I tried to erase and reformat an external SSD disk and received the following error message:
Unmounting disk
The volume âSSD 2TBâ on disk5s1 couldnât be unmounted because it is in use by process 18228 (mdworker_shared)
Couldnât unmount disk. : (-69888)
I need to reformat this disk but don't understand what is wrong.
Mac mini, macOS 14.2
Thank you very much Matti for taking time out to provide an answer for me. I did play around with Disk Utility options and found that changing the View from Show only Volumes to Show all Devices enabled me to Erase and Reformat this drive.
I was able to perform the reformatting by changing the View from Show only Volumes to Show All Devices.
So I don't need the help after all. Sorry if my post has inconvenienced anyone.
Nowadays occasionally the 1st reformat fails obviously because Disk Utility is too impatient and times out while waiting for some process accessing the device to terminate. But right after that the 2nd identical reformat usually succeeds.
No bother, it happens to us all.
BTW, the error message indicated that Spotlight was indexing the drive (mdworker) and would not release it which unfortunately is more common than it should be. It can also occur with other apps including the Finder...even when the Finder no longer viewing an item on that drive.
Also, erasing the whole physical drive as you probably did is what I prefer to do for external drives so that the partition table is also recreated. This can be especially important for retail external drives which can sometimes have some hidden partitions on them from the factory.
Good job discovering the solution!
Erasing "SSD 2TB" and creating "SSD 2TB"
