HP 3PAR HP-UX Implementation Guide

• The I/O queues are shared among the connected host server HBA ports on a first-come,
first-served 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 server. If this condition occurs, each host server should be throttled
so that it cannot overrun the HP 3PAR StoreServ Storage port's queues when all host servers
are delivering their maximum number of I/O requests.
NOTE: When host server 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 server 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 server 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 software introduced in HP 3PAR OS version 3.1.2.MU2 provides
an efficient and dynamic solution for managing server workloads and can be implemented as an
alternative to setting host server I/O throttling. Using this feature, a storage administrator can share
storage resources more effectively by enforcing quality of service limits on the array. No special
configuration is required on the host side to obtain the benefit of HP 3PAR Priority Optimization
software. In some cases, certain per target or per adapter throttle settings may need to be adjusted.
For complete details for using HP 3PAR Priority Optimization software with QoS on HP 3PAR
arrays, see the HP 3PAR Priority Optimization technical whitepaper available at:
HP 3PAR Priority Optimization
Operating System Specific Expected Behaviors
Upon reaching the upper limit for IOPS or bandwidth for a particular VVset and the target begins
to send Queue Full responses, all HP-UX hosts will report these responses as SCSI QUEUE FULL
messages with a cdb status (0x28)in the /var/adm/syslog/syslog.log file.
In addition to these SCSI messages, HP-UX 11i v2 hosts may report SCSI Async Write/Read Errors.
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 FC 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 features allow an HP 3PAR StoreServ Storage FC port to assume the
identity (WWN) of a failed port while retaining its own identity. When 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 HP 3PAR OS Persistent Port features is transparent to most host-based
multipathing software, which can keep all of its I/O paths active.
NOTE: Use of the HP 3PAR OS Persistent Ports features do 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 HP SC website:
12 Configuring the HP 3PAR StoreServ Storage for Fibre Channel