macOS (11.4) 'forgets' continuously to mount external SSD

[Widlarizer]

Hi folks,

I'm using a Mac Pro 6,1 with Big Sur running on it. I've connected an Apple 256GB SSD in an OWC USB 3.0 to my Mac and it seems like that macOS is not able to mount this external SSD after a reboot.

So let's say that I formatted the external SSD with APFS or exFAT (in fact, it doesn't make any difference) and dropped some files on it.

After the next reboot, all files are gone and the SSD is just empty like it was right after formatting it.

After the second reboot, the external SSD does not show up in Finder any more. The disk utility tool shows the name of the case (OWC Envoy Media) and a container (Container disk4).

If I want to get access to the SSD again, I have to restart the formatting process

Please can you give me some advice how to fix this problem?

Many thanks in advance!

 

[rehkram]

What happens if you unmount the disk before restarting?

 

[Slartibart]

Assuming that the SSD was formatted wit a GUID partition scheme*.

open a Terminal and type and execute:

$ diskutil list |grep Name-of-your-SSD

there will be some output in the terminal like:

2: Apple_HFS Name-of-your-SSD 255.4 GB disk1s2

To mount the Drive use:

diskutil mount /dev/disk1s2

in the terminal.


*nota bene:

• Open Disk Utility
• Choose "Show All Devices" from the View menu
• Select the destination drive hardware (above the existing volume)
• Click Erase
• Choose the "GUID" partition scheme (2nd pop-up), THEN "APFS" formatting (1st pop-up) and name appropriately
• Click Erase

EDIT: Did you check wether your SSD can be founded under /Volumes folder? Open Finder -> Go -> Go to folder /Volumes (shortcut SHIFT + CMD + G)

 

[Widlarizer]

What happens if you unmount the disk before restarting?

Then the external SSD gets mounted after restart but all folders copied on it beforehand are not accessible anymore. Once I click on them nothing happens and I can't see the contents.

diskutil mount /dev/disk1s2

Alright, I did exactly what you told me to do and also made sure that the SSD can be found under /Volumes.

What is confusing me right now is the output in terminal after executing:

$ diskutil list |grep ExtSSD

The output was:

 1:   APFS Volume ⁨ExtSSD⁩    827.4 KB   disk4s1

Why does it show 827.4KB only? 🤔

 

[Widlarizer]

Update:
After a couple of restarts the external SSD seems to work fine until now. Let's cross fingers.

Thank you guys and I'll keep you posted!

 

[Widlarizer]

Hi guys,

I just checked how the external SSD is doing after copying a virtual machine (ova) on it a couple of hours ago.
All folders are still accessible but the ova file seems to be kind of "damaged", please check the attached screenshot.

 

[Widlarizer]

Alright, that's it...the SSD vanished again right after booting.

I think that either the OWC case or the SSD are done. Disk utility tells me that the SSD is not activated, but if I'm trying to activate it, all I get is an error message (com.apple.DiskManagement.disenter error 49218).

It really sucks