zfs i/o error, no driver error

[Andriy Gapon]

During recent zpool scrub one read error was detected and "128K repaired".
In system log I see the following message:
ZFS: vdev I/O failure, zpool=tank
path=/dev/gptid/536c6f78-e4f3-11de-b9f8-001cc08221ff offset=284456910848
size=131072 error=5

On the other hand, there are no other errors, nothing from geom, ahci, etc.
Why would that happen? What kind of error could this be?

Thanks!
-- 
Andriy Gapon