the return of "Unaligned write command" errors #10094
Description
Reporting an unusual situation. Have ZFS mirror array across two 1TB SSDs. It regularly spews "Unaligned write command" errors. From reading reports here and elsewhere, this problem used to exist, was fixed years ago, not supposed to happen today. So, a puzzle.
It turns out that the two SSDs report different physical sector size, one reports 512 bytes, one reports 4096 bytes. Same vendor, same model, same firmware. (WTH?!?)
zpool reports default ashift 0 (autodetect_.
zdb reports ashift 12 (correct for 4096 sectors)
So everything seems to be correct, but the errors are there.
The "unaligned write command" errors only some from the "4096 bytes" SSD. After these write errors, "zpool scrub" runs without errors ("repaired 0B"). Two other zfs mirror pools on the same machine run without errors (2x10TB and 2x6TB disks, all report 4096 physical sector size).
K.O.