Installation guide

Saving Memory Dumps
5-44 Fault Tolerant System Administration (R1004H) HP-UX version 11.00.03
Dump Space Needed for Full System Dumps
The amount of dump space you need to define is based on the size of the system’s
physical memory.
NOTE
During the startup sequence, save_mcore is invoked automatically. If
sufficient space is not available in /var/adm/crash to hold a file equal
to the size of physical memory, dumping will fail, leaving the system
simplexed. At this time, you can run save_mcore manually and then
use the ftsmaint sync command to duplex the system.
Although save_mcore copies a dump directly from memory to
/var/adm/crash, savecrash needs space on dump volume(s) in addition to
space on /var/adm/crash. Dump volumes need to be as large as physical
memory. (Note that dump volumes can also be used as swap volumes.) Ensure
that /var/adm/crash has sufficient space to hold two full dumps. If your
system does not have sufficient space, mount a file system onto /var/adm/crash
to provide adequate space. If possible, 4 GB or larger disks should be used for any
large memory VxFS file system dumps.
Dump Space Needed for Selective Dumps
For selective dumps, the size of your dump space needs vary, depending on which
classes of memory you are saving. To obtain a more accurate estimate your needs,
enter the following command when the system is up and running, with a fairly
typical work load:
/sbin/crashconf -v
Output, similar to the following, is displayed:
CLASS PAGES INCLUDED IN DUMP DESCRIPTION
UNUSED 2036 no, by default unused pages
USERPG 6984 no, by default user process pages
BCACHE 15884 no, by default buffer cache pages
KCODE 1656 no, by default kernel code pages
USTACK 153 yes, by default user process stacks
FSDATA 133 yes, by default file system metadata
KDDATA 2860 yes, by default kernel dynamic data
KSDATA 3062 yes, by default kernel static data
Total pages on system: 32768
Total pages included in dump: 6208
DEVICE OFFSET(kB) SIZE (kB) LOGICAL VOL. NAME
31:0x00d000 52064 262144 64:0x000002 /dev/vg00/lvol2
262144