SNAX/XF and SNAX/APN Configuration and Management Manual

SCF Commands for SNAX/XF and SNAX/APN
SNAX/XF and SNAX/APN Configuration and Management Manual—425836-006
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TRACE Command
first occurs, the source of the problem is often unknown, and it is likely that the problem
will not be captured in a trace if only specific objects are selected. Once you have
isolated the problem to a particular object or set of objects, you can selectively trace
those objects.
NOCOLL
Whenever a line trace or a service-manager trace is started, the trace facility creates
an extended segment within the process’s context and writes trace data to the
segment.
When NOCOLL is not specified, a separate process (the trace collector process) reads
the data from the extended segment and writes the data to a disk file.
When NOCOLL is specified, there is no collector process, so the number of records
that can be written to the trace file is determined by the size of the extended segment
(see the recommendations for the PAGES option). Trace records wrap within the
segment, so that older records are replaced with newer ones. Thus only a limited
number of records can be traced when NOCOLL is specified.
If a collector is running, the collector moves the data from the extended segment to the
disk file while trace data is being collected. Therefore, a large number of records can
be traced, limited only by the size of the disk file.
At times the tracing process may write records to the extended segment faster than the
collector can write them to disk. In this case, wrapping occurs within the extended
segment. If wrapping would cause the tracing process to write over trace records not
yet copied to disk, then the tracing stops until those records are written to disk. During
that time, a number of records may not be traced. A trace record is placed in the disk
file to indicate the number of records that were missed.
The recommendation, therefore, is not to specify NOCOLL unless the tracing rate is
such that the collector cannot keep up with the tracing, and unless the problem can be
captured within the relatively small number of records that can be contained within the
extended segment (see the recommendations for the PAGES and RECSIZE options).
PAGES
This option specifies the number of pages allocated in the tracing process’s extended
segment, which contains the trace records. If the value is small and NOCOLL is not
specified, the trace collector may not be able to keep up with the tracing rate. If
NOCOLL is specified, this option also determines the number of records to be placed
in the trace file on disk; therefore, a small value limits the number of records that can
be traced. Therefore, the maximum value is recommended unless CPU memory
limitations are an issue.
RECSIZE
This option specifies the maximum size of any record placed in the trace file. If its
value is too small, trace records are truncated and significant data can be lost. For