HP-UX System Administrator's Guide: Overview

At other times, the cause of the crash might not be so obvious. In extreme cases, you
might want or need to analyze a snapshot of the computer’s memory at the time of the
crash, or have HP do it for you, in order to determine the cause of the crash.
Overview of the Dump / Save Cycle
When the system crashes, in order to preserve the evidence of what caused the crash,
HP-UX tries to save the image of physical memory, or certain portions of it, to predefined
locations called dump devices. When the system is subsequently rebooted, a special
utility copies the memory image from the dump devices to the HP-UX file system area.
Figure 3-8 The Crash Dump Sequence
Normal Operation
✘
System Crash!
System Reboot
Resume
Normal Operation
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
256M
hp.1234
Physical Memory
1
2
3
Reboot Processing
Crash-time
Processing
Dump Devices
HP-UX
File System Disks
When the memory image is in the HP-UX file system, you can analyze it with a debugger
or save it to removable media for shipment to someone else for analysis.
There are multiple ways that dump devices can be configured:
• In the kernel
• During system initialization when the initialization script for crashconf runs
(and reads entries from the /etc/fstab file)
• During run time, by an operator or administrator manually running the
/sbin/crashconf command
Preparing for a System Crash
94 Major Components of HP-UX