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 Data ONTAP Data Protection Tape Backup and Recovery Guide for 7-Mode.