Technical data

SDA Description
When a fatal error causes the system to fail, the operating system copies the
contents of memory to a system dump file; the system also records the hardware
context of each processor in the system.
The System Dump Analyzer (SDA) provides a means of interpreting the contents
of the system dump file, thus enabling you to examine the status of each processor
at the time of the failure and to investigate the probable causes of the crash.
To examine the system dump file, you invoke SDA by using the DCL command
ANALYZE/CRASH_DUMP. You can also invoke SDA to analyze a running system,
using the DCL command ANALYZE/SYSTEM. Most SDA commands generate
useful output in this mode of operation.
Caution
Although the analysis of a running system might be instructive, be aware
that system context, process context, and a processor’s hardware context
remain fluid during any given display. In a multiprocessing environment,
a process running SDA might be rescheduled to a different processor
frequently during analysis. Therefore, Compaq recommends that you not
examine the hardware context of processors in a running system.
Following are brief explanations of SDA qualifiers. Details about these qualifiers
are in the SDA Qualifiers section.
Qualifier Description
/CRASH_DUMP Invokes SDA to analyze a specified dump file
/RELEASE Invokes SDA to release those blocks that are occupied by a crash
dump in a specified system paging file
/SYMBOL Specifies a system symbol table for SDA to use in place of the
system symbol table it uses by default (SYS$SYSTEM:SYS.STB)
/SYSTEM Invokes SDA to analyze a running system
The following tables show the SDA commands that you can use to perform
operations within the SDA utility. These commands are in groups of related
information. Details about SDA commands are in the SDA Commands section.
Table SDA–1 describes information that you can select and display about
processes.
Table SDA–1 Selecting and Displaying Information About Processes
Operation SDA Command
Display the condition of the operating system and the
hardware context of each processor in the system at the
time of a crash
SHOW CRASH
Display a summary of all processes on the system SHOW SUMMARY
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SDA–1