Checking and correcting parity

About checking RAID group parity

RAID group parity is checked by Data ONTAP by default. Data ONTAP also allows you to check RAID group parity manually.

You can check that parity is correct on RAID groups at the RAID group level, plex level, or volume level. Parity checking compares the data disks in a RAID group to the parity disk in a RAID group. If during the parity check Data ONTAP determines that parity is incorrect, Data ONTAP corrects the parity disk contents.

At the RAID group level, you can check only RAID groups that are in an active parity state. If the RAID group is in a degraded, reconstructing, or repairing state, Data ONTAP reports errors.

If you are checking a volume that has some RAID groups in an active parity state and some not in an active parity state, Data ONTAP checks and corrects the RAID groups in an active parity state and reports errors for the RAID groups not in an active parity state.

Checking parity on all volumes

To check parity on all volumes, complete the following step.

Step	Action
1	Enter the following command: vol scrub start

Checking parity on a specific volume, plex, or RAID group

To check parity on the RAID groups of a specific volume, plex, or RAID group, complete the following step.

Step	Action
1	Enter the following command: vol scrub start name name is the name of the volume, plex, or RAID group.

Examples

In this example, use the following command to check parity on all the RAID groups in the vol2 volume:

vol scrub start vol2

In this example, use the following command to check parity on all the RAID groups of plex1 of the vol2 volume:

vol scrub start vol2/plex1

In this example, use the following command to check parity on RAID group 0 of plex1 of the vol2 volume:

vol scrub start vol2/plex1/rg0

Stopping parity checking

You might need to stop Data ONTAP from checking parity. To stop parity checking, complete the following step.

Step	Action
1	Enter the following command: vol scrub stop name If name is not specified, Data ONTAP stops all parity checking.

Suspending and resuming parity checking

Rather than stopping Data ONTAP from checking and correcting parity, you can suspend checking for a while and resume checking later.

To suspend parity checking, complete the following step.

Step	Action
1	Enter the following command: vol scrub suspend name If name is not specified, Data ONTAP suspends all parity checking.

To resume parity checking, complete the following step.

Step	Action
1	Enter the following command: vol scrub resume name If name is not specified, Data ONTAP resumes all suspended parity checking.

Viewing parity checking status

The parity checking status tells you what percentage of the parity checking has been completed. Parity checking status also displays whether parity checking of a volume, plex, or RAID group is suspended.

To view the status of parity checking, complete the following step.

Step	Action
1	Enter the following command: vol scrub status name If name is not specified, Data ONTAP shows the parity checking status of all RAID groups.