VERITAS Volume Manager 4.1 Administrator's Guide

Performance Monitoring and Tuning
Tuning VxVM
Chapter 12 413
voliomem_maxpool_sz
The maximum memory requested from the system by VxVM for internal
purposes. This tunable has a direct impact on the performance of VxVM
as it prevents one I/O operation from using all the memory in the system.
VxVM allocates two pools that can grow up to voliomem_maxpool_sz,
one for RAID-5 and one for mirrored volumes.
A write request to a RAID-5 volume that is greater than
voliomem_maxpool_sz/10 is broken up and performed in chunks of size
voliomem_maxpool_sz/10.
A write request to a mirrored volume that is greater than
voliomem_maxpool_sz/2 is broken up and performed in chunks of size
voliomem_maxpool_sz/2.
The default value for this tunable is 4M.
NOTE The value of voliomem_maxpool_sz must be at least 10 times greater
than the value of vol_maxio.
voliot_errbuf_default
The default size of the buffer maintained for error tracing events. This
buffer is allocated at driver load time and is not adjustable for size while
VxVM is running.
The default size for this buffer is 16384 bytes (16KB).
Increasing this buffer can provide storage for more error events at the
expense of system memory. Decreasing the size of the buffer can result in
an error not being detected via the tracing device. Applications that
depend on error tracing to perform some responsive action are dependent
on this buffer.
voliot_iobuf_dflt
The default size for the creation of a tracing buffer in the absence of any
other specification of desired kernel buffer size as part of the trace
ioctl.
The default size of this tunable is 8192 bytes (8KB).