I value my personal pictures so I store them on a home NAS which is running Solaris/ZFS. The server has two data disks mirrored. It's been running perfectly fine for the last two years but recently one of the disk drives returned corrupted data during ZFS scrub. If it wasn't for ZFS I probably wouldn't even know that some pixels are wrong... or perhaps that some pictures are missing... This is exactly why I've used ZFS on my home NAS.
# zpool status vault
pool: vault
state: ONLINE
status: One or more devices has experienced an unrecoverable error. An
attempt was made to correct the error. Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
using 'zpool clear' or replace the device with 'zpool replace'.
see: http://www.sun.com/msg/ZFS-8000-9P
scan: scrub repaired 256K in 3h54m with 0 errors on Tue Mar 11 17:34:22 2014
config:
NAME STATE READ WRITE CKSUM
vault ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
c4t1d0 ONLINE 0 0 2
c5t0d0 ONLINE 0 0 0
errors: No known data errors
So does ZFS fix the bad data by writing it to a new sector on the mirror disk, or does it just re-write it in-place?
ReplyDeleteIf it's re-written in-place, does anything check the previous data location for the presence of bad sectors?