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

Administering a System: Booting and Shutdown
Abnormal System Shutdowns
Chapter 5 535
dump subsystem is available to you that will give you a lot more control
over the dump process. An operator at the system console can even
override the runtime configuration as the system is crashing.
In addition to any previous options you had, you now have control over
the following crash dump features:
• How much memory gets dumped.
• Run-time crash dump configuration. It is no longer necessary to
build your dump configuration into the kernel file or to reboot the
system to change the crash dump configuration.
• Whether or not a dump is compressed.
These new capabilities give you a lot more flexibility, but you need to
make some important decisions regarding how you will configure your
system dumps. There are three main criteria to consider. Select which of
these is most important to you and read the corresponding section. The
criteria are:
• “System Recovery Time” on page 535
• “Crash Information Integrity” on page 539
• “Disk Space Needs” on page 541
System Recovery Time
Use this section if the most important criteria to you is to get your
system back up and running as soon as possible. The factors you have to
consider here are:
• “Dump Level: Full Dump, Selective Dump, or No Dump” on page 535
• “Compressed Dump” on page 536
• “Compressed Save versus Noncompressed Save” on page 539
• “Using a Device for Both Paging and Dumping” on page 539
Dump Level: Full Dump, Selective Dump, or No Dump In addition to
being able to choose “dump everything” or “dump nothing,” as of HP-UX Release
11.0 you have the ability to determine which classes of memory pages get
dumped.
You are reading this section because system recovery time is critical to you.
Obviously, the fewer pages your system needs to dump to disk (and on reboot,
copy to the HP-UX file system area), the faster your system can be back up and
running. Therefore, if possible, avoid using the full dump option.