Link Failure Between Sites A and B and Between Sites A and C

Fault Scenario

If the A-B and A-C links share a switch, failure of this switch will interrupt both links simultaneously. In other situations, network storms or bit errors may cause the links to fail successively.

DR Mechanism

• If the A-C link fails before the A-B link:
  1. When the A-C link fails, the Switchover Policy takes effect. When the Switchover Policy is Automatic, the Running Status of asynchronous remote replication between sites A and C changes to Standby, and that between sites B and C changes to Normal. When the Switchover Policy is Manual, select Manually Switch Over.
  2. After the A-B link fails, site A wins the arbitration and takes over services.

• If the A-B link fails before the A-C link:

  When the A-B link fails, either site A or site B may win the arbitration.

  • If site A wins, the Switchover Policy takes effect when the A-C link fails. When the Switchover Policy is Automatic, the Running Status of asynchronous remote replication between sites A and C changes to Standby, and that between sites B and C changes to Normal. In this case, services at site A are not protected.
  • If site B wins, the Switchover Policy takes effect when the A-C link fails. When the Switchover Policy is Automatic, the Running Status of asynchronous remote replication between sites A and C changes to Standby, and that between sites B and C changes to Normal. When the Switchover Policy is Manual, select Manually Switch Over. In this case, services at site B are protected.

Restoration

• If the A-C link fails before the A-B link:
  1. After the A-B and A-C links recover, the HyperMetro relationship between sites A and B is restored. The Recovery Policy of HyperMetro takes effect. If the Recovery Policy is Automatic, incremental data synchronization is automatically performed between sites A and B. If the Recovery Policy is Manual, click Synchronize manually. In this case, the relationships among the sites of the DR Star trio are as follows: HyperMetro between sites A and B, active asynchronous remote replication between sites B and C, and standby asynchronous remote replication between sites A and C.
  2. (Optional) Determine whether to set the asynchronous remote replication relationship between sites A and C to the active state. If this is required, choose More > Manually Switch Over on the DR Star Trios page.

• If the A-B link fails before the A-C link:
  • If site A wins the arbitration:

    After the A-B and A-C links recover, the HyperMetro relationship between sites A and B is restored. If asynchronous remote replication between sites B and C is in the active state and that between sites A and C is in the standby state, synchronize data between sites A and B. After the synchronization is complete, synchronize data between sites B and C. To restore the original network, choose More > Manually Switch Over on the DR Star Trios page. If asynchronous remote replication between sites A and C is in the active state and that between sites B and C is in the standby state, synchronize data between sites A and B, and between sites A and C.

  • If site B wins the arbitration:
    1. After the A-B and A-C links recover, the HyperMetro relationship between sites A and B is restored. The Recovery Policy of HyperMetro takes effect. If the Recovery Policy is Automatic, incremental data synchronization is automatically performed between sites A and B. If the Recovery Policy is Manual, click Synchronize manually. In this case, the relationships among the sites of the DR Star trio are as follows: HyperMetro between sites A and B, active asynchronous remote replication between sites B and C, and standby asynchronous remote replication between sites A and C.
    2. (Optional) Determine whether to set the asynchronous remote replication relationship between sites A and C to the active state. If this is required, choose More > Manually Switch Over on the DR Star Trios page.