Is it possible to change the UUID of an APFS Container and Volume? [Sequoia]

Question

Is it possible to change the UUID of an APFS Container and Volume? [Sequoia]

After a lot of trouble, I was able to clone my APFS Time Machine onto a new, larger disk. But the only way I could do that was to use dd(1).

But that created a binary copy, so the Container, Physical Store, and Volume all have the same UUIDs as the original.

Is there any way of changing those UUIDs?

It might not be strictly necessary; I plan on keeping the older/smaller Time Machine until I'm confident the new/larger one isn't corrupt, but I have no reason to ever had them mounted simultaneously, so the duplicated UUIDs shouldn't cause a problem — although if I'm missing something, and that could cause a problem, please educate me.

Note: this is for an APFS-formatted disk, so tools for older formats won't help me. Specifically, Sequoia still contains the manpage for csunique(8), but this was for the CoreStorage volume management system, and was deprecated as of High Sierra (10.13).

Mac mini, macOS 15.6

Posted on Sep 1, 2025 07:46 PM

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Answer 1

den.thed

Level 10

88,810 points

Sep 2, 2025 08:51 AM in response to Richard Wood (bis)

Time Machine backups can not be copied to a new drive.

If you think that you might need something from the old Time Machine backups at a later date. Then set the old Time Machine drive aside and start new backups on the new external drive.

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Answer 2

Sep 2, 2025 11:13 AM in response to Richard Wood (bis)

Richard Wood (bis) wrote:

After a lot of trouble, I was able to clone my APFS Time Machine onto a new, larger disk.

why?

Start a new backup on a new drive and you will have no issue to contend with.

If you value your user data

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

More than one device, more than one backup methodology.

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Answer 3

lkrupp

Level 7

21,253 points

Sep 2, 2025 11:25 AM in response to Richard Wood (bis)

You cannot do what you want you want to do, period. Time Machine is what it is and it will not accept coned copies. As others have said, start new Time Machine back up on different drive if you want to keep data on the old one.

Macs don’t work the way they used to anymore. macOS has become more and more locked down for security and privacy issues. Old timers like me have learned to adapt to the new ways.

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Answer 4

Sep 2, 2025 07:59 PM in response to leroydouglas

Great advice.

My off-site backup HDD is in my brother-in-law's gun safe, and I've swapped it at least every six months since shortly after Time Machine was first available. I knew I might lose a few months of data, but at least the 40,000 songs in my iTunes would be safe.

Last year while I was moving to another state, a storage unit was broken into and I lost a lot of my possessions, including the previous Mac. I did start a new TM, but I wanted to clone the one I'd pulled out of the safe so I'd have, at hand, the data that goes back before that theft. I was concerned files I'd innocently deleted before the theft might be important for my insurance claim. They weren't, it turned out, but I still like having the "Time Machine" aspect of old data available to me.

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Answer 5

Sep 2, 2025 08:04 PM in response to lkrupp

Sequoia did accepted the cloned drive, and it seems to be working properly. As I said in my reply to my OP, I'm interested in why this seldom works — and might still fail due to a hidden flaw in the cloned copy — but I suspect the problem is that there are so many possible uses cases for "cloning" (e.g., "I want to clone the TM I have on an HDD RAID array onto one SSD drive") that everyone has just thrown their hands up. Dunno.

But since I've been using unix machines since the late 1970s, I wanted to try it.

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Answer 6

Barney-15E

Level 10

121,250 points

Sep 2, 2025 08:34 PM in response to Richard Wood (bis)

Richard Wood (bis) wrote:

Sequoia did accepted the cloned drive, and it seems to be working properly.

What is involved in “working properly?”

Often with unsupported Time Machine antics, it all appears to be fine until you need to restore.

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Answer 7

Sep 2, 2025 09:10 PM in response to Barney-15E

Hmm, I replied to my OP with those details, but I don't see that.

After the dd completed, I used the stand-alone version of DiskUtility to run a First Aid sweep, and it passed that.

Then I started up Sequoia and noticed that the cloned Time Machine had been recognized by Sequoia, so I initiated a manual "Back Up Now", which completed without problem. I turned back on the one-hour interval, and it has done another backup since then.

I also opened up the Time Machine and retrieved several files from different parts of the file system and different dates, including all the way back to Day Zero of the archive.

I haven't attempted a Restore to my system with the drive, which I agree would probably be the ultimate test. Since that would take quite a few more hours of not being able to actually use my computer, I might not get around to trying that test.

I still do have the source drive for the clone, so I have that backup in case of a system failure.

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Answer 8

Barney-15E

Level 10

121,250 points

Sep 3, 2025 06:24 AM in response to Richard Wood (bis)

Interesting discovery. I would have tried asr, but have never found any reason to duplicate my backup drives.

What options did you use for dd? Posting the full command might be useful for others seeking a solution to that problem.

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Answer 9

Sep 2, 2025 09:09 AM in response to Richard Wood (bis)

I agree with den.thed that it is best to start a new backup rather than mess with the old and potentially corrupt it.

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