Why am I unable to repair an external SSD in disk utility after improper ejection?

Question

Why am I unable to repair an external SSD in disk utility after improper ejection?

There is a problem I come accross whenever an external SSD is not ejected from within Mac OS. The SSD does not appear in finder but it does appear in disk utility, however, it isn't possible to fix the drive even with disk utility/first aid, trying to fix just leads to errors. The only way to solve it is to use a Windows machine to scan and repair the drive. Basically I just want to know why this happens. Luckily for me I own both Windows and Mac machines so in my case it is a minor inconvenience, but what about those who soley use Mac, how do they solve this issue? The drives don't need to be reformatted nor are they corrupt, it seems to be a compatibility thing as I also have an external NVME drive which isn't affected.

My devices:

Samsung T5 & T7 Portable SSD's - exFat file system

2016 Intel MacBook - Monterey

2020 M1 Mac mini - Monterey

2019 iPad Pro - iOS 15

MacBook Pro

Posted on Sep 5, 2022 10:06 PM

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Answer 1

Owl-53

Level 10

100,627 points

Sep 6, 2022 4:52 AM in response to Rav1oliRav1oli

When External Drive are not ejected properly as in UnMount - the Partition Map of the External Drive may become corrupted.

Therefore - Finder may not see the external Drive but Disk Utilities will still see the drive but you discovered can not Repair the Drive.

Since the use has discovered, moving the problematic Drive to Windows based computer maybe able to repair the Drive but the Partition Map of the drive does not appear to be corrected when moved to the Apple Computer.

Suggestion if you Erase the Entire External Drive on the Apple Computer and lay down a New Partition Map using the exFat drive format

Erase and reformat a storage device in Disk Utility on Mac

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Answer 2

Barney-15E

Level 10

121,400 points

Sep 6, 2022 10:53 AM in response to Rav1oliRav1oli

Mac OS Mount’s all external drives with write cache enabled. If you disconnect the drive before, the right cash is completed, it will corrupt the drive. Even if finder has said, it has completed writing to the drive, It’s really only completed writing to the cache.

Since you could attach the drive to a windows computer and repair it, I assume it’s using one of the windows formats instead of a Mac format. That is likely why disk utility cannot repair it. There is limited support for windows formats.

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Why am I unable to repair an external SSD in disk utility after improper ejection?

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