Existing drive became unmountable when I replaced another

[idean]

Background: all the drives have been plugged in for days. The old Disk 1 (6TB) was replaced in the interface with a newish pre-cleared 14TB drive. To do this, I stopped the array, selected the 14TB drive in "Disk 1", and re-started the array.

 

When it started, it started rebuilding the array... sorta. Instead of putting the new drive in slot it seems to have put it in Drive 2 and moved old Drive 2 to Drive 1?? I'm not 100% sure about that, my short-term memory looking at serial numbers is not what it was. I just know that now I have it rebuilding Disk 1 (like it should) but Disk 2 is "Unmountable", which I expected Disk 1 to be, since I haven't yet formatted it.

 

What should I do? Wait for this to rebuild before I format Disk 2?  (Good thing I have dual parity??)

 

Lesson learned: screenshots before and after any change so that I know exactly what serial numbers I'm dealing with and don't have to rely on my short term memory more than 5 minutes.

 

unraid-diagnostics-20240325-0938.zip

Edited March 25 by idean
Added screenshot

[JorgeB]

36 minutes ago, idean said:

Instead of putting the new drive in slot it seems to have put it in Drive 2 and moved old Drive 2 to Drive 1?? I'm not 100% sure about that

I don't see anything that suggests that, I see that disk2 was replaced before and apparently successfully rebuilt, though logs show ATA errors for multiple disks, so you should check power/connections, at least for the affected ones.

 

As for disk2, once the rebuild finishes, unassign it and start the array, if the partition is the issue, doing that will recreate it, and if it looks good, then rebuild on top.

 

 

[trurl]

1 hour ago, idean said:

I expected Disk 1 to be, since I haven't yet formatted it.

Don't even think of that word.

 

Format is NEVER part of rebuild.

 

Format is a write operation. It writes an empty filesystem to the disk. If you format a disk in the array, Unraid treats that write operation just as it does any other, by updating parity. So after formatting a disk in the array, the only thing that can be rebuilt is an empty filesystem.

[idean]

22 minutes ago, trurl said:

Don't even think of that word.

 

Format is NEVER part of rebuild.

 

Format is a write operation. It writes an empty filesystem to the disk. If you format a disk in the array, Unraid treats that write operation just as it does any other, by updating parity. So after formatting a disk in the array, the only thing that can be rebuilt is an empty filesystem.

Ah, it only asks you to reformat when adding a drive then? Not when replacing? Good to know (if I got that right)!

[trurl]

When you add a disk to a new slot in an array that already has valid parity, Unraid will clear the disk unless it has been precleared so parity will remain valid. All those zeros on a clear disk has no effect on parity. This is the only scenario where Unraid requires a clear disk. After the disk has been cleared and added to the array, you can format it so it can be used for files.

 

A disk that hasn't yet been formatted will appear as unmountable. In Main - Array Operation, it will list all unmountable disks and give you a checkbox to enable the format button and allow you to format them. You can see this in the screenshot you posted above.

 

NEVER format a disk that should contain your data. An unmountable disk that should have data on it needs to have its filesystem repaired. That is what check filesystem is for. Or, as suggested above, maybe its partition needs to be fixed.

 

1 hour ago, JorgeB said:

As for disk2, once the rebuild finishes, unassign it and start the array, if the partition is the issue, doing that will recreate it, and if it looks good, then rebuild on top.

DO NOT FORMAT!!!

[idean]

All good now after a reboot... the "Unmountable" drive mounted right up! The drive I replaced is rebuilding, as expected. And I found an email from unRaid saying that the preclear on it completed last week, so the whole disk swap thing was a false alarm. Phew!  It was just scary that the disk logically next to the one I replaced was now unmountable.

 

It's scary that it this happened as I was replacing a drive. Was it due to the encryption key being missing from /root due to some sort of race condition?

 

I use the webGui "events":

# auto unlock array
install -D /boot/custom/bin/fetch_key /usr/local/emhttp/webGui/event/starting/fetch_key
install -D /boot/custom/bin/delete_key /usr/local/emhttp/webGui/event/started/delete_key
install -D /boot/custom/bin/fetch_key /usr/local/emhttp/webGui/event/stopped/fetch_key

 

My biggest lesson learned: Lots of screenshots and notes before and after system changes on unRaid. My memory in regards to serial numbers is totally unreliable.

[JorgeB]

11 minutes ago, idean said:

All good now after a reboot...

This suggests there could be an intermittent issue with the disk/controller, a reboot by itself should never resolve an "invalid partition" error.