HP-UX Reference (11i v2 03/08) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)
a
alwaysdump(5) alwaysdump(5)
(Tunable Kernel Parameters)
NAME
alwaysdump - defines which classes of kernel memory pages are dumped when a kernel panic occurs
VALUES
Failsafe
0
Default
0 (Allow the kernel to choose which classes to dump.)
Allowed values
Integer values from 0 to 255.
The integer value should be the sum of the integer values for the included classes as follows:
UNUSED 1 : Unused pages
USERPG 2 : User pages
BCACHE 4 : Buffer cache
KCODE 8 : Kernel text pages
USTACK 16 : Process stack
FSDATA 32 : File-system Metadata
KDDATA 64 : Kernel dynamic data
KSDATA 128 : Kernel static data
Recommended values
0 (Allow the kernel to choose which classes to dump.)
The value the kernel usually chooses is
240 = KSDATA + KDDATA + FSDATA + USTACK.
KSDATA and KDDATA are needed for debugging any kernel problem. FSDATA is needed for debugging
file system problems. USTACK is needed for debugging problems involving user space applications.
UNUSED, USERPG, BCACHE, and KCODE are not usually needed for debugging.
DESCRIPTION
On large systems, the time required to dump system memory when a kernel panic occurs can be excessive
or even prohibitive, depending on how much physical memory is installed in the system. Fast-dump
capabilities controlled by the
dontdump and alwaysdump parameters provide a means for restricting
kernel dumps to specific types of information:
. Unused Physical Memory
. User Proces
. Buffer cache
. Kernel Code
. Process Stack
. File-System Metadata
. Kernel Dynamic Data
. Kernel Static Data
The
crashconf command, and its associated configuration file /etc/rc.config.d/crashconf
,
control which of these memory classes are to be included in the memory dumps associated with a kernel
panic. On rare occasions, the system may panic before crashconf(1M) is run during the boot process. On
those occasions, the configuration can be set using the
alwaysdump and dontdump tunables.
The bit-map value stored in
alwaysdump specifies which of these memory classes are to be included in
the memory dumps associated with a kernel panic.
The default value for this parameter is
0. The system determines whether or not to dump classes of
memory based on the type of crash that occurs, in this case.
Section 5−−38 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: August 2003