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

Table 15-1
Kernel tunable parameters for VxVM (continued)
DescriptionParameter
The upper limit to the size of memory that can be used
for storing tracing buffers in the kernel. Tracing
buffers are used by the VxVM kernel to store the
tracing event records. As trace buffers are requested
to be stored in the kernel, the memory for them is
drawn from this pool.
Increasing this size can allow additional tracing to be
performed at the expense of system memory usage.
Setting this value to a size greater than can readily be
accommodated on the system is inadvisable.
The default value is 131072 bytes (128KB).
voliot_iobuf_limit
The maximum buffer size that can be used for a single
trace buffer. Requests of a buffer larger than this size
are silently truncated to this size. A request for a
maximal buffer size from the tracing interface results
(subject to limits of usage) in a buffer of this size.
The default value is 65536 bytes (64KB).
Increasing this buffer can provide for larger traces to
be taken without loss for very heavily used volumes.
Care should be taken not to increase this value above
the value for the voliot_iobuf_limit tunable value.
voliot_iobuf_max
The maximum number of tracing channels that can be
open simultaneously. Tracing channels are clone entry
points into the tracing device driver. Each vxtrace
process running on a system consumes a single trace
channel.
The default number of channels is 32.
The allocation of each channel takes up approximately
20 bytes even when the channel is not in use.
voliot_max_open
Performance monitoring and tuning
Tuning VxVM
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