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livedump(5)

HP-UX 11i Version 3: February 2007
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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. If Live 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

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