Because RAID data reconstruction consumes CPU resources, increasing the speed of data reconstruction sometimes slows storage system network and disk operations. You can control the speed of data reconstruction with the raid.reconstruc.perf_impact option.
When RAID data reconstruction and plex resynchronization are running at the same time, Data ONTAP limits the combined resource utilization to the greater impact set by either operation. For example, if raid.resync.perf_impact is set to medium and raid.reconstruct.perf_impact is set to low, the resource utilization of both operations has a medium impact.
The setting for this option also controls the speed of Rapid RAID Recovery.
impact can be high, medium, or low.
high means that the storage system uses most of the system resources available for RAID data reconstruction; this setting can heavily affect storage system performance, but reconstruction finishes sooner, reducing the time that the RAID group is in degraded mode.
low means that the storage system uses very little of the system resources; this setting lightly affects storage system performance. However, reconstruction takes longer to complete, increasing the time that the storage system is running in degraded mode.
The default impact is medium.