HP-UX System Administrator's Guide: Overview

When you define dump devices, whether in a kernel build or at run time, you can list
which classes of memory must always get dumped and which classes of memory should
not be dumped. If you leave both of these lists empty HP-UX will decide for you which
parts of memory should be dumped based on what type of error occurred. In nearly
all cases it is best to let HP-UX determine which pages to dump.
IMPORTANT: You can interrupt the dump at any time by pressing the ESC (escape)
key. It can take as long as 15 seconds to abort.
If you interrupt a dump, it will be as though a dump never occurred; that is, you will
not get a partial dump.
Even if you have defined that you do not want a full dump to be performed, an operator
at the system console at the time of a crash can override those definitions and request
a full dump.
Likewise, if at the time of a crash you know what caused it (and therefore do not need
the system dump) but have previously defined a full or selective dump an operator at
the system console at the time of a crash can override those definitions and request
that no dump be performed.
Concurrent Dumps
On servers with very large amounts of memory, the process of writing memory contents
to disk can take a very long time. If you have multiple devices configured to receive
the memory dump you can configure HP-UX to split the task of dumping memory and
write to the multiple devices in parallel. This process is called dump concurrency and is
configured using either the kernel tunable dump_concurrent_on (see
dump_concurrent_on(5)), or the crash-processing configuration command crashconf
(see crashconf(1M)).
NOTE: Concurrent dump performance improvements are not likely to occur on
systems with only one instance of any of the crash dump resources (for example, only
one dump device or only one core). And, concurrent dump performance improvements
are currently supported only on HP Integrity servers.
Compressed Dumps
Following a system crash, the HP-UX operating system can use this feature to compress
data from memory before it writes the data to the dump device. Compression decreases the
volume of crash data, making the dump times faster.
Start-up and Shutdown 97