Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Table 15-1
Kernel tunable parameters for VxVM (continued)
DescriptionParameter
The amount of memory, measured in kilobytes, that is
allocated for caching FastResync and cache object
metadata.
The default value is 65536k (64MB).
The memory allocated for this cache is exclusively
dedicated to it. It is not available for other processes
or applications.
Setting the value 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 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.
volpagemod_max_memsz
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 value is 1.
Increasing this size improves the initial performance
on the system when a failure first occurs and before a
detach of a failing object is performed, but can lead to
memory starvation.
volraid_rsrtransmax
503Performance monitoring and tuning
Tuning VxVM