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

Integrated support for Asymmetrical Active/Active arrays that comply to SPC-3 standards. This includes a new device attribute alua_enabled, and a new scsimgr command activate.
New load balancing policies for multi-pathed devices: closest_path, which selects an I/O path based on its affinity with the CPU issuing the I/O so as to minimize latency, and pref_tport, which preferentially selects an I/O path through a user-specified target port, useful when some target ports are optimized for I/O transfer to certain LUNs.
Ability to specify the preferred_path device attribute using the class and instance number of a lunpath. This is used with the preferred_path load balancing policy.
Increased maximum values for the path_fail_secs and transient_secs device attributes.

These changes are documented in the scsimgr(1M) and scsimgr_esdisk(7) manpages.

Impact

This release offers new options to manage multi-pathed disks and disk arrays.

Compatibility

There are no known compatibility issues.

Performance

There are no known performance issues.

Documentation

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

For details on new or modified commands, please check their associated man pages. In particular, the scsimgr(1M) and scsimgr_esdisk(7) manpages cover the new load balancing policy and scsimgr commands.

Obsolescence

There are no new obsolescence issues beyond those described for the February 2007 release of HP-UX 11i v3.