Technical white paper

HPE 3PAR StoreServ Persistent Ports

Executive summary

Mission-critical tier-1 storage environments require extreme high availability (HA). Tier-1 customers running hundreds (or thousands) of servers in an enterprise environment feel that a dependency on host multipathing failover software during firmware upgrades, node failures, or in response to a "loss_sync" event (a physical layer problem between the storage array and the switch) introduces the risk of a service disruption and hence should be avoided. HPE 3PAR Persistent Ports technology allows for a non-disruptive environment (from the host multi-pathing point of view) where host-based multi-pathing software will not be involved in maintaining server connectivity to the storage during firmware upgrades, in the event of a node failure, in response to an array port being taken offline administratively, or as the result of a hardware failure in the SAN fabric that results in the storage array losing physical connectivity to the fabric.
Persistent Ports technology does not negate the need for properly installed, configured, and maintained host multi-pathing software. Although Persistent Ports technology will isolate a server from the need for path failover during firmware upgrades, in the event of a fabric hardware failure resulting in a "loss_sync" or in the event a node becomes available due to a panic or loss of power, it will not protect from cable problems or host HBA failures that do not result in a "loss_sync" on the storage array node. A properly configured multi-pathing environment provides protection from these events.