Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

Table 16-1
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 maximum number of dirty regions allowed for
sequential DRL. This is useful for volumes that are usually
written to sequentially, such as database logs. Limiting the
number of dirty regions allows for faster recovery if a crash
occurs.
The default value is 3.
voldrl_max_seq_dirty
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 64KB.
voliomem_chunk_size
Performance monitoring and tuning
Tuning VxVM
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