HP Tru64 UNIX Release Notes for Version 5.1B-5 (AA-RVGEE-TE, March 2009)

1 New Features in Version 5.1B-5
The release notes in this chapter describe changes to the Tru64 UNIX kit for Version
5.1B-5. These include descriptions of key features, enhancements, and improvements
introduced in this kit.
1.1 Operating System Enhancements
The Tru64 UNIX Version 5.1B-5 release combines several resiliency enhancements and
the latest patch kit in the Version 5.1B-5 CD. The Version 5.1B-5 kit has undergone full
product qualification testing as a single entity on multiple configurations and is binary
compatible with all previous Version 5 stream releases.
The following sections provide information on some of the new functionality and
enhancements included in Tru64 UNIX Version 5.1B-5. For more information and a
complete list of the changes included in this release, see the Patch Summary and Release
Notes document, which is included on the Version 5.1B-5 CD and is available on the
Tru64 UNIX documentation website.
1.1.1 Performance Improvement for TCP Applications
The TCP selective acknowledgment feature is enabled by default. When the selective
acknowledgments feature is enabled, the data receiver informs the sender about all the
segments that were received successfully, so that the sender needs to retransmit only
those segments that were lost. This improves the performance of TCP applications on
a network which is experiencing packet loss.
1.1.2 Support for 2 TB LUNs
This kit enhances the Tru64 UNIX CAM subsystem to support a LUN size of up to 2
TB from the previous maximum limit of 1 TB. This allows Tru64 UNIX to take advantage
of the increased LUN size supported by the storage arrays.
1.1.3 Dynamic Pathing in Disk Driver
This kit enhances the CAM disk driver to dynamically recognize and use newly added
paths while the device is in use.
The new behavior will now dynamically recognize and use new paths while the device
is in use, thereby making all the paths available for I/O.
Before Version 5.1B-5, the disk driver used all paths that were available at open/mount
time. Paths added after would not be added to the active set until a close/open or
dismount/mount occurred.
1.1 Operating System Enhancements 9