Controlling the speed of RAID data reconstruction

About RAID data reconstruction

If a disk fails, the data on it is reconstructed on a hot spare disk if one is available. Because RAID data reconstruction consumes CPU resources, increasing the speed of data reconstruction sometimes slows filer network and disk operations.

Modifying RAID data reconstruction speed

To modify the speed of data reconstruction, complete the following step.

Step	Action
1	Enter the following command: options raid.reconstruct.perf_impact impact impact can be high, medium, or low. High means that the filer uses most of the CPU time available for RAID data reconstruction; this setting can heavily affect filer performance. Low means that the filer uses very little CPU time; this setting lightly affects filer performance. The default speed is medium.

Step

Action

Enter the following command:

options raid.reconstruct.perf_impact impact

impact can be high, medium, or low. High means that the filer uses most of the CPU time available for RAID data reconstruction; this setting can heavily affect filer performance. Low means that the filer uses very little CPU time; this setting lightly affects filer performance. The default speed is medium.

RAID operations affecting RAID data reconstruction speed

When RAID data reconstruction and plex resynchronization 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.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.