SNAX/HLS Diagnosis and Support Manual

2 Using SNAX/HLS Trace Analysis
Program
104706 Tandem Computers Incorporated 2–1
Basic Components The SNAX/HLS Trace Analysis Program (HLSTAP) is a tool for SNAX/HLS system
programmers and operators to use in problem determination. HLSTAP analyzes
previously generated SNAX/HLS trace files and displays information (selected by the
user) in a high-level, easy-to-understand format.
Production of the trace files is under the control of the HLSCOM TRACE command
(described in the SNAX/HLS Configuration and Control Manual). After a trace file is
generated and closed, analysis using HLSTAP can begin.
A trace file contains two sections: the entity trace table (ETT) and the trace records:
1. The ETT contains session-level information about SNAX/HLS logical units (LUs)
in the trace. HLSTAP uses information in this ETT to format trace records. For
example, the LU name is extracted from the ETT.
For an LU to be traced by SNAX/HLS, the ETT must contain information about
the LU needed to do the trace, including a session ID. Session IDs are assigned
when an application program successfully executes an OPEN-SESSION verb or an
HLS-ALLOCATE verb. Only allocated sessions can be traced.
It is possible for more than one session to have been established as the same LU
(although not at the same time) and for all of them to have been traced to the trace
file. When this happens, an ETT is created for each session, containing
session-specific information. The LU name in each ETT is the same, but the
session may be distinguished by the session ID. Any subsequent HLSTAP
commands that operate on this LU apply to all sessions established on the LU.
2. The second section of the trace file contains a limited number of pages for
accumulating trace information. If this capacity is exceeded, the file wraps
around, overwriting the old information. Thus, for a trace that exceeds the
capacity of the file, only the last pages are available for display using HLSTAP.
The maximum length of the data in the trace data record, excluding header, is
32746 bytes.
The command syntax diagrams in this section contain several syntactic variables
(shown in italic font). The definitions of most of these are identical to those used in
the operating system. For example, the definition of file-name that applies in the
operating system applies here also.
In this manual, the term LU-specifier refers to one or more SNAX/HLS LUs.
SNAX/HLS LUs have names of the form:
$line-name.#lu-name