Compressed Save Vs. Noncompressed Save; Using A Device For Both Paging And Dumping; Partial Save - HP 9000 V-Class Operator's Manual

Recovering from failures
Abnormal system shutdowns
NOTE Even if you have defined (in the kernel or at run time) that you do not
want a full dump to be performed, you can override the definitions
(within a ten second window) and request a full dump after a system
crash. Likewise, if you know what caused the crash, you can override
those definitions and request no dump be performed.

Compressed save vs. noncompressed save

System dumps can be so large that they tax the HP-UX file system area.
The boot time utility, savecrash, can be configured (by editing the file /
etc/rc.config.d/savecrash) to compress or not compress the data
as it copies the memory image from the dump devices to the HP-UX file
system area during the reboot process. This effects system recovery time
in that data compression takes longer. Therefore, if you have enough disk
space and require the fastest system recovery, configure savecrash to
not compress the data. See the savecrash(1M) man pages for more
information.

Using a device for both paging and dumping

It is possible to use a specific device for both paging (swapping) and as a
dump device. If system recovery time is critical, do not configure the
primary paging device as a dump device.
When the primary paging device is not used as one of the dump devices
or after the crash image on the primary paging device has been saved, by
default, savecrash runs in the background. This reduces system boot
time by running the system with only the primary paging device.
Another advantage to keeping paging and dump devices separate is that
paging does not overwrite the information stored on a dump device, no
matter how long the system has been up or how much activity has taken
place. Disabling savecrash processing at boot time (by editing the file
/etc/rc.config.d/savecrash) reduces system recovery time. After
the system recovery, you can run savecrash manually to copy the
memory image from the dump area to the HP-UX file system area.

Partial save

If a memory dump resides partially on dedicated dump devices and
partially on devices that are also used for paging, you can save only those
pages that are endangered by paging activity.
Pages residing on the dedicated dump devices can remain there. If you
know how to analyze memory dumps, it is even possible to analyze them
directly from the dedicated dump devices using a debugger that supports
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