Comparing the plexes of mirrored volumes

When you should compare plexes

Because the plexes of mirrored volumes are almost never unsynchronized, you rarely need to compare the plexes of a mirrored volume. If you do need to compare the plexes of a mirrored volume, Data ONTAP enables you to do the following tasks:

Compare plexes
Note
Comparing plexes might affect filer performance.
Stop comparing plexes
Suspend and resume comparing plexes
View the progress of the comparison

Comparing plexes

The mirrored volume must be online before you can compare the plexes. When comparing the two plexes of a mirrored volume, you can choose one of the following options:

Data ONTAP compares plexes and corrects differences it finds. Network Appliance recommends this option.
Data ONTAP compares plexes but you specify that it should not correct differences. If you choose this option, you must determine which plex is the good one and synchronize the other plex to it. The process to determine the good plex can be difficult and can use advanced Data ONTAP commands. You must consult with Network Appliance Technical Support before correcting differences using this option.

To compare the two plexes of a mirrored volume, complete the following steps.

Step	Action
1	If you...	Then...
Want Data ONTAP to correct differences	Enter the following command: vol verify start volname volname is the name of the mirrored volume whose plexes you are comparing. If no volname is specified, the plexes of all online mirrored volumes are compared.
Do not want Data ONTAP to correct differences	Enter the following command: *vol verify start volname* -n** If volname is not specified, Data ONTAP compares the plexes of a mirrored volume for all volumes.

Step

Action

If you...

Then...

Want Data ONTAP to correct differences

Enter the following command:

vol verify start volname

volname is the name of the mirrored volume whose plexes you are comparing. If no volname is specified, the plexes of all online mirrored volumes are compared.

Do not want Data ONTAP to correct differences

Enter the following command:

vol verify start volname -n

If volname is not specified, Data ONTAP compares the plexes of a mirrored volume for all volumes.

Stopping plex comparison

You might need to stop Data ONTAP from comparing mirrored volume plexes. For example, you might stop verifying because it affects filer performance. To stop Data ONTAP from comparing plexes, complete the following step.

Step	Action
1	Enter the following command: vol verify stop volname If volname is not specified, Data ONTAP stops comparing plexes for all volumes.

Suspending and resuming plex comparison

Rather than stopping Data ONTAP from comparing the plexes of a mirrored volume, you can suspend comparing plexes. The comparison remains suspended until you resume it, stop it, or reboot the filer.

To suspend or resume a comparison of plexes, complete the following step.

Step	Action
1	If you want to...	Then...
Suspend the comparison	Enter the following command: vol verify suspend volname If volname is not specified, Data ONTAP suspends comparing plexes for all volumes.
Resume the comparison	Enter the following command: vol verify resume volname If volname is not specified, Data ONTAP resumes comparing plexes for all volumes.

Step

Action

If you want to...

Then...

Suspend the comparison

Enter the following command:

vol verify suspend volname

If volname is not specified, Data ONTAP suspends comparing plexes for all volumes.

Resume the comparison

Enter the following command:

vol verify resume volname

If volname is not specified, Data ONTAP resumes comparing plexes for all volumes.

Viewing the status of a plex comparison

Plex comparison status tells you what percentage of the plex comparison has been completed. Plex comparison status also displays whether plex comparison of a mirrored volume is suspended.

To view the status of a plex comparison, complete the following step.

Step	Action
1	Enter the following command: vol verify status volname If volname is not specified, Data ONTAP shows the status of all volumes whose plexes are currently being compared.