Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Tuning VxVM
418 VERITAS Volume Manager Administrator’s Guide
volpagemod_max_memsz
The amount of memory, measured in kilobytes, that is allocated for caching FastResync
and cache object metadata. This tunable has a default value of 6144KB (6MB) of physical
memory.
Note The memory allocated for this cache is exclusively dedicated to it. It is not available
for other processes or applications.
Setting the value of volpagemod_max_memsz below 512KB fails if cache objects or
volumes that have been prepared for instant snapshot operations are present on the
system.
If you do not use the FastResync or DRL features that are implemented using a
version 20 DCO volume, the value of volpagemod_max_memsz can be set to 0.
However, if you subsequently decide to enable these features, you can use the
vxtune command to change the value to a more appropriate one:
# vxtune volpagemod_max_memsz value
where the new value is specified in kilobytes. Using the vxtune command to adjust
the value of volpagemod_max_memsz does not persist across system reboots
unless you also adjust the value that is configured in the /stand/system file.
volraid_minpool_sz
The initial amount of memory that is requested from the system by VxVM for RAID-5
operations. The maximum size of this memory pool is limited by the value of
voliomem_maxpool_sz.
The default value for this tunable is 16348 sectors (16MB).
volraid_rsrtransmax
The maximum number of transient reconstruct operations that can be performed in
parallel for RAID-5. A transient reconstruct operation is one that occurs on a
non-degraded RAID-5 volume that has not been predicted. Limiting the number of these
operations that can occur simultaneously removes the possibility of flooding the system
with many reconstruct operations, and so reduces the risk of causing memory starvation.
The default number of transient reconstruct operations that can be performed in parallel is
1.