What if something goes wrong and you need immediate on-site access to a full backup of your Mac’s startup volume or an external drive, and you need to get back to work ASAP? The introduction of the Apple silicon made it difficult to create a drive that you could swap out and boot from, but that shouldn’t stop you from making a backup that will get you back to work. (There are workarounds, but it requires ongoing effort.)
The best option for having a nearly hot-swappable copy of your most important data stored locally is a clone. A clone is an exact copy of a volume’s current state—a snapshot, in effect. Time Machine offers a form of this capability, but it also archives older files. You can configure the cloning software to keep only an up-to-date copy of the drive you want to mirror and nothing more.
I’ve been using Carbon Copy Cloner, or CCC ($49.99), for years. It supports cloning and a number of related features, like archiving. An alternative is SuperDuper! ($27.95), which is more narrowly focused on volume cloning. With the apps, you choose a source (usually a volume) and a destination, set a schedule, and configure tricky options, like verifying files after copying in CCC.
Cloning lets you use a drive that’s no larger than the drive you’re copying from for cloning, unlike Time Machine and other backup software’s archive modes, which require space to store multiple versions of files over time. (Time Machine always archives older files until a backup volume starts to fill up, and then purges the oldest versions of archived files first.)
I’ve found that cloning software has a reliability advantage over Time Machine, which stores data in time-stamped snapshots. If your startup volume fails and your Mac is still working, you can use an external drive, install macOS on it, and use Migration Assistant during setup to import files. However, I’ve run into issues on several occasions when Migration Assistant won’t recognize what appears to be an up-to-date Time Machine copy of my startup volume. I’ve turned to a cloned backup of that volume, which works compatibly with Migration Assistant and doesn’t seem to fail under the same circumstances. I’ve been grateful to have that extra copy.
One igamesnews reader asked, in particular, how to set up a quickly accessible external drive in case the drive they kept their Photos library on failed. Could they immediately switch to a clone that had been updated on the other drive? Yes, and that’s a great goal for a clone.
In this scenario, you can quit Photos (if the app hasn’t already notified you of a problem and quit), eject the faulty drive, launch Photos while holding down the Option key, and select the Photos library file on the cloned drive. Depending on how often you set the clone operation, you may lose little to no work. With iCloud Photos enabled, you’ll also need to set the cloned library as your system library in > Photos > Settings > General by clicking Use as system photo library.
You can also do deep scan operations with clones, copying just a portion of a volume instead of the entire thing. I had a Photos library crash in 2021 that took me hours to recover from, and then days to get back to normal. Something in my Photos library package was so corrupted that even restoring from a Time Machine backup failed. In the end, I had to rebuild everything from scratch and let Photos sync with iCloud to recover all my images and videos. Vowing never to let that happen again, I set up a nightly clone of my Photos library package stored locally on a large external hard drive. Although the hard drive is slow, the clone updates overnight, so it doesn’t overlap with my day job.
Carbon Copy Cloner gives me an extra set of braces on my photo library backup by making an exact copy, updating any changed files for efficiency, every night.
Carbon Copy Cloner gives me an extra set of braces on my photo library backup by making an exact copy, updating any changed files for efficiency, every night.
Foundry
Carbon Copy Cloner gives me an extra set of braces on my photo library backup by making an exact copy, updating any changed files for efficiency, every night.
Foundry
Foundry
Since a simple clone doesn’t let you go back, I highly recommend having at least two other forms of backup. Time Machine is the easiest for a Mac owner. Add to that Backblaze or another encrypted online backup service. Or, if you keep all your documents and images in a sync service (iCloud Photos/iCloud Drive, Dropbox, Google Drive/Google Photos, etc.), you can rely on that as a second backup.
This Mac 911 article is a response to a question submitted by igamesnews reader Michael.
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