HP-UX System Administrator's Guide: Overview

Crash Information Integrity
Use this section if your most important criterion is to make sure you capture the part of
memory that contains the instruction or piece of data that caused crash. The factors
you have to consider here are:
• Full Dump versus Selective Dump
• Dump Definitions Built into the Kernel
• Using a Device for Both Paging and Dumping (Crash Integrity)
Full Dump versus Selective Dump
You have chosen this section because it is critical to you to capture the specific
instruction or piece of data that caused your system crash. The only way to guarantee
that you have it is to capture everything. This means selecting to do a full dump of
memory.
Be aware, however, that this can be costly from both a time and a disk space perspective.
From the time perspective, it can take quite a while to dump the entire contents of
memory from an HP-UX instance using very large amounts of memory. It can take an
additional large amount of time to copy that memory image to the HP-UX file system
area during the reboot process.
From the disk space perspective, if you have large amounts of memory (some HP-UX
servers can have terabytes of memory), you will need an amount of dump area at least
equal to the amount of memory in your system; and, depending on a number of factors,
you will need additional disk space in your HP-UX file system area equaling the amount
of physical memory in your system, in the worst case.
Dump Definitions Built into the Kernel
You can configure HP-UX dump devices using one or more of the following methods:
• Preferred Method: At run time using the /sbin/crashconf command
• At boot time (entries defined in the /etc/fstab file)
• During kernel configuration (put the definitions in the /stand/system file). This
method is obsolescent and should no longer be used!
Definitions at each of these places add to or replace any previous definitions from the
other sources. However, consider the following situation:
100 Major Components of HP-UX