How RAID-level disk scrubs verify data integrity

RAID-level scrubbing means checking the disk blocks of all disks in use in aggregates (or in a particular aggregate, plex, or RAID group) for media errors and parity consistency. If Data ONTAP finds media errors or inconsistencies, it uses RAID to reconstruct the data from other disks and rewrites the data.

RAID-level scrubs help improve data availability by uncovering and fixing media and checksum errors while the RAID group is in a normal state (for RAID-DP, RAID-level scrubs can also be performed when the RAID group has a single-disk failure).

RAID-level scrubs can be scheduled or run manually.

• How you schedule automatic RAID-level scrubs
  By default, Data ONTAP performs a weekly RAID-level scrub starting on Sunday at 1:00 a.m. for a duration of six hours. You can change the start time and duration of the weekly scrub, add more automatic scrubs, or disable the automatic scrub.
• How you run a manual RAID-level scrub
  You can manually run a RAID-level scrub on individual RAID groups, plexes, aggregates, or all aggregates using the aggr scrub command. You can also stop, suspend, and resume manual RAID-level scrubs.