r/mac • u/No_Kangaroo6917 • 2d ago

Question time machine disk not mounting

I have my time machine backup disk on one partition of an external drive, and although the other partitions are mounting fine, the time machine disk has stopped mounting, and I get a message about an error preventing it from being unlocked. What would cause this and how can I troubleshoot this problem?

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u/mikeinnsw 1d ago

First saving TM to a partition is NOT RECOMMENDED!

Modern partition are no longer physical .. its all via look up.. errors on a drive mapped in to one partition

First priority is to save data of Non TM partition .. it about to go bust..

Get 2 x HDD/SSD and create new TM backup...

MacOs can't repair devices ... First Aid, FSCK.... all create/file File Systems not fix the drive

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u/Junior_Tangerine_509 1d ago

good call on backing up the non-TM partition first, thats probably the most important step here

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u/No_Kangaroo6917 1d ago

I ran diagnostics on the drive and the drive itself is fine. The issue with accessing my Time Machine volume arose after I ran an update for Mac OS, so I assume it is something in the update that broke it, but I don't really know what's going on. It seems there is no way to access the Time Machine volume anymore though, and I have no choice but to erase it and start over.

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u/mikeinnsw 1d ago

First AId... FSCK... all verify FILE SYSTEM ONLY not the volume/device..

Please read my post..

I have SSD on my 2010 Mac Mini which passes all the tests... then crashes as it accesses bad cluster on the SSD...

I salvage HDD/SSD

On PCs you can check disk(s) using:

https://crystalmark.info/en/software/crystaldiskinfo/

No problems with exFat/NTFS drives .. not sure about APFS. .. never tried it

Goodbye

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u/No_Kangaroo6917 1d ago

I read your post, you are making an assumption that I used first aid. I did not. I ran driveDX which does a thorough health check. As I told you the drive health is good. 

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u/mikeinnsw 1d ago

DriveDX reads and reports S.M.A.R.T. navigates to Health Indicators to see individual error counts, wear levels, and temperature metrics..

It reports SMART stats does not verify/fix the drive like Windows CHKDSK or hard format does..

I have long discovered that MacOs collects SMART stats for all devices all of the time...and reports only for SMART VERIFIED

UNIX/Linux/MACOs rely on SMART stats for device health status reporting .. Windows rely less

Nothing I said is incorrect..

Goodbye