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148 Chapter 7
Recovering from failures
Abnormal system shutdowns
The on-disk and file system formats of a crash dump have changed with
HP-UX 11.0.
libcrash(3) is a new library provided to allow programmatic access to a
crash dump. supports all past and current crash dump formats. By using
libcrash(3) under certain configurations, crash dumps no longer need
to be copied into the file system before they can be debugged. See the
libcrash(3) man page for more information.
Overview of the dump and save cycle
When the system crashes, HP-UX saves the image of physical memory or
certain portions of it to predefined locations called dump devices. When
the operator next reboots the system, a special utility copies the memory
image from the dump devices to the HP-UX file system area. Once
copied, the memory image can be analyzed with a debugger or saved to
tape for later analysis.
Prior to HP-UX 11.0, dump devices had to be defined in the kernel
configuration, and they still can be using Release 11.0. Beginning with
Release 11.0, however, a new more-flexible method for defining dump
devices is available using crashconf.
Beginning with HP-UX Release 11.0, there are three places where dump
devices are configured:
1. In the kernel (same as releases prior to Release 11.0)
2. During system initialization when the initialization script for
crashconf runs (and reads entries from the /etc/fstab file)
3. During runtime, by the operator or administrator manually running
the /sbin/crashconf command.
Crash dump destination and contents
Defining the contents and destination of the crash dump are two
important factors to consider when preparing for the dump. The
destination and contents are configurable without rebooting, using the
crashconf interface. See the crashconf(1M) man page for more
information.
In order to capture the memory image of the system when a crash occurs,
the image storage location(s) must be defined in advance.