HP 3PAR X9000 File Serving Software (IBRIX) Implementation Guide (QL226-96987, June 2013)

on Fibre Channel target ports that connect to Fibre Channel fabric and are in point-to-point mode
where both the active and partner ports share the same fabric.
Each Fibre Channel port has a partner port automatically assigned by the system. Where a given
physical port assumes the identity of its partner port, the assumed port is designated as a persistent
port. Array port failover and failback with Persistent Ports is transparent to most host-based
multipathing software which, in most cases, can keep all its I/O paths active.
The Persistent Ports feature is activated by default during node-down events (online upgrade or
node reboot). Port shutdown or reset events do not trigger this feature. Persistent Ports is enabled
by default starting with the HP 3PAR OS 3.1.2 software.
In the event that an HP 3PAR Storage node is downed during an online upgrade or node-down
event, the Fibre Channel target ports fail over to their partner ports. For example, in a two-node
HP 3PAR Storage array configuration, if ports 0:1:1, 0:5:1 and 1:1:1, 1:5:1 are connected to
the fabric, then if node 0 goes down, ports 0:1:1, 0:5:1 fail over to ports 1:1:1, 1:5:1 and become
active while ports 1:1:1, 1:5:1 remain active.
In HP 3PAR Storage arrays with more than two nodes, failover behavior occurs on node pairs;
that is, if node 0 goes down, ports on node 0 fail over to node 1, if node 2 goes down, ports on
node 2 fail over to node 3, and so on. Conversely, when node 1 goes down, ports on node 1 fail
over to node 0, and when node 3 goes down, ports on node 3 fail over to node 2. When the
downed node is up again, the failed-over ports automatically fail back to their original ports.
During the failover and failback process, a short pause in I/O could be experienced by the host.
Persistent Ports Setup and Connectivity Guidelines
For Persistent Ports to function properly, specific cabling setup and connectivity guidelines that
need to be followed can be found in the HP 3PAR Command Line Interface Administrator’s Manual,
“Using Persistent Ports for Nondisruptive Online Software Upgrades.” See this document for other
information about Persistent Ports as well.
The fabric switch ports connecting to the HP 3PAR array ports must support NPIV and have the
feature enabled in order for Persistent Ports to work.
The showport command output includes Partner and FailoverState columns that display
the partner port <node>:<slot>:<port> information and failover state information, respectively.
FailoverState values represent the failover state of the two ports listed in the N:S:P and
Partner columns. The FailoverState value can be one of the following:
• none: No failover in operation
• failover_pending: In the process of failing over to partner
• failed_over: Failed over to partner
• active: The partner port is failed over to this port
• active_down: The partner port is failed over to this port, but this port is down
• failback_pending: In the process of failing back from partner
Use the showport HP 3PAR CLI commands to get the state of the persistent ports. In the output of
the showport command shown below, under the Partner column, port 1:1:1 is the partner port
that 0:1:1 would fail over to and 0:1:1 is the partner port to which 1:1:1 would fail over. When
Persistent Ports is not active, the FailoverState for the ports would indicate none.
Setting Up and Zoning the Fabric 11