HP StorageWorks Enterprise Virtual Array Online Firmware Upgrade Best Practices (5697-6388, January 2007)

IBM AIX
Checking or changing timeouts
AIX requires the disk settings shown in Table 3 for the native multipath d rives.
Table 3 IBM AIX timeout set tin gs
Setting
Value
Description
PR_key_value
NA
Sets the key value for persistent reservations. Persistent reservations
are not supported.
Algorithm
fail_over Sets the load balancing algorithm to fail_over. All I/O uses a
single path. The remaining paths are in standby m ode. The value
round_robin is not supported.
hcheck_interval
60
Sets the path health feature to check each device every 60 seconds.
hcheck_mode
nonactive
Specifies the I/O paths monitored by the path health checking
feature: nonactive—Checks all I/O paths for Failed status, and
checks standby paths for Used/Opened devices.
queue_depth
8
Sets th e queue depth.
reserve_policy single path Sets th e reserve policy to standard SCSI-2 reservations.
rw_timeout
60
Sets the read/write timeout to 60 seconds.
Managing application I/O timeouts
Applications are typically insulated from the online controller firmware upgrade by the operating system
and HBA driver software. Consequently, if the application is running on a properly configured operating
system, the online controller upgrades will be per formed successfully.
It may be necessary to determine if any applications have timeout requirements that are more stringent
than those of the operating system. Any applications with more stringent timeouts should be evaluated
to determine if the application timeous will be exceeded by the resync interval that occurs during the
online upgrade.
Extensive testing has been done to evaluate the impact of an online upgrade on the following applications:
• Oracle 10g
• Microsoft Exc hange 2003
• Microsoft SQL Server 2005
Under both light and heavy I/O loads, these applications reported no errors of any kind during the online
firmware upgrade. The app lications did not fail du ring the upgrade and returned to normal operation
immediately following completion of the upgrade. However, there was an impact on performance. To
minimize the performance impact on users, the online upgrade should be performed during a period of
low user activity
For detailed testing results, see " Effect of online firmware upgrade on application resiliency" on page 27.
16
Evaluating the SAN for an online upgrade