root@NAS:~ # zpool status -v NAS
pool: NAS
state: ONLINE
status: One or more devices has experienced an error resulting in data
corruption. Applications may be affected.
action: Restore the file in question if possible. Otherwise restore the
entire pool from backup.
see: http://illumos.org/msg/ZFS-8000-8A
scan: resilvered 2.37T in 0 days 08:34:58 with 9 errors on Fri Jul 27 20:40:32 2018
config:
NAME STATE READ WRITE CKSUM
NAS ONLINE 0 0 9
mirror-0 ONLINE 0 0 18
gptid/64c55dff-ebb9-11e5-812c-001fd08e5c4f ONLINE 0 0 18
gptid/029bf372-4e21-11e8-af61-001fd08e5c4f ONLINE 0 0 18
errors: Permanent errors have been detected in the following files:
/mnt/NAS/Media/Series/VO/13 Reasons Why/Saison 1/13.Reasons.Why.S01E01.mkv
Strange. There is a data error there, but it's in a file, not in the pool metadata. Can you delete that file and run a scrub? That might clear out the pool errors and allow you to detach the disk.
Yes it did ! I was able to offline and detach the faulty drive so now it's out of the NAS and I've got a single stripe pool again. Thanks a lot for your help.