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 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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