Read through the Unraid manual about how to replace a failed disk f.x. One of the steps in the procedure is to "replace the failed hard disk". Does this mean that it is mandatory for the new disk to use the same SATA cable ? or does this simply mean that the new disk has to use the same Disk number in the "Array Device list" ? Is the latter criteria enough ?

 

Just had one disk that became unmounted for what ever reason and I tried to use one of the hot spares I had in the server as "unassigned devices" (connected to a different SATA cable). At some point in time the server started to rebuild but the "new disk" still ended up after the re-build was finished as "disk not formatedd" so I had to format it. Lost ~3 TB of data that I had (and luckily could) recover from an external back-up.

 

From an Unraid perspective is there a difference between an "unmounted disk" and "failed disk" ? From a user perspective then I get equally desperate and do not know what to do or how to handle it.

 

Ran an extensive disk check of the disk in question and it turned out fine. Next step is to install it in the server again and run multiple disk-clear cycles and see what happens. Really not sure if the disk is really "failed".

 

Any feedback is highly appreciated.

Kind regards

C

From an Unraid perspective is there a difference between an "unmounted disk" and "failed disk" ? From a user perspective then I get equally desperate and do not know what to do or how to handle it.

 

These are two very different situations, unmountable disk is usually a file system problem and you need to use the appropriate file system repair tools (although it's possible the disk itself also has issues), a disable disk means a write failed to that disk, this can be a bad disk, controller, cable, etc.

 

Rebuilding an unmountable disk will never fix the file system issues.

What tools do you have in mind ?

https://lime-technology.com/wiki/index.php/Check_Disk_Filesystems

You said the disk had become "... unmounted, for whatever reason ..."  => Was it "unmounted" or had it been disabled (a red "X" on the display) ??

 

Those are two very different situation.  If it had in fact failed (red "X"), then you could simply rebuild it by assigning a different disk to that slot in the array => this disk can be on ANY controller in the system and use any SATA cable you want.

 

But if it was simply unmounted ("missing" or "unmounted" on the display), then UnRAID hasn't marked it as "failed" ... so something else is wrong.

 

From what you described, one possibility r.e. what happened is that the disk may have somehow been cleared -- which would result in it being unmounted ... but that disk was still parity protected (unfortunately it didn't have any data on it).  If you then did a rebuild of that disk, the rebuilt disk would still be unmounted (as you outlined).