Disk I/O errors on Adaptec ASR8805 raid controller

We have an Adaptec ASR8805 controller on one of the servers we manage. For various reasons we need to shrink a logical volume that is sitting on a RAID 6 logical device created and exposed by this controller, but we can’t because we’re getting seek errors:

Buffer I/O error on device dm-2, logical block 3330419721
sd 6:0:1:0: [sdb]  Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
sd 6:0:1:0: [sdb]  Sense Key : Hardware Error [current] 
sd 6:0:1:0: [sdb]  Add. Sense: Internal target failure
sd 6:0:1:0: [sdb] CDB: Read(16): 88 00 00 00 00 06 34 11 69 00 00 00 01 00 00 00
end_request: critical target error, dev sdb, sector 26643360000
sd 6:0:1:0: [sdb]  Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE

From what the controller is reporting, the RAID 6 is healthy, and all the physical drives SMART information seems ok(ish).

It turns out, no background checking of the RAID 6 parity has been enabled, and that is probably the problem, as reported by this article.

To get a “quick” fix (it’s a 24T array), I started:

# arcconf task start 1 logicaldrive 1 verify_fix

when it’ll be finished, I’ll enable the background check with:

# arcconf consistencycheck 1 on

I really hope this saves time to some fellow admin out there :)