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 storage system network and disk operations.

Changing RAID data reconstruction speed

To change 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 storage system uses most of the system resources--CPU time, disks, and FC loop bandwidth (on FC-based storage systems)--available for RAID data reconstruction; this setting can heavily affect storage system performance. Low means that the storage system uses very little of the system resources; this setting lightly affects storage system performance. The default speed is medium. Note The setting for this option also controls the speed of Rapid RAID recovery.

Step

Action

Enter the following command:

options raid.reconstruct.perf_impact impact

impact can be high, medium, or low. High means that the storage system uses most of the system resources--CPU time, disks, and FC loop bandwidth (on FC-based storage systems)--available for RAID data reconstruction; this setting can heavily affect storage system performance. Low means that the storage system uses very little of the system resources; this setting lightly affects storage system performance. The default speed is medium.

Note
The setting for this option also controls the speed of Rapid RAID recovery.

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.