Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Administering a System: Managing Disks and Files
Managing Swap and Dump
Chapter 6672
longer need to contain the entire contents of physical memory. With
expanded physical memory limits, you may wish to dump only those
classes of physical memory which you will use in a crash dump analysis.
Further, you now have an additional way to configure dump devices: In
addition to reconfiguring the kernel, at 11.0, you can also do dump
configuration at runtime using the crashconf (1M) command without the
need to reboot the system.
You can use either of two ways to configure which classes of memory
should be included in a dump. crashconf options can be used, or this
information can be configured using the tunable parameters alwaysdump
or dontdump when you reconfigure the kernel.
You can use SAM to add, remove, or modify dump devices, and to
configure how much of the dump you wish to retain. For more
information, see SAM’s online help.
How Much Disk Space Should Be Used for Dump?
The amount of disk space made available for core dumps should
accommodate your system’s physical (core) memory. As a result of the
larger physical memory limits of the 64-bit hardware platforms
introduced at 11.0, you may need to significantly increase the amount of
disk space for dump on these systems. (If you need to determine the
amount of physical memory on your system, see “Estimating Your Swap
Space Needs” on page 664.)
Because the physical memory on your system may exceed the space
available in the primary swap area, you may wish to configure additional
disk space for the full core memory image. Otherwise, only a partial core
image will be saved which may not be sufficient for analyzing problems.
Configuring Dump Areas Using HP-UX Commands
If you do not use SAM to configure your dump areas, you should follow
the guidelines below:
Although dump areas can be configured within disk sections, it is
preferable to use logical volumes.
A dump logical volume can exist only within the root volume group, that
is, the volume group that contains the root logical volume.