Veritas Volume Manager 5.0 Release Notes (5900-0593, March 2010)

Veritas Volume Manager 5.0 Release Notes
New Features in VxVM 5.0
Chapter 1 9
NOTE The SCSI 3 PR enhancements are not available with Base-VxVM and Full
VxVM bundles.To enable this feature, an additional license is required.
• File-level SmartSync
The SmartSync feature of VxVM has been extended to support Oracle Resilvering of files
in Veritas File System.
• Enhancements to DMP
There are a several enhancements to the Dynamic Multipathing (DMP) feature:
— Faster failure detection and recovery by DMP
DMP has been enhanced to allow the vxdmpadm command to be used to adjust the I/O
error recovery and I/O throttling mechanisms on individual paths.
— Changing DMP tunables
The values of most DMP tunables can now be set by using the vxdmpadm settune
command.
— Retry period for Persistent Group Reservation (PGR)
The maximum time period for which DMP retries the SCSI-3 Persistent Reserve
operation with A/P arrays can now be tuned by using the dmp_retry_timeout
parameter with the vxdmpadm command.
The default value is 120 seconds, which is twice the value of the SCSI I/O timeout.
This parameter has no direct effect on I/O processing by DMP. Disabling a switch port
can trigger a fabric reconfiguration, which can take time to stabilize. During this
period, attempting to register PGR keys through the secondary path to an array may
fail with an error condition, such as unit attention or device reset, or the return of
vendor-specific sense data. The retry period allows a fabric reconfiguration, which is
usually a transient condition, to not be seen as an error by DMP.
To display the current value of dmp_retry_timeout, type:
# vxdmpadm gettune dmp_retry_timeout
To change the value of dmp_retry_timeout, type:
# vxdmpadm settune dmp_retry_timeout=value
Do not set the value of the retry period too high.
This can delay the failover process, and result in I/O sluggishness or suppression of
I/O activity during the retry period.