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Analyzing Crash Dumps
Remote Dump Analysis
Remote Dump Analysis
KWDB supports remote dump analysis. Using this feature KWDB can be used to analyze crash dumps
located on a remote system. To support this feature a program, kwdbcr, has to be run on the remote system
where crash dump is located. The kwdbcr program handles requests from KWDB client to open and read data
from the crash dump. From kwdb 3.1.3 onwards, it is possible to daemonize kwdbcr so that it is unnecessary
to rerun kwdbcr each time to analyze a crash dump from a remote host running kwdb client. Here are the
steps involved in analyzing a remote crash dump.
1. Copy the kernel file, usually vmunix and DLKM modules if any, from the remote system to the local
system where KWDB client is going to be run. KWDB reads all symbols information from these files. Only
data from the crash dump is read from the remote system.
NOTE
From kwdb 3.1.3 onwards, kwdb, when started on a remote crash dump, automatically
copies vmunix and modules from the crash dump and caches them in the host machine
under $HOME/.kwdb/remotefiles. The contents of this cache are intended for kwdb’s own
internal usage, and can be removed by kwdb from time to time. The default size of this
cache is 120 MB, but can be configurable through kwdb by running the set kwdb
remote_file_cache_size <size_in_MB> command. It may also be noted that the size of
this cache can marginally increase during copying of a remote vmunix/module if total usage
of the cache for the current kwdb session is more than 120 MB (or the size specified by
running the set kwdb remote_file_cache_size command).
2. Invoke kwdbcr on the remote system with crash dump directory name as the argument. Specify optional
arguments, a port number to use for connection, and a filename, if desired, to log messages. kwdbcr -help
will display the usage of kwdbcr as shown:
# kwdbcr -help
kwdbcr : Program to be run on remote system for remote crash dump analysis using kwdb.
Usage : kwdbcr [port] [crash_path] [-l logfile]
port - port number for kwdb to connect.
By default a free port above 47001 is used.
crash_path - crash dump directory path.
By default current directory is used.
logfile - filename to log messages.
By default ./kwbcr.log is used.
# kwdbcr -d [-l logfile]
-d option runs kwdbcr as a daemon
#kwdbcr -v
-v option displays the kwdbcr version information
After successfully starting, kwdbcr displays a message (including a port number for use by KWDB) for
connecting to this server program as shown in the following example:
# kwdbcr /var/adm/crash.0
Analysing crash dump at /var/adm/crash.0 through port 47003
Start kwdb on the host using :
kwdb -q4 vmunix remote system:47003
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