HP-UX System Administrator's Guide: Overview

in order to gain the space you need for the savecrash operation; or you can run the
savecrash command manually, specifying an alternate destination for the saved data.
CAUTION: If you are using your devices for both paging and dumping, do not disable
the savecrash boot processing or you will lose the dumped memory image to subsequent
system paging activity.
What to Do After the System Has Rebooted
After your system is rebooted, one of the first things you need to do is to be sure that
the physical memory image that was dumped to the dump devices is copied to the
HP-UX file system area so that you can either package it up and send it to an expert
for analysis, or analyze it yourself using a debugger.
NOTE: It is possible to analyze a crash dump directly from dump devices using a
debugger that supports this feature. But if you need to save it to removable media, or
send it to someone, you first need to copy the memory image to the HP-UX file system
area.
Unless you specifically disable savecrash processing during reboot, the savecrash
utility will copy the memory image for you during the reboot process. The default
HP-UX directory that it will put the memory image in is /var/adm/crash. You can
specify a different location by editing the file /etc/rc.config.d/savecrash and
setting the environment variable called SAVECRASH_DIR to the name of the directory
where you would like the dumps to be located. Just be sure the destination has enough
disk space to hold the copied memory image.
LiveDump (Memory Dumps of Running Systems)
Beginning with HP-UX 11i version 3, it is possible to perform dump processing on HP
Integrity servers without crashing the system and without causing instability in the system.
Live dumps (memory dumps of systems that have not crashed and are still running)
can be useful:
• For analyzing what caused some recoverable operating system faults
• In the event of failures with dynamically loadable kernel modules that do not
destabilize the kernel (for example, troubleshooting certain problems with I/O
drivers)
• For debugging problems with system performance degradation
• For analyzing a snapshot of a running kernel off line.
Live dumps can be user initiated or kernel initiated. Users with appropriate privileges
can initiate a live dump using the livedump command (see livedump(1M) for details
on how to do this).
106 Major Components of HP-UX