HP 3PAR Apple OS X Implementation Guide

basis.
• When all queues are in use and a host HBA port tries to initiate I/O, it receives a target queue
full response from the HP 3PAR StoreServ Storage port. This condition can result in erratic I/O
performance on each host. If this condition occurs, each host should be throttled so that it
cannot overrun the HP 3PAR StoreServ Storage port's queues when all hosts are delivering
their maximum number of I/O requests.
NOTE: When host ports can access multiple targets on fabric zones, the assigned target
number assigned by the host driver for each discovered target can change when the host is
booted and some targets are not present in the zone. This situation may change the device
node access point for devices during a host reboot. This issue can occur with any
fabric-connected storage, and is not specific to the HP 3PAR StoreServ Storage.
HP 3PAR Priority Optimization
The HP 3PAR Priority Optimization feature introduced in HP 3PAR OS 3.1.2. MU2 is a more
efficient and dynamic solution for managing server workloads and can be utilized as an alternative
to setting host I/O throttles. Using this feature, a storage administrator is able to share storage
resources more effectively by enforcing quality of service limits on the array. No special settings
are needed on the host side to obtain the benefit of priority optimization although certain per target
or per adapter throttle settings may need to be adjusted in rare cases. For complete details about
how to use HP 3PAR Priority Optimization (Quality of Service) on HP 3PAR StoreServ Storage
arrays, see the HP 3PAR Priority Optimization technical whitepaper, which is available on the HP
SC website:
HP 3PAR Priority Optimization
HP 3PAR OS Persistent Ports
The HP 3PAR OS Persistent Ports (or virtual ports) feature minimizes I/O disruption during an HP
3PAR StoreServ Storage online upgrade or node-down event (online upgrade, node reboot, or
cable pull test). Port shutdown or reset events do not trigger this feature.
Each FCFC target storage array port has a partner array port automatically assigned by the system.
Partner ports are assigned across array node pairs.
HP 3PAR OS Persistent Ports allows an HP 3PAR StoreServ Storage FCFC port to assume the identity
(port IP address) of a failed port while retaining its own identity. 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 withHP 3PAR OS Persistent Ports is transparent to most host-based
multipathing software, which can keep all of its I/O paths active.
NOTE: Use of HP 3PAR OS Persistent Ports technology does not negate the need for properly
installed, configured, and maintained host multipathing software.
For a more complete description of the HP 3PAR OS Persistent Ports feature, its operation, and a
complete list of required setup and connectivity guidelines, see:
• The HP Technical white paper HP 3PAR StoreServ Persistent Ports (HP document
#F4AA4-4545ENW)
This document is available on the following HP SC website:
HP Support Center
• The HP 3PAR Command Line Interface Administrator’s Manual, “Using Persistent Ports for
Nondisruptive Online Software Upgrades”
This document is available on the following HP SC website:
HP Support Center
10 Configuring the HP 3PAR StoreServ Storage for Fibre Channel