dump_compress_on(5) File Formats Manual dump_compress_on(5)
NAME
dump_compress_on - selects whether the system dumps memory pages compressed or uncompressed when a kernel panic occurs
VALUES
Failsafe
Default
(Allow the kernel to decide whether to dump compressed or not based on the system state at the time of the crash.)
Allowed value
Integer values and
The setting for is used as follows:
Dump uncompressed.
Dump with compression for speed if possible.
Recommended values
(Allow the kernel to choose dump mode.)
The value the kernel usually chooses is 1.
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. Compressed dump capability results in smaller and faster dumps that will also take lesser
time to save over into the filesystem.
The (see crashconf(1M)) command and its associated configuration file control the dump compression mode in the memory dumps associated with
a system crash. On rare occasions, the system may crash before is run during the boot process. On those occasions, the configuration set
using the tunable will be used.
The default value for this parameter is The system determines whether or not to dump compressed based on the type of crash that occurs, in
this case.
Note that certain types of system crash require an uncompressed crash dump. Also, the system operator may request an uncompressed crash
dump at the time the dump is taken. In either of these cases, an uncompressed dump will be performed regardless of the mode selected in
Who Is Expected to Change This Tunable?
Only HP Field engineers should change the value of this tunable.
Restrictions on Changing
Changes to this tunable take effect immediately.
When Should the Tunable Be Turned On?
This tunable should be turned on to dump compressed when there is a system crash.
What Are the Side Effects of Turning the Tunable Off?
In this case, an uncompressed dump is taken always. On large memory machines, an uncompressed dump take typically three times longer than
a compressed dump.
When Should the Tunable Be Turned Off?
The tunable should be turned off if there is a problem with compressed dumps.
What Are the Side Effects of Turning the Tunable On?
The system decides the dump mode based on the type of crash.
What Other Tunables Should Be Changed at the Same Time?
None.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its meaning changed in future releases of
HP-UX.
Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parameter values. After installation,
some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tun-
able values, consult the documentation for the kernel software being installed. For information about optional kernel software that was
factory installed on your system, see at
AUTHOR
was developed by Hewlett-Packard Company.
SEE ALSO
crashconf(1M), alwaysdump(5), dontdump(5).
Tunable Kernel Parameters dump_compress_on(5)