livedump.5 (2010 09)

l
livedump(5) livedump(5)
NAME
livedump - a feature that saves operating system state to the file system for debugging purposes.
DESCRIPTION
Live Dump is a feature by which a running operating system’s state can be saved to the filesystem
without stopping/rebooting the system. The saved dump can be used for debugging purposes.
Live Dump saves the information in a existing dump format readable by the system crash dump access
library, libcrash. See libcrash (5).
Live Dump saves the images and related files in the directory path
/ldump.n. The trailing n in the
directory name is a number that increases by one every time
Live Dump is run with the same path.
This number is stored in the file path
/lbounds. If the lbounds file does not exist in the configured
path then it is created and the default value of 2 is stored in it.
Live Dump supports both blocking and non-blocking invocation. In a blocking invocation, the control
will be returned to the invoker only after
Live Dump completes.
In case of a non-blocking invocation, the control will be returned to the callee and the user can query the
status of
Live Dump by using the
livedump command.
For blocking mode invocation,
Live Dump
messages will be printed on the user console, and for non-
blocking mode invocation,
Live Dump messages are stored in the syslog file
/var/adm/syslog/syslog.log
.
Live Dump supports selective dump using page classification similar to crash dump. Live Dump uses
filesystem space to save the operating system state. The amount of filesystem space to be left free can be
configured by the user. The operating system state saved by
Live Dump is in the form of image files.
The maximum size of each image is also configurable by the user. The location on the filesystem where
Live Dump saves the system state can be set by the user.
Live Dump configuration can be queried/changed using the
livedump utility. See livedump (1M) for
more details.
The dump saved by
Live Dump is not a snapshot of system memory. Instead it is the state over a period
of time. As the system state keeps changing continuously (when Live Dump is in progress), the dump
taken would be a transient one. Due to this transientness some data structures may be broken in the
dump.
Definitions
minfree Amount of space to be left free upon completion of
Live Dump.IfLive Dump
detects
that the free disk space has fallen below minfree value, it stops saving the dump. The
saved dump, in this case, may not be debuggable.
chunksize Size of a single physical memory image file. See livedump (1M) for details.
pageclass System memory classes. See crashconf (2) for details on defined system memory classes.
Live Dump does not support saving of the buffer cache and unused pages.
sid The session id associated with every
Live Dump session. Live Dump generates this id
for each invocation in order to identify a Live Dump session uniquely. The user can use
this id to specify the Live Dump session to be aborted.
path Directory to save the
Live Dump. If this option is not specified, then
/var/adm/crash is used as the default directory to save the dump.
AUTHOR
The
Live Dump feature described here was developed by Hewlett-Packard.
FILES
/var/adm/syslog/syslog.log messages saved by Live Dump
SEE ALSO
livedump(1M), crashconf(2), libcrash(5).
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1