Mass Storage Stack

The mass storage stack manages I/O devices, such as SCSI logical units (LUNs). In HP-UX 11i v3, it delivers functionality designed to enhance server scalability, adaptability, and performance.

Summary of Change

The March 2009 release includes the following enhancements to the mass storage stack:

Enhanced the mass storage stack to do target port congestion control
Added a fairness policy between regular I/O and high priority (internal) I/O
Allow the user to specify the actual lunpath to lockdown for the "path_lockdown" load balancing policy
Added new tunables to scsimgr for these enhancements

This release also includes defect fixes.

Impact

These defect fixes and enhancements improve server manageability, ease-of-use, and I/O performance.

Compatibility

There are no known compatibility issues.

Performance

SAN congestion events are minimized with target port congestion control. I/O timeouts can be reduced with the new fairness policy.

Documentation

For an overview of the Next Generation Mass Storage Stack, please see the white paper entitled “The Next Generation Mass Storage Stack,” available at http://docs.hp.com/en/netsys.html#Storage%20Area%20Management

For task-oriented information about managing mass storage, see HP-UX System Administrator's Guide: Storage Management at the same website.

For details on new or modified commands, please check their associated manpages. In particular, the scsimgr(1M) manpage covers the changes to scsimgr.

For details on defect fixes, see the patch documentation for the following patches:

PHCO_38603 11.31 scsimgr cumulative patch
PHKL_38604 11.31 esctl cumulative patch
PHKL_38605 11.31 esdisk cumulative patch

Obsolescence

No new obsolescence issues beyond those issued for the February 2007 release of HP-UX 11i v3.