Dell Storage Manager 2020 R1 Administrator's Guide

Phase 2 — Cluster A fails and clients request failover to target Cluster B

If Cluster A stops responding because of an unexpected failure, fail over to Cluster B.

1. From Cluster B, promote the target volumes in Cluster B. This transforms the original target volumes (B1, B2, .. Bn) to standalone NAS volumes and makes them writable.
2. Delete the replication policies for the original source volumes (A1, A2, .., An).
3. Apply the source volume configuration from the original source volumes in Cluster A to the target volumes in Cluster B.
4. Restore the users and groups configuration from Cluster A. This restores the Cluster B users and groups to Cluster A settings.
5. Ensure that Cluster B is used to temporarily serve client requests during the failover time.
   1. Choose one of the following options:
      • IP address-based failovers: Change the IP addresses for Cluster B to match the IP addresses used by Cluster A. Existing client connections might break and might need to be re-established.
      • DNS-based failovers: Point the DNS names from your DNS server to Cluster B instead of Cluster A.

        Ensure that the DNS server on Cluster B is the same as the DNS server or in the same DNS farm as the DNS server of Cluster A. Existing client connections might break and might need to be re-established. You must unmount and re-mount the NFS exports on the clients.

   2. (Single NAS volume failovers) Manually update the DNS entry for the NAS volume that was failed over. This redirects clients that are accessing this volume from Cluster A to Cluster B, while other clients keep accessing other volumes using the same DNS name. Client systems might need to refresh their DNS cache.
   3. (Single NAS volume failovers) To force SMB and NFS clients to Cluster B, you must delete the SMB shares and NFS exports on Cluster A. This forces the SMB and NFS clients to reconnect, at such time they are connected to Cluster B. After restoring the source volume’s configuration on Cluster B, all of the SMB shares and NFS exports will be present on the target volume (on Cluster B), so no SMB share/NFS export configuration information is lost.

      The failed over volume can now be accessed using the exact same DNS name and SMB share/NFS export name as it was when hosted on Cluster A, except now it is hosted on Cluster B.

   4. Join Cluster B to the AD server or LDAP/NIS.

      Ensure that the AD server and LDAP server are in the same AD/LDAP farm or same server.