From the MCS

Complete the following steps from the MapR Control System to save volA/Cluster2's data on volA/Cluster1 and reestablish the original mirror relationship from volA/Cluster1 to volA/Cluster2.
  1. Stop writing new data to volA/Cluster2 by making this volume read-only:
    1. Click on the checkbox next to volA in the Volumes display.
    2. Click on the name of the volume to display the Volume Properties dialog.
    3. In the Volume Properties dialog, check the Read-only box and click OK.
  2. Make volA/Cluster1 a mirror of volA/Cluster2.
    1. Navigate to the node that is running the mapr-webserver service on Cluster1 to access the MCS.
    2. Select MapR-FS > Volumes from the navigation pane and click on the checkbox next to volA.
    3. From the Volume Actions tab, select Make Mirror Volume.
    4. Fill in the Source Volume name field (the source volume is volA in this example) and click OK.
  3. Start mirroring.
  4. Promote volA to a read-write volume.
    1. In the Mirror Volumes display, check the box next to volA.
    2. Click on the Volume Actions tab and select Make Standard Volume.
  5. Make volA/Cluster2 a mirror of volA/Cluster1.
    1. Navigate to the node that is running the mapr-webserver service on Cluster2 (where volA/Cluster2 resides) to access the MCS.
    2. In the Volumes display, check the box next to volA.
    3. Click on the Volume Actions tab and select Make Mirror Volume.