Removing and reverting relationship from 3-site consistency group

If you are using Orchestrator 4.0, you can take an existing 3-site consistency group and remove 3-site relationships for both Metro Mirror or HyperSwap® configurations and revert them to stand-alone 2-site relationships. However, data that is replicated on the volumes on the system at auxiliary-far site is not deleted.

To remove a 3-site relationship from 3-site consistency group, you must ensure that the following condition is met:
  • The 3-site consistency group must not be in error and all three sites are reachable and online.
  • The 3-site consistency group state must be stopped.
  • Only one relationship can be removed and reverted at one time.
  • The partial state of 3-site consistency group is only supported in case of failure of addnewrelationship command or convertrcrelationship command or failure in removing relationship from 3-site consistency group to 2-site consistency group.
  • When 3-site consistency group moved to partial state on failure, the error should be fixed. The removal will resume only after fixing the error.

Using the management GUI

To remove and revert a 3-site relationship, complete these steps:
  1. Select Copy Services > Remote Copy.
  2. Under Partnerships, select the 3-site partnership in the left navigation.
  3. Verify that the 3-site consistency group that you want to revert to a 2-site relationship to is stopped. If it is not Stopped state, you must stop the 3-site consistency group. To stop the 3-site consistency group, select the consistency group and select Actions > Stop group. Wait for the consistency group state to change to stopped before proceeding.
  4. On the details page for the selected 3-site consistency group, right-click the 3-site relationship from the list of relationships displayed under Relationships and select Remove and Revert to 2-Site.
  5. Click Revert.
  6. Under Partnerships, select the 2-site partnership in the left navigation and select the Independent Relationships tab. Verify the reverted relationship is displayed in the list of independent relationships.

Using the command-line interface

To remove a 3-site relationship from 3-site consistency group, complete these steps:
  1. To stop the 3-site consistency group, enter the following command:
     [root@localhost home]# stop3sitercconsistgrp cg_1
    where cg_1 is the name of consistency group.
  2. To verify that the 3-site consistency group is stopped, enter the following command:
    # ls3sitercconsistgrp
 name state   primary periodic_copy_source sync_copy_state         periodic_copy_state freeze_time         cycle_period status
 cg_1 stopped Master  Master               consistent_synchronized idling              2021/11/21/15/19/51 300          online
  3. To remove the relationship from the 3-site consistency group and revert the relationship to an independent 2-site relationship, enter the following command:
    # convertrcrelationship -type 2site rcrel4
If the removal completes successfully, verify the removal of 3-site relationship by using ls3sitercrelationship command: 
# ls3sitercrelationship
 name   consistgrp master_vdisk_id auxnear_vdisk_id auxfar_vdisk_id sync_copy_progress periodic_copy_progress status
 rcrel0 cg_1       0               0                34                                                        complete
 rcrel1 cg_1       1               1                37                                                        complete
 rcrel2 cg_1       2               2                40                                                        complete
 rcrel3 cg_1       3               3                43                                                        complete

Orchestrator failure and recovery when removing and reverting relationships

In the case where the IBM Spectrum Virtualize 3-Site Orchestrator encounters a failure when a 2-site relationship is being removed from a 3-site consistency group, the following actions can be required:
  • If the orchestrator fails before removing a relationship from a 3-site consistency, ensure the following actions are taken:
    1. If the orchestrator fails and recovers to a stopped state, the periodic source is lost and the 3-site consistency group status can change to periodic_src_offline. If this occurs, you cannot remove the 2-site relationship. To remove a relationship, you must set the periodic source back to the online state by restarting the 3-site consistency group with the start3siteconsistgrp command. This action returns the periodic source back to its original state.
    2. After verifying that the periodic source is correct, ensure that the 3-site consistency group status is online.
    3. After status is online and orientation is set to default, you can remove relationship from the 3-site consistency group.
  • If the orchestrator recovery occurs during an attempt to remove a 2-site relationship, the following actions occur:
    1. The orchestrator recovery process cleans up the remaining 3-site consistency group objects during recovery.
    2. The remove relationship operation is automatically completed.
    3. The state of 3-site consistency group recovers to the stopped state.
  • If during orchestrator recovery the auxiliary-far site is offline, the 3-site consistency group recovers to the stopped state. After auxiliary-far site is available, the recovery operation restarts and the remove operation is automatically completed during recovery.
  • If the orchestrator recovery occurs after the remove relationship operation, the 3-site consistency group recovers its previous state before the recovery operation began.