VERITAS Volume Manager 4.1 Release Notes (5900-0591, March 2010)

VERITAS Volume Manager 4.1 Release Notes
New Features in VERITAS Volume Manager 4.1
Chapter 1 11
• Dynamic LUN Expansion
Previous releases of VXVM did not allow you to take advantage of a change in the size of a
disk once the disk had been initialized; any attempt to do so would result in loss of data.
However, in this release, Dynamic LUN capability allows you to resize the device while
preserving the existing data.
• Unique Number for Messages
To enable easy identification of messages, each message contains a unique identifier.
Using this ID number when reporting messages to HP support will enable them to
respond more easily to customer requests.
• Dynamic Multipathing Enhancements
— Coexistence of DMP with Third Party Drivers
— Failback is now a cluster-wide operation that provides significant performance i
mprovements.
— A/PF type arrays are now supported by DMP in a clustered environment.
— Support for B_FAILFAST flag
DMP supports the B_FAILFAST flag if the underlying device driver exports the
ddi-failfast-supported property. The B_FAILFAST flag allows the disk drivers to
avoid heroic, time-consuming retry behavior when it is not required or is
inappropriate. The B_FAILFAST flag is intended to allow modified error recovery
behavior in the disk driver when no communication can be established with the
device. However it does not dictate specific retry behavior, nor does it imply or
guarantee deterministic failure times.
When I/O is requested to a device associated with the ddi-failfast supported
property, and the device has multiple paths available or I/O request is for a Read
operation from a volume that has an alternate source (mirror), DMP will set the
B_FAILFAST flag in the I/O request. While DMP sets the B_FAILFAST flag, DMP has
no knowledge of whether the underlying disk driver’s behavior is influenced by
B_FAILFAST.
— Coexistence of DMP with Third Party Drivers
With this release, the generic framework within the Device Discovery Layer (DDL)
enables DMP to coexist with other third party multi-pathing drivers such as EMC
PowerPath.
— Performance improvements have been made to DMP.
• Instant Snapshots