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

Table 15-1
Kernel tunable parameters for VxVM (continued)
DescriptionParameter
The maximum number of dirty regions that can exist
on the system for non-sequential DRL on volumes. A
larger value may result in improved system
performance at the expense of recovery time. This
tunable can be used to regulate the worse-case recovery
time for the system following a failure.
The default value is 2048.
voldrl_max_drtregs
The minimum number of sectors for a dirty region
logging (DRL) volume region. With DRL, VxVM logically
divides a volume into a set of consecutive regions.
Larger region sizes tend to cause the cache hit-ratio
for regions to improve. This improves the write
performance, but it also prolongs the recovery time.
The default value is 512 sectors.
If DRL sequential logging is configured, the value of
voldrl_min_regionsz must be set to at least half
the value of vol_maxio.
voldrl_min_regionsz
The granularity of memory chunks used by VxVM when
allocating or releasing system memory. A larger
granularity reduces CPU overhead due to memory
allocation by allowing VxVM to retain hold of a larger
amount of memory.
The default value is 65536 bytes (64KB).
voliomem_chunk_size
Performance monitoring and tuning
Tuning VxVM
500