Thanks so much for your detailed answer.
To summerize the drive error management on unRAID with btrfs data drives :
- electrical, mechanical, electronical data/parity drive failures are detected and logged by unRAID : drive to be replaced
- limited bitrod error transparently corrected by drive firmware ECC
- heavy bitrod error, leading to read error, corrected by unRAID with parity rebuilt, which then try to write the data onto the failed drive
just logged as error if write completes, or disk is disalbled and emulated by unRAID until replaced
- btrfs metadata checksum error corrected by btrfs (default) metadata DUP attribute
- btrfs data checksum error (without data DUP) : error indicated and logged during scrub, data copy is prevented, backup process necessary
One more question regarding unRAID+btrfs :
> is to possible to run a double parity array and to use the second parity drive to fix any failed drive ( ideally remotely until the failed drive is actually replaced) :
- either use the second parity drive as a replacement data drive
- keep the remaining parity drive in case of failed parity drive
Is this a manual process ? can it be automated on unRAID ?