TFDS Manual

Tandem Failure Data System (TFDS) Manual—520628-003
F-1
F Fast Memory Dump
Fast Memory Dump (FMD) speeds processor dumping and reloading after a software
halt has halted a processor. FMD is primarily for the NonStop S76000 and S86000 with
processor memory size up to and including 16 gigabytes. The amount of time to take a
CPU dump if a processor has halted is significant. The major benefit of FMD is a
reduction in the time that a processor remains unavailable for use after halting.
Automating the process through TFDS simplifies its use. This feature is active when
the parameter FMDUMP is enabled. TFDS automatically enables FMDUMP at TFDS
startup if it determines that any of the system processors has more than 2 gigabyte of
memory. FMDUMP can be disabled by setting the TFDS configuration file variable
FMDUMP to OFF. HP cautions you not to do this because it will delay getting the
processor back online. FMDUMP mode should also be enabled if a processor with
more than 2 gigabytes of memory is added to the system or a current processor is
upgraded to more than 2 gigabytes of memory. TFDS must be stopped and restarted
to recognize this condition. If the configuration variable FMDUMP is OFF in the TFDS
configuration file, remove this statement prior to restarting TFDS.
FMD Processing Steps
FMD processing consists of five conceptual steps. A helper process is run in each of
these steps. (The following steps assume that FMD mode is set.)
1. CPU HALT incident analysis (via Garth)
2. Initial dump (partial dump via RCVDUMP)
3. Processor reload with partial memory availability (via RELOAD)
4. Post-reload dump (partial dump via PRDUMP)
5. Fixup utility to relate the two CPU dumps (via DUMPUTIL)
CPU HALT Incident Analysis
Incident analysis is initiated immediately after TFDS receives a system message
indicating that a processor has halted. TFDS must first determine if this is a hardware
or software halt.
For a hardware halt, TFDS issues an event indicating it is a hardware halt. TSM
processes this halt. TFDS takes no further action on a hardware halt.
Note. The addition of the FMD processing mode does not impact the ability of TFDS to
suppress duplicate dumps. With the DUMPOVERRIDE parameter OFF, duplicate dumps from
a non-FMD processor or an FMD-capable processor are suppressed.
Note. Neither the initial dump nor post-reload dump process is started if the incident is
determined to be a rediscovery. The addition of FMD to TFDS has not changed this feature.