Add and remove volumes in a consistency group

Contributors

If you want to change the composition of the consistency group by adding or removing a volume, you must first delete the original relationship and then create the consistency group again with the new composition.

This workflow applies to ONTAP 9.8 and 9.9. Beginning with ONTAP 9.10.1, it is recommended that you manage consistency groups through System Manager or with the ONTAP REST API.

About this task
  • The composition change is not allowed when the consistency group is in the “InSync” state.

  • The destination volume should be of type DP.

The new volume you add to expand the consistency group must have a pair of common Snapshot copies between the source and destination volumes.

Steps

This procedure assumes that there are two volume mappings: vol_src1 ←→ vol_dst1 and vol_src2 ←→ vol_dst2, in a consistency group relationship between the end points vs1_src:/cg/cg_src and vs1_dst:/cg/cg_dst.

  1. Verify that a common Snapshot copy exists between the source and destination volumes on both the source and destination cluster:

    source::>snapshot show -vserver vs1_src -volume vol_src3 -snapshot snapmirror*

    destination::>snapshot show -vserver vs1_dst -volume vol_dst3 -snapshot snapmirror*

  2. If no common Snapshot copy exists, create and initialize a FlexVol SnapMirror relationship:

    destination::>snapmirror initialize -source-path vs1_src:vol_src3 -destination-path vs1_dst:vol_dst3

  3. Delete the zero RTO consistency group relationship:

    destination::>snapmirror delete -destination-path vs1_dst:vol_dst3

  4. Release the source SnapMirror relationship and retain the common Snapshot copies:

    source::>snapmirror release -relationship-info-only true -destination-path vs1_dst:vol_dst3

  5. Unmap the LUNs and delete the existing consistency group relationship:

    destination::>lun mapping delete -vserver vs1_dst -path <lun_path> -igroup <igroup_name>
    NOTE: The destination LUNs are unmapped, while the LUNs on the primary copy continue to serve the host I/O.

    destination::>snapmirror delete -destination-path vs1_dst:/cg/cg_dst

    source::>snapmirror release -destination-path vs1_dst:/cg/cg_dst -relationship-info-only true

  6. Create the new consistency group with the new composition:

    destination::>snapmirror create -source-path vs1_src:/cg/cg_src -destination-path vs1_dst:/cg/cg_dst -cg-item-mappings vol_src1:@vol_dst1, vol_src2:@vol_dst2, vol_src3:@vol_dst3

  7. Resynchronize the zero RTO consistency group relationship to ensure it is in sync:

    destination::>snapmirror resync -destination-path vs1_dst:/cg/cg_dst

  8. Remap the LUNs that you unmapped in Step 5:

    destination::> lun map -vserver vs1_dst -path <lun_path> -igroup <igroup_name>

  9. Rescan host LUN I/O paths to restore all paths to the LUNs.