot.

  11. Pat

    Thanks for the clear and simple exposé, but I am at stage 1 and cannot find in Disk Utility anything in the erase window about the format GUIG you speak about. (Mavericks, MBA 2011). Can I just erase my (new) Disk? Western Digial aslso suggest to integrate their app.

  12. Pat

    Thanks for the clear and simple exposé. I am at stage 1 and cannot find, in Disk Utility, anything in the erase window about the format GUID you speak about. (Mavericks, MBA 2011). Should I just erase my (new) Disk without any specification? Western Digial aslso suggest to integrate their app.

    1. Click on the top most icon for the disk in the left window, not the second icon.
      Click on ‘Partition’
      Under ‘Partition Layout’ select ‘1 Partition’
      Click on ‘Options’
      Then GUID.
      Don’t use their App.

  13. Jerry

    Nice, monthly disk snapshots plus Time Machine incremental backups.

    How would you restore from a monthly snapshot then the latest changes from Time Machine?

    1. You wouldn’t do that, you’d just restore from the most recent time machine backup. The monthly snapshots are for if your time machine backup fails.

  14. John Chapman

    Hi – excellent piece!

    I have an external hard drive for backups and a Macbook Pro. If I make a bootable drive using super duper, can I install that hard drive in another macbook I have just bought and use it as its resident drive?

    I plan to back up this mac, convert the second drive to bootable, then put in Macbook 2. Hope this makes sense – I have software on MB1 which I can’t replace.


  15. Matthew

    It´s good to know how to make a bootable backup. However, does anyone know if it´s possible to restore from a disk image of your system hard drive (made in Disk Utility) by starting up from, say, a USB thumb drive, then restoring the image to the internal hard drive after wiping it clean?

  16. Pierre

    Hi, thank you for this detailed topic, very helpful. It made my mind more clear.
    I can expose what I would like to get:
    I have a macbook pro with 500Gb HD Moutain Lion that is almost full and would like to
    – prepare a bootable clone
    – free some space by moving old folders occupying 25% of present HD

    I have in hand a 500Gb for current running time machine (but now running out of space) and about to buy a 1Tb drive.

    I do not necessary want to continue running TM.

    My thoughts are to get the 1Tb turned into a bootable clone, that I will renew monthly. I would prepare first this HD with a partition A of 550Gb size, a partition B of 400 Gb size and an (optional) partition C of 50Gb for exchange with PC world.
    Once the clone n1 is prepared on the partition A of 1Tb HD, the HD 500Gb would be erased from its TM backups and will be used to free space on the Mac by moving old folders from Mac to the 500Gb HD.
    So far it is seems OK. But since in the clone n2 and following, the old folders will have been removed, I need to backup the 500Gb HD.
    Question: Shall I use partition B of 1Tb HD to backup folder from 500Gb HD?
    Do you have any comments on the respective sizes of partitions A and B of 1Tb HD (i.e. is the size of 550Gb not a bit excessive to perform only a bootable clone of 500Gb drive? )

    Thank you for your answer and comments on this situation.

    1. That all sounds OK, unless you plan on using this new hard drive on a daily basis.
      IF that were the case I’d keep it seperate from my monthly backup – ie not just a seperate partition but a seperate drive.

      The broad principles are:

      You want a backup on a completely seperate drive, not on a partition on the same drive as a drive that you regularly use.

      Don’t partition unless you absolutely need to because a larger drive runs faster and more efficiently then a large drive split into 2 partitions.

      Best to have 2 clone backups and alternate to each one.

      I’d still keep a time machine going even if you do a monthly backup because if you lose an important file you were using yesterday, Time Machine will save that but the monthly backup wont.

      1. Pierre

        Thank you Wayne for your answer.

        I understand these main principles. But your answer is not clear about the hard disk supposed to host the bootable clone: is it possible to get 2 partitions, one to be a regular bootable backup, and the second for 2nd backup of another smaller hardrive?
        Otherwise your suggestions are valuable, but it would inflate the number of copies I need: 2 HD for clones, 1 for time machine, 1 to host the folder I want to remove from the Mac to save space and 1 to backup this folder. A total of 5 HD, that I am not ready to manage yet.

      2. Yes you can partition a hard disk and still have it as a bootable clone.

  17. Hi,
    Many thanks for your exposé! I have been using Carbon Copy Cloner to clone my Mac Pro to a new SDD Crucial MX200 and everything went well until I wanted to reboot on my new drive. I can not select the new SDD drive from startup utility. I see it but can’t select it, It remains grey! Can you please tell me if I have missed something ?

    1. Check you formatted it at “Mac OS Extended (Journaled)” with “GUID Partition Table”
      Also check all the System files were selected to be copied.
      (Under step 4 marks sure all the files were selected. Maybe try Step 4 again.)

      1. Thank you Wayne. I have the latest version of El Capitan OS 10. During the formatting, it propose only the option to select “Guid Partition Map” I dont have the option of “GUID Partition Table” Can you please advice?

  18. I tried both Carbon Copy Cloner and SuperDuper! Neither would run on my Mac PowerPC G4.
    I have the latest version of Mac OS 10.4. I cannot upgrade to a later OS, as I must have the ability to use “Classic” to run my System 9 software, and OS 10.4.11 is the latest system that will run Classic. (I have 20 years of work on System 9 software!)
    My hard drive is now crashing more and more frequently. I have a good backup drive, but I cannot make it bootable.
    I also have a separate System 9 hard drive that used to be bootable on this computer, but it doesn’t appear in the “Startup Disk” dialog.
    Any help will be greatly appreciated!

    1. You should be able to download an OLDER version of carbon copy cloner from here that will work with 10.4.
      Get Carbon Copy Cloner 3.5

      It’s down the bottom of the page and it’s free.

  19. itasara

    I’ve used super duper for many years. I have a newer MBP that I bought last year.I also have a newer external HD by Toshiba. SuperDuper won’t let me make my backup a bootable one. That option is greyed out. I’m not sure why? Is it b/c this computer uses the usb-C connections? I connect the external HD with usb with an attachment that converts it to usb-C. I couldn’t find any direct C devices except for this one that came with the adapter. Is it the newer iOS system? I’m using 10.14.3 at the moment.

  20. Hello, Thanks for all the great info on your site. Very helpful.

    I just purchases Superduper app and created a bootable backup on my 4T external drive. I also have TM running and a few online programs running as extra backups. My question is, i currently have:

    1. SSD drive
    2. 6T drive (only 1.5T used)
    3. 2Tdrive – not using at the moment

    on my mac pro.

    Is it possible or correct to create 2-volumes on my 4T and add the 6T drive via superduper app?

  21. Benny

    Hi, I’m running macOS Monterey, version 12.1. When I go to boot off my external drive, the error I get is “No Admin user available”. I created an user called “Admin” and gave it adminstrator role on this MacBook but I’m still getting the same error. Any thoughts?

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