Manage SnapMirror

To add a SnapMirror entry to the scheduler, complete the following steps:

1. In the Destination section, select a destination for this mirror. This can be either a volume or a qtree.
   
   a. Select a destination volume from the drop-down list in the Destination Volume field.

Note: The destination volume you select must be offline. If you attempt to use the root volume as the destination, you will receive an error. Either select a different destination volume or make another volume the root volume before selecting it for the destination volume.

b. Enter a full qtree pathname for the destination qtree to be used.

2. In the Source section, enter the source filer name for the mirror you want to replicate.

3. Enter the location name of the source mirror, either the volume name or the full qtree pathname.

4. In the Restart Mode field, select one of the options from the drop-down list. This option selects how you want to attempt to restart the transfer.
   
   Schedule Priority is the default setting.

5. In the Maximum Transfer Rate field (an optional field), enter a value, not lower than 11, to set a maximum transfer speed. 
   
   The default, not entering a value, causes the filer to transfer data as fast as the system allows.

6. In the Schedule section:

If you use the preset schedule:

a. Select how often a replication occurs from the drop-down list in the Repeat Mirror field.

b. Select when the replication occurs from the drop-down list in the Start Mirror On field.

If you use the custom schedule, enter a schedule in the following format:

minute hour dayofmonth dayofweek

7. Click Add.

To modify a SnapMirror entry to the scheduler, complete the following steps:

1. Click Modify for the entry that you want to change in the Manage SnapMirror page.
   
   Result: The Modify SnapMirror Entry page appears.

2. Make changes to the field or fields.

3. Click Apply.

You can view SnapMirror entries to display the following:

• Source filer and volume

• Destination filer and volume

• Settings

• Current transfer details

• Last transfer details

To view a SnapMirror entry, complete the following step.

1. Click View for the entry that you want to view in the Manage SnapMirror window.
   
   Result: The View SnapMirror page is displayed.

To delete a SnapMirror entry to the scheduler, complete the following steps:

1. Click Delete for the entry that you want to change in the Manage SnapMirror window.
   
   Result: A confirmation window is displayed.

2. Click OK.

To use the advanced SnapMirror management tasks, complete the following steps.

1. Click Advanced for the entry in the Manage SnapMirror page for which you want to perform advanced management operations.
   
   Result: The Manage SnapMirror, Advanced page is displayed.

2. Click one of the advanced SnapMirror options to perform that task.

If you need to take a snapshot of a SnapMirrored volume or qtree containing a database, you first need to prevent ongoing SnapMirror or other data transfers to the qtree or volume to avoid inconsistent data. You use quiesce in the Manage SnapMirror, Advanced page to block transfers.

What the quiesce command does  

Quiesce causes Data ONTAP to wait for all existing transfers to both volumes and qtrees to complete and blocks any further updates. If a qtree is not in a stable state (is in transition), then using quiesce forces it to move into a stable state.

You can quiesce only volumes and qtrees that are

• Online

• SnapMirror destinations

You cannot quiesce a restricted or offline volume or a qtree in a restricted or offline volume. Volumes and qtrees to be quiesced must be online SnapMirror destinations.

The snapmirror quiesce command stops a volume or qtree from acting as a SnapMirror destination but does not prevent it from acting as a SnapMirror source.

To temporarily block data transfers, complete the following steps.

1. Click Quiesce in the Managing SnapMirror, Advanced page.
   
   Result: A confirmation box is displayed.

2. Click OK.

3. Monitor the Status and State fields to verify that the volume is quiesced.

4. When the Status field indicates the volume is idle and the State field indicates the volume is quiesced, take the snapshot.

If you have stopped all transfers on a given volume or qtree using the snapmirror quiesce command and have performed the action for which you wanted the data consistent, you now want to restore the capability for scheduled or possible data transfer to this volume or qtree.

To resume SnapMirror transfers on a volume or qtree after a quiesce, complete the following steps.

1. Click Resume in the Manage SnapMirror, Advanced page for the volume or qtree on which you want to resume SnapMirror transfers.
   
   Result: A confirmation window is displayed.

2. Click OK to resume SnapMirror transfers.

You can abort a replication for a particular entry. For the abort feature to be available, the replication for the entry must be under way.

To abort a replication for a SnapMirror entry, complete the following steps:

1. Click Interrupt for the entry in the Manage SnapMirror, Advanced window.
   
   Result: A confirmation window is displayed.

2. Click OK.

You must perform a complete (baseline) transfer of information whenever you start up a SnapMirror source-destination relationship for the first time. This process is known as initializing a destination.

Note: The volume must be restricted before an initialize is performed.

To initialize a SnapMirror destination, complete the following step.

1. Click Initialize in the Manage SnapMirror Advanced page for the destination you want to initialize.
   
   Result: A confirmation window is displayed.

2. Click OK.

Ordinarily, SnapMirror updates the destination automatically according to the update schedule you specified. However, you can also initiate updates manually with the Update option in the Manage SnapMirror, Advanced window. 

You might need to run an unscheduled incremental SnapMirror update to prevent data loss resulting from a scheduled or threatened power outage or from a filer with a destination volume being taken offline for maintenance, repair, upgrade, or data migration.

To perform an unscheduled incremental update, complete the following step.

1. Click Update for the destination you want to update.
   
   Result: A confirmation window is displayed.

2. Click OK to update the destination.

You can break blocked SnapMirror transfers on a destination that is quiesced by using Break to automatically clear the quiesce condition.

To break quiesced SnapMirror transfers on a volume or qtree, complete the following steps.

1. Click Break in the Manage SnapMirror Advanced window.
   
   Result: A confirmation window is displayed

2. Click OK to clear the quiesced condition.

You might want to resynchronize a source and a destination volume or a qtree when

• You are changing the current source to a different volume or qtree.

• You make a destination volume writable for application testing and then want to make it a read-only destination again.

• You need to recover from a disaster that disabled the source.

• You want to reverse the functions of the source and the destination.

You can use Resync to put a volume or qtree back in the snapmirrored state and resynchronize its contents with the source without the initial transfer. When applied to the source volume, Resync can turn the source volume into a copy of the original destination volume. In this way, the roles of source and destination can be reversed.

Note: Resynchronizing requires that the two volumes or qtrees have at least one snapshot in common. You can resynchronize a volume to any other volume as long as both have at least one snapshot in common.

To resynchronize source and destination  volumes or qtrees, complete the following steps.

1. Click Resync.
   
   Result: A confimation window is displayed.

2. Click OK to resynchronize the volumes or qtrees.