HP-UX HB v13.00 Ch-08 - Crash Dumps

HP-UX Handbook – Rev 13.00 Page 10 (of 38)
Chapter 08 Crash Dumps
October 29, 2013
How to configure dump devices
In order to understand the following text you should be familiar with the basic concept of the
Logical Volume Manager LVM. I make use of these abbreviations:
VG = Volume Group
LV = Logical Volume
PV = Physical Volume
Choosing dump devices
Dump devices are volumes on the disk that are used to hold the entire memory image when the
system crashes. The cumulative size of all specified dump devices has to be some MB larger
than the amount of memory in order to hold the entire core. To determine the current size of
physical memory:
# dmesg | grep Physical
Physical: 524288 KB, lockable: 386672 KB, available: 454144 KB
As of UX 11.00 you can use crashconf(1M):
# crashconf | grep Total
Total pages on system: 131072
Total pages included in dump: 30832
(A page is always 4KB)
NOTE: Increasing the amount of dump space is an important thing to do when adding more
physical memory to the system.
Formerly the maximum size of a dump device was 2GB or more precise: the dump LV had to be
placed within the first 2GB of the PV whereas newer systems support dump devices up to 4GB
or since UX 11.00 even greater than 4GB.
It's important to mention that it's the Interface Card, not the disk, that defines whether the disk
can be used for more than 4GB of dump. Cards in the systems like L-, N-, V-Class and newer all
support this. Details can be found in KMINE document S3100004913.
A swap device can also be used as dump device in order to save disk space but there are two
disadvantages:
1) Is the primary swap device (usually /dev/vg00/lvol2) also configured as dump device, it
takes more time for the system to bootup after a systemcrash.
Reason: When a dump is found on the dump device during startup it will be written to the