You use mirror verification to ensure that the two plexes of a synchronous mirrored aggregate are identical. You can control the speed of mirror verification, and its effect on system resources, by using the raid.verify.perf_impact option.
When mirror verification and RAID-level scrubbing are running at the same time, Data ONTAP limits the combined resource utilization to the greatest impact set by either operation. For example, if raid.verify.perf_impact is set to medium and raid.scrub.perf_impact is set to low, the resource utilization of both operations has a medium impact.
For more information about synchronous mirroring, see the Clustered Data ONTAP Data Protection Tape Backup and Recovery Guide.
impact can be high, medium, or low.
high means that the storage system uses most of the system resources available for mirror verification; this setting can heavily affect storage system performance, but the mirror verification finishes sooner.
low means that the storage system uses very little of the system resources; this setting lightly affects storage system performance, but the mirror verification takes longer to complete.
The default impact is low.