When a switchover is initiated, the interface shows a status of that command, shows the original Remote Copy Group go into a stopped state, the target-side Remote Copy Group named with a similar name then appears and shows that the switchover has completed. The switchover command is found under the Remote Copy Group within the interface and is found with all the other operations under the Actions menu for a Remote Copy Group. Initiating a switchover of a Peer Persistence Remote Copy Group is now an options within the SSMC interface. The administrator pre-defines the CPG for the remote array and enables the auto_failover and path_management policies to make a normal Remote Copy group into a Peer Persistent remote copy group. The auto-provisioning can be enabled on any Remote Copy group through the SSMC interface. The auto-provisioning will simplify the process and the chance for human error.
Previously, administrators performed this using the 3PAR Command Line Interface, and early adopters had to manually lookup and assign the WWN on the secondary array. When an administrator adds the volume it into a remote copy group, the group auto-provisions and assigns the same World Wide Name (WWN) to the target, secondary volume and that is required for Peer Persistence. This addition to SSMC brings a simple three step process for provisioning new Peer Persistence volumes in the management GUI: Create a new volume, add it to Remote Copy and then Export the volume from both arrays. Add a quorum witness server to the switchover magic and you have a ALUA allows the OS to recognize and redirect IO. At a high level, when a switchover command is issued, the path states change from active to standby and vice-versus. The source array provides open paths while the replication target shows its paths in standby. HP 3PAR Peer Persistence relies on operating systems which can use the ALUA command set of of the SCSI bus to recognize open and closed paths to a single volume. Peer Persistence is the HP branding for transparent LUN failover between storage arrays with no downtime – a concept VMware administrators will recognize is Metro Storage Clustering in the VMware vernacular.
With the 2.1 release of the HP 3PAR StoreServ Management Console, HP has enabled the creation and control of Peer Persistence configurations within the management tool.