tmutil snapshot hangs up (TimeMachine, SuperDuper, backup)

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tmutil snapshot hangs up (TimeMachine, SuperDuper, backup)

Since updating to Catalina I faced some issue with my iMac. Even a clean install did not solve the problem. After some investigating the problem is reproduceable. It is about tmutil, which is used by time machine and SuperDuper to create snapshots and backups:

Usually executing 'tmutil snapshot' will immediately create a snapshot. However, after e.g. a sleep mode the execution of 'tmutil snapshot' will just last forever. Backups will fail and so will shutting down the computer - until a hard restart. Also a 'tmutil listlocalsnapshots /' just keeps running without result.

Any hints whats going on here? Seems something is happening in the background, but no idea what...

iMac Line (2012 and Later)

Posted on Dec 29, 2020 11:50 AM

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Answer 1

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HWTech

Level 9

55,934 points

Dec 29, 2020 12:34 PM in response to wende60

Run Disk Utility First Aid on the drive. Even if First Aid reports everything as "Ok" click on "Show Details" to look for any unfixed errors.

Run the Apple Diagnostics.

It is also possible you may have a failing drive or some type of software issue. Run DriveDx and EtreCheck and post both reports here using the "Additional Text" icon which looks like a piece of paper.

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Answer 2

wende60 Author

Level 1

4 points

Jan 1, 2021 6:53 AM in response to HWTech

hi again,

first of all: Happy New Year :)

Did not run drivDX so far, have to get familiar first with that tool.

Hardware check (starting with "D") was without anny issues

First Help startet via Commanfd + R was without any issues

EtreCheck seems to be fine as well (unsigned stuff is from my side, an Electron app and an Apple script, both running fine)

ErtreCheck

Hope this is the way to provide the logs here...

regards, Jo

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Answer 3

HWTech

Level 9

55,934 points

Jan 1, 2021 10:34 AM in response to wende60

I don't see any issues with those reports that would cause a snapshot issue although this Mac has had several app crashes & high CPU usage.

When you performed the clean install did you erase the whole physical drive or just the partitions/volumes? The whole physical drive needs to be erased to make sure the you have a fresh APFS file system throughout. Did you test the system before restoring or migrating from a backup or before installing any third party apps?

If you erased the whole physical drive and tested before installing third party apps and restoring/migrating from a backup and still had issues, then I suggest performing a clean install of macOS to an external drive and testing the snapshot feature. If this works, then there is most likely something wrong with the internal drive that doesn't show up in the reports. If you still have an issue with snapshots, then you have some other sort of hardware issue (power, Logic Board, or perhaps memory).

You can try performing a memory test using Memtest86. Use the downloaded Memtest86 .iso file as a source for Etcher which will create a bootable Memtest86 USB drive. Option Boot the Memtest86 USB drive and select the orange icon labeled "EFI". Maybe this extended memory test will detect some issue with the installed memory.

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Answer 4

wende60 Author

Level 1

4 points

Dec 30, 2020 9:47 AM in response to wende60

the diagnostic tools do not provide any helpful results, everything should to be fine.

Additional info: after running into the above described problems the tmutil process is hanging and there is no way to kill it. Even a 'sudo kill -9 [PID]' does not stop the process, and while this process is still running a shut down of the Mac fails too of course, finally I have to press the button.

I never had an issue like this before. How can it happen that a process can't be killed?

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Answer 5

HWTech

Level 9

55,934 points

Dec 30, 2020 5:19 PM in response to wende60

Did you run First Aid on the drive? I recommend running First Aid on the hidden Container and checking for any unfixed APFS errors. If the file system has issues, then "tmutil" will have issues as well since it is leveraging the APFS snapshotting feature.

I have seen macOS not kill a stuck process several times. I don't know why other than the stuck process is affecting more of the system.

You should also run DriveDx and EtreCheck and post their reports here. Maybe you have a hard drive issue or an issue with some third party software.

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Answer 6

wende60 Author

Level 1

4 points

Jan 3, 2021 9:24 AM in response to HWTech

hi again,

I did the clean install twice since I was not familiar with the APFS format ;) The second time i deleted all partitions and reset the HD to Mac OS Extended (The install process of course re-created the APFS partitions again).

All the issues came up after updating to Catalina, and they did not really disappear after the clean install. Since I had nothing like this with High Sierra, I still do not believe in Hardware issues. Btw: when tmutil was freezing also EtreCheck was never comming to an end!

My plan now was to roll back, the stick with High Sierra already was prepared. But before i did so, i updated to Big Sur as a last tryout. And believe it or not: the issues seem to be gone now. No more freezing of tmutil after computer's sleep mode, no freezing when shutting down the computer so far. TimeMachine and now CCC5 (as SuperDuper is not ready for Big Sur yet) work as expected.

Catalina was an epic fail to me. Using Big Sur my Mac world is in balance again ;)

However, thanks for your thoughts and hints, much apprechiated :)

kind regards, Jo

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Answer 7

wende60 Author

Level 1

4 points

Jan 1, 2021 7:14 AM in response to wende60

and here we go with the DriveDX report. Did tot check the USB devices yet, but since the issue occours also if every external stuff is unplugged it seems to be not relevant...

DriveDX

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tmutil snapshot hangs up (TimeMachine, SuperDuper, backup)

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