How can I re-add a "failed" drive without doing a data-rebuild, when I know for a fact the drive is fine?

[relink]

There must be some way to clear the failed status, and just simply add the drive back to the array?

 

I know the drives are fine, it's my SAS expander thats bad. I already have a new one on the way, but I am trying to keep Unraid up until it gets here. Normally the disks just show as missing, and I reboot a few times and I'm good to go. But now disks are randomly being marked as "Failed".

Whenever they are marked as failed the only way to get them back into the array seems to be to remove them, start the array in maintenance mode, stop the array, re-add the disk, then re-build the data on that drive. This would be fine if it wasn't multiple times a day when I know there's nothing wrong with the disks anyway. 

[JorgeB]

You can do a new config, but will then need to run a correcting parity check, and that will take the same time as a rebuild.

[JonathanM]

On 1/30/2024 at 7:09 PM, relink said:

now disks are randomly being marked as "Failed".

Remember, Unraid only "fails" a disk when a write error occurs. Sometimes that can happen when a read error happens, and Unraid automatically tries to write the emulated data that should be there, and the write fails, so yes, in that case the dropped drive data is fine. However, if it happens with a write command NOT the result of a failed read, that means the physical drive is guaranteed to be different than what is emulated in the array. If you throw away the emulated data in favor of what is on the physical drive, you lose the latest writes.

 

So, your choice is either to rebuild the data drive, or rebuild the parity drive. Either takes about the same amount of time, but rebuilding the data drive ensures that the latest writes are preserved.

[relink]

I appreciate the info, I'll keep it in mind though hopefully this doesn't happen again. Unfortunately I lost about 8TB worth of data because of this, no fault of Unraid, it was the HP SAS Expander I was using. In fact despite having 5 "failed" drives (which included both parity drives) Im really happy to see that a majority of my data is still intact thanks to Unraid! 

Luckily my Intel SAS expander came in today, and it's so far so good!