According to Apple, today is OS X Mountain Lion release day, which means tomorrow will be “OH GOD MY HARD DRIVE JUST WENT TO CRAP AND I’VE LOST EVERYTHING” day for quite a few people. Here are some facts: hard drives sometimes die; installs—especially for entire operating systems—can go horribly wrong; data is very easy to lose. To be fair, relatively few people suffer from such problems, but that won’t be comforting if you lose all your movies/music/photos/email/documents.

Here’s one more fact: if you back-up and/or clone your Mac, each data copy reduces the likelihood of permanent data loss. And another: doing so is relatively inexpensive and not that difficult.

My advice when it comes to a new version of OS X is much the same as it was last year: buy an external hard drive (which can cost as little as £40) and ensure you at the very least have a full back-up of your Mac before upgrading to Mountain Lion. If possible, I recommend using software that clones your Mac’s hard drive rather than simply backing up the data, because that leaves you with a bootable drive if something goes very wrong. (Time Machine does enable data restoration, but the back-up drive itself is not bootable.) The steps are:

1. Format your drive using Disk Utility

Launch Disk Utility and select the back-up drive from the sidebar. At the foot of the window, check its Partition Map Scheme is GUID Partition Table, which will enable you to use the disk to start-up an Intel Mac. If it shows something else, click ‘Partition’, select ‘1 Partition’ from the ‘Volume Scheme’ menu, click ‘Options’ and select ‘GUID Partition Table’. Click ‘OK’. Name the volume using the ‘Name’ field and then click ‘Apply’ to reformat your disk.

2. Clone your Mac’s hard drive

Use either SuperDuper! ($27.95) or Carbon Copy Cloner ($39.95) to clone your Mac. If using SuperDuper!, select your Mac’s hard drive from the ‘Copy’ menu and your back-up drive from the ‘to’ menu. Select ‘Backup – all files’ from the ‘using’ menu. Click ‘Copy Now’. If using Carbon Copy Cloner, select your Mac’s drive from the ‘Source Disk’ menu and the back-up drive from the ‘Target Disk’ menu. Click ‘Clone’. The process may take several hours and it’s best to not have any active apps running (i.e. do not work on projects and save things, nor download anything while the initial clone is being made).

3. Reboot and test

Once the clone is complete, restart your Mac while holding the Option key (also labelled ‘Alt’) and choose your back-up drive as the boot volume. It will take longer than usual for your Mac to start from this external drive. Ensure the back-up works: test some apps and launch some files. Once you’re done, reboot back into your Mac’s drive.

Should your Mountain Lion install not work, you now have a bootable clone that will enable you to continue working, or from which you can clone everything back to your Mac. However, once you have a clone, you should continue safeguarding your data daily by using incremental updating (whereby only files that have changed are cloned to the external volume). SuperDuper! refers to this feature as ‘Smart Update’, accessed in the main pane’s ‘Options’ button; Carbon Copy Cloner has an ‘Incremental backup of selected items’ setting within ‘Cloning options’. Both apps have automated scheduling capabilities.

As noted earlier, more back-ups and clones reduce risk, and so if you can afford it, use multiple cloning drives and switch them regularly. Add a Time Machine back-up alongside your clones. Also consider online back-up services such as CrashPlan. This might all seem a little paranoid, but for the sake of a couple of hard drives, a piece of OS X software, an online back-up service and a few hours of your time, your data will be as safe as it’s ever going to be. Really, that’s not paranoia, but common sense.