How to back up a Mac to an external hard drive

How to back up a Mac to an external hard drive

Backing up your Mac may just be the best form of insurance you can have on your prized device, as it not only saves your pictures and data, but your entire system from the ground up. Meaning if you ever needed to start again on a new device, you wouldn’t need to optimise all your settings, re-input all of your passwords or log back in to any apps or software you use.

Creating a backup can be done using an Apple device called Time machine or by using a third party hard drive and using software to transfer your system data. We’re going to be looking at the latter, using Time machine software built into the Mac to back up your device to a 3rd party external drive.

Backups should be done regularly, especially if you’ve just added important files to your MacBook like photos, music or videos. It is also incredibly important that you back up your Mac before you update the Operating System. OS Updates put incredible strain on your hard drive and a good number of hard drive failures happen during this time.

Preparing your External Hard Drive

Connect Drive

Firstly you’ll need to connect your external hard drive via USB or Thunderbolt port. If your hard drive is not showing up on the desktop, first check the external drive to see if it needs a separate power source to work.

If it does it will usually have a circular power port located on the drive somewhere. If your drive doesn’t need a power supply but is still not showing up, you will need to format the drive so it is compatible with Apple Mac OS.

Check Available Space

You will need to have enough space available on your external drive to handle all the data you have on your Mac. To check this, click the Apple Icon in the top left of your screen > About This Mac > Storage. You will then need to subtract the available space from total amount. For example 29 GB Available of 250.66 GB. This will mean we need around 222 GB of space on the external drive to hold the Mac backup.

You may find that you need to clear space from your external drive or potentially get a new drive that has enough space for your needs. Please remember that clearing space on your external drive by moving it onto your MacBook will not help. You can however move the data from your external drives onto other Macs. Once you make sure that the data you have moved is safe in its new location and is not corrupted, you will need to delete from your external hard drive.

If you can’t find the size of the external drive by looking at the storage device itself, you can search for disk utility using the magnifying glass in the top right and then select the drive you want to use for Time machine. This will then show you a bar of available space and space used, giving you an indication as to the size of the drive.

Format External Hard Drive

If you need to format your storage device, click the magnifying glass in the top right of your screen and search Disk Utility. Once you have the drive connected it should appear in the left hand side of the Disk Utility window. Select your desired storage device and click the Erase option in the top of the window.

On the subsequent drop down you can name the drive, ‘Time machine’ is a good name for this situation. Then make sure the two drop downs read:

Format: Mac OS Extended (Journaled)

Scheme: GUID Partition Map

Using Time machine

Once we’ve ensured the external drive is formatted and has enough space for your backup, we’re going to open up Time machine and start the backup process. To find Time machine, click the Apple logo in the top left of your screen > System Preferences > Time machine .

In Time machine, click the Select Disk drop down and click on the external hard drive you wish to use to back up your Mac. In this drop down you will be able to see all available storage devices that are attached to your iMac so ensure you are picking the right one. If you are stuck with which one you should use, go to ‘Finder’ on your dock and have a look through the different named hard drives down the left hand side until you find the option you want. Then head back to Time machine and choose said drive.

If you have used another hard drive as a Time machine before, your Mac will then ask you whether you wish to replace the last storage device with the new one or if you wish to use both together, alternating between the two with each time machine back up. This is the ultimate safety measure to ensure you always have a fresh back up if any of your hard drives fail – but isn’t likely to be necessary.

Now it’s just a waiting game. Once you’ve selected an option for hard drives it will give you a progress bar and an estimate of time needed to back up your Mac. It’s worth noting that the time estimate is usually nowhere near accurate, not because of bad software but because that time is based on the speed in which it is transferring the current file it is working on, the next files could be a lot quicker or a lot slower which will make the estimated time jump around. It’s usually safe to assume that the backup will be quicker than the time first shown by time machine.

Finally, ensure that ‘Back Up Automatically’ is ticked on the right hand side of the Time machine window. Doing this will give you the best chance of always having a new and up to date back up, offering hourly back ups for the past 24 hours, daily back ups for the last month and monthly back ups for all previous months. Your Mac Time machine has features that should allow it to intelligently manage the storage on your external drive when it is connected, automatically deleting the oldest files to make way for future backups. Meaning once you’ve finished this Time machine set up, you shouldn’t ever need to manage the back up data on your external hard drives manually to create space.

Back Up Your Mac Without Time machine

If you don’t wish to use Time machine, there are a few options in which to back up your Mac, some automatically back up data using 3rd party software downloadable through websites or the App Store on your MacBook, others more manual and a little more time consuming.

The two apps I recommend are called SuperDuper! and Carbon Copy Cloner. These are both downloadable using their websites and if paid for, work very well and are worth the price you pay.


This app works for free and includes subscriptions for different levels of service, one of the key selling points for SuperDuper! over Time machine is the support side of their software. If you have issues with a back up or getting SuperDuper! to work on a specific Mac or operating system, then you can discuss it directly with their help team and get real answers to the issues you’re having. Something that is a little too personal for Apple to offer with Time machine unfortunately.

SuperDuper! also offers more technical approaches to back ups with advanced settings like incremental backups, ‘Smart back ups’ and even ‘Checkpoint back ups’ which store your critical system settings and files at a set point in time. This way you can refer back to them instantly if you have an issue with a system or app update.

SuperDuper! is available online and not in the App Store and if you decide to try SuperDuper! rather than use Time machine, ensure you are getting it from a safe and reliable source. It has a free trial version as well as the Pro version for between £20-£30.

Carbon Copy Cloner

Carbon Copy Cloner (CCC) features a great variety of options with your back ups if you want things a bit more technical and precise than you can get with Time machine. This paid for software offers 30 days free trial before paying £30-£40 one off charge to gain life time access to the software for your whole household or workplace.

CCC is capable of doing back ups from one external drive to another and also from Mac to Mac. Other features include the ‘Snapshot’ feature which allows you to take a full system back up at key points in case you have issues and want to revert back to a specific time. CCC also prides itself on its transfer speed from computer to external drive or any of the other variations mentioned above.


This should be enough knowledge to get you started in the much needed world of data back up and failsafes for your system files.

Time machine is one of the most underrated and life saving features that your Mac has to offer and unfortunately most people do not feel the real weight of this until the worst happens. There are many great tech repair specialists and data recovery experts out there but the simple answer is that having to get data back without the use of Time machine or 3rd party backup software is both time consuming and potentially incredibly expensive.

Fortunately for you, you’re well ahead of this potential catastrophe by looking into Time machine off your own back.

As with all my blogs, if you have any issues or questions you can get in touch with us here at Hero Tech Support and we’ll always do everything we possibly can to solve your problems and answer your queries.

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Greg Doulton

Greg is an Apple repair specialist and has wealth of knowledge within the industry. Follow the blog for more news and tips.

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