On Sat, Dec 10, 2022 at 10:06:34AM -0300, Carlos Carvalho wrote:

Certainly we have. Currently admins have to periodically run full block range
checks in redundant arrays to detect bad blocks and correct them while
redundancy is available. Otherwise when a disk fails and you try to reconstruct
the replacement you hit another block in the remaining disks that's bad and you
cannot complete the reconstruction and have data loss. These checks are a
burden because they have HIGH overhead, significantly reducing bandwidth for
the normal use of the array.

If there was a standard interface for getting the list of bad blocks that the
firmware secretly knows the kernel could implement the repair continuosly, with
logs etc. That'd really be a relief for admins and, specially, users.

Both SCSI and NVMe can do this through the GET LBA STATUS command -
in SCSI this was a later addition abusing the command, and in NVMe
only the abuse survived.  NVMe also has a log page an AEN associated
for it, I'd have to spend more time reading SBC to remember if SCSI
also has a notification mechanism of some sort.