Controlling the speed of plex resynchronization

What plex resynchronization is

Plex resynchronization refers to the process of synchronizing the data of the two plexes of a mirrored aggregate. When plexes are synchronized, the data on each plex is identical. When plexes are unsynchronized, one plex contains data that is more up to date than that of the other plex. Plex resynchronization updates the out-of-date plex until both plexes are identical.

When plex resynchronization occurs

Data ONTAP resynchronizes the two plexes of a mirrored aggregate if one of the following occurs:

One of the plexes was taken offline and then brought online later
You add a plex to an unmirrored aggregate

Changing plex resynchronization speed

To change the speed of plex resynchronization, complete the following step.

Step	Action
1	Enter the following command: options raid.resync.perf_impact impact impact can be `high`, `medium (default)`, or `low`. High means that the storage system uses most of the available system resources for plex resynchronization; 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.

Step

Action

Enter the following command:

options raid.resync.perf_impact impact

impact can be high, medium (default), or low.

High means that the storage system uses most of the available system resources for plex resynchronization; 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.

RAID operations affecting plex resynchronization speed

When plex resynchronization and RAID data reconstruction 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 by both operations has a medium impact.