HP Tru64 UNIX and TruCluster Server Version 5.1B-6 Patch Summary and Release Notes

Performance of hwmgr Commands on Large System Configurations
On large system configurations, certain hwmgr commands may take a long time to run and can
produce voluminous output. For example:
• On a system connected to a large storage area network, the hwmgr -view devices
command can take a long time to begin displaying output, because it must first select devices
from all of the hardware components in the system and then retrieve, format, and sort the
output report.
• On a maximally configured AlphaServer GS1280 system with highly interconnected storage,
the hwmgr -view hierarchy command generates thousands of lines of output.
The output from these commands is gathered and sorted in memory before the report begins to
be displayed. In a system with hundreds or thousands of attached storage units, the processing
stage can take several minutes and you will not see any output during that time.
When using the command hwmgr -view devices -cluster, the time can be even longer
and the size of the report can be larger because in most clustered configurations, mass storage
devices are reported by every member and thus appear multiple times in the generated report.
Therefore, you may need to relax the memory limits for the process running the command,
because with such a large number of devices in the configuration, the system may be unable to
gather all of the data with the default memory limit.
We recommend that you run commands that generate large reports in the background (for
example, in a batch job) and save their output into a file or set of files for subsequent examination
or historical comparison.
LSM Spin Lock Issue
A patch in this kit addresses a spin lock issue in the LSM kernel that may occur under extremely
heavy I/O loads on multiprocessor systems.
To reduce the need for certain spin locks in the kernel I/O code, you can set a new sysconfigtab
variable, Max_LSM_IO_PERFORMANCE, to 1 (the default is 0). Doing this will increase LSM
I/O performance if it is found that performance is degraded because of a highly contentious spin
lock.
Note that using this spin lock performance feature reduces some of the debugging statistics that
are normally maintained.
In order to use this feature, you must allow at least one LSM I/O daemon (voliod). The voliod
daemon was changed to prevent the number of LSM kernel I/O daemons from being set to zero
if this spin lock performance feature is turned on.
The change to the following voliod command produces an error and the number of LSM kernel
I/O daemons remain unchanged:
# voliod -f set 0
lsm:voliod: ERROR: VOL_IO_DAEMON_SET failed: Permission denied
Possible Problem when Processing Many Command Parameters
When running commands or scripts that must process a large amount of command parameters,
your system may hang or you may see an error similar to this: /sbin/ls: arg list too
long.
If this occurs, try rerunning the command or script after entering the following command to
relax the command-line limits:
# sysconfig -r proc exec_disable_arg_limit=1
This kernel setting should not be used as a default. It should only be enabled when encountering
a problem where the exec() argument size limit has been approached.
You can also use the xargs command to break a long argument list into smaller lists. For more
information, see the xargs(1) reference page.
54 Tru64 UNIX Patches