Managing Systems and Workgroups: A Guide for HP-UX System Administrators
Administering a System: Booting and Shutdown
Abnormal System Shutdowns
Chapter 5 533
• 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
The dump process exists so that you have a way of capturing what your
system was doing at the time of a crash. This is not for recovery
purposes; processes cannot resume where they left off, following a
system crash. Rather this is for analysis purposes, to help you determine
why the system crashed in order to prevent it from happening again.
If you want to be able to capture the memory image of your system when
a crash occurs (for later analysis), you need to define in advance the
location(s) where HP-UX puts that image at the time of the crash. This
location can be on local disk devices, or logical volumes.
Wherever you decide that HP-UX should put the dump, it is important to
have enough space at that location (see “How Much Dump Space Do I
Need?” on page 543) If you do not have enough space, not every page will
be saved and you might not capture the part of memory that contains the
instruction or data that caused the crash. If necessary, you can define
more than one dump device so that if the first one fills up, the next one is
used to continue the dumping process until the dump is complete or no
more defined space is available. To guarantee that you have enough
dump space, define a dump area that is at least as big as your computer’s
physical memory, plus one megabyte. If you are doing a selective dump
(which is the default dump mode in most cases), much less dump space
will actually be needed. Full dumps require dump space equal to the
size of your computer’s memory plus a little extra for header information.
In HP-UX Release 11i compressed dumps are enabled by default.
However, dump compression will only occur if conditions in the crash
environment are favorable. Do not plan your dump storage space based
on potential compression but allow enough space for an uncompressed
full or selective dump. See “Compressed Dump” on page 536.
Normal Operation
SYSTEM
CRASH!