I clone my Mac weekly to an external USB drive, with Carbon Copy Cloner (CCC).

Ideally, I'd use 2 separate USB drives, and alternate which I clone to each week.

But SSDs are expensive, so with just 1 drive, should I ...

  • have 2 partitions, and alternate which I clone to each week?
  • have just 1 partition / 1 clone, no alternating?

Does the alternating-partition method really provide any benefit? Any physical issue would effect both clones. And for any corruption, I could just redo the clone.

Your expert thoughts?

  • Something to consider is that it is the same drive, so if it fails or is stolen, the one physical location that stored the backup is lost. Most people would recommend having more than one physical backup device in more than one location. e.g. One daily SSD backup on one partition and one Montly SSD stored at friend's place or alternately on a cloud service.
    – adamxweb
    Apr 15, 2020 at 3:06

1 Answer 1


It’s much more important to back up your data than to make clones of your computer.

The idea is that you can get back up and running quickly even if you’re on a different computer; even if it’s a PC! A clone will be specific to your machine. If it’s a 2015 (for example) and it gets lost/stolen or sent in for repairs and a kind soul loans you a 2013 model, that clone is useless as it won’t function on an older machine.

(IMO) a clone isn’t necessary anymore especially if you’re using APFS as it has a built in snapshot feature that allows you to make an immediate point in time backup of your drive. Instead, put together a strong backup strategy that allows you to get up and running quickly.

And speaking from personal experience, while I have a Time a Machine backups, when I upgraded to Catalina I didn’t even do a migration. I took the opportunity to “tune” my new system with respect to the new shell (ZSH) new features like iCloud Drive, etc. I relied much more on my cloud files than Time Machine. That said, I still wouldn’t go a single day without having that continual TM backup.

  • Thank you for the thoughtful response. I've been doing clones for many many years now, as one component of my overall backup strategy, which also includes Time Machine, Arq to BackBlaze B2, and a monthly offsite usb-drive clone. The diversification makes me feel more secure, in case there's a problem with any one of them. Yet I also wonder which I'd actually use for a full immediate restore. The (local) clone could be a week old (semi-useless, to your point!), TM I have just never trusted beyond occasionally restoring one file, and BackBlaze could be incomplete and slow restore.
    – tex77
    Apr 15, 2020 at 14:32
  • 1
    A clone definitely can't hurt and (believe me when I say this) it actually warms my heart to hear someone taking a nice proactive approach to data protection. Just yesterday I commented on another related answer about how many posts here could be solved with a backup
    – Allan
    Apr 15, 2020 at 14:37
  • Also, re your orig reply: I'm on APFS (Mojave still), but I really don't understand the snapshots feature (how it works, how can it replace cloning, when its on the same drive?, etc). And I know Apple wants us to rely on Cloud services (iCloud.. drive, photos, music, etc) but to me that's more SYNC than BACKUP. I don't have a copy. To backup iCloud data, I need to download it - regularly (how exactly? not with Arq), and store it where exactly (outside the reach of iCloud trying to scoop it up again redundently). So I'm luddite on cloud storage.. because I don't see how it's backed up.
    – tex77
    Apr 15, 2020 at 14:48
  • 1
    I wrote another answer re: APFS snapshots vs Time Machine. You're absolutely right that Cloud ≠ Backup! Using iCloud or OneDrive as an example, you'd backup the local folder because it's synced to the cloud. So, in effect, it's in 3 places - cloud, local, and backup. In one of the answers above, I talk about a NAS so for me, data is in 4 places.
    – Allan
    Apr 15, 2020 at 14:57
  • Thanks, that APFS Snapshot vs TM answer is very helpful. My takeaway is that I'd want to continue with external clones to USB drive, as part fof my overall backup strategy. That said, I still seek input on my original question: Is there really any benefit to cloning to alternate partitions on a single drive? This does not protect from physical damage/loss. But does it really protect from data corruption / software failure, or anything else, since I could just reformat and redo the clone if needed? Context: a 500GB SSD (for 1 clone) is much cheaper than a 1TB SSD (for 2 alternating clones).
    – tex77
    Apr 15, 2020 at 17:20

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