dump_compress_on(5)dump_compress_on(5)NAMEdump_compress_on - selects whether the system dumps memory pages com‐
pressed or uncompressed when a kernel panic occurs
(Allow the kernel to decide whether to dump compressed or not based on
the system state at the time of the crash.)
Integer values and
The setting for is used as follows:
Dump with compression for speed if possible.
(Allow the kernel to choose dump mode.)
The value the kernel usually chooses is 1.
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 capa‐
bility 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
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 uncom‐
pressed 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
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
When Should the Tunable Be Turned Off?
The tunable should be turned off if there is a problem with compressed
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?
All HP-UX kernel tunable parameters are release specific. This parame‐
ter may be removed or have its meaning changed in future releases of
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 val‐
ues. For information about the effects of installation on tunable val‐
ues, consult the documentation for the kernel software being installed.
For information about optional kernel software that was factory
installed on your system, see at
was developed by Hewlett-Packard Company.
SEE ALSOcrashconf(1M), alwaysdump(5), dontdump(5).
Tunable Kernel Parameters dump_compress_on(5)