System Administration Guide

Enabling and Disabling Crash Dumps

Enabling a system to save crash dumps involves:

Creating a crash dump directory
Defining how much disk space to allow for a crash dump file
Editing the /etc/init.d/sysetup file to activate the saving of crash dump files

Disabling your system from saving crash dumps involves reversing these procedures.

How to Create a Crash Dump Directory

Become superuser.

Create the /var/crash directory.
# mkdir /var/crash

Change to the /var/crash directory.
# cd /var/crash

Create a directory with the name of the system.
# mkdir system-name
system-name

The system for which you want to save crash dump files.

Verify the directory has been created.
# ls system-name

Example--Creating a Directory to Save Crash Dump Files

The following example shows how to create a directory to save crash dump files for the system saturn.

# mkdir /var/crash
# cd /var/crash
# mkdir saturn
# ls
 saturn

How to Reserve Space for Crash Dump Files

Be sure you have completed any required tasks identified in Table 69-1.

Become superuser.

Change to the /var/crash/system-name directory.
# cd /var/crash/system-name
system-name

The system for which you want to save crash dump files.

Using the editor of your choice, create a file named minfree that contains a number specifying the minimum available free space (in kilobytes) that must remain available for crash dumps.

Exit the file, saving changes.

Example--Reserving Space for Crash Dump Files

The following example shows the contents of a minfree file that reserves 500 Kbytes of available free space to contain crash dump files for the system saturn.

$ more /var/crash/saturn/minfree
500

How to Enable Crash Dump Files

Be sure you have completed any required tasks identified in Table 69-1.

Become superuser.

Using the editor of your choice, edit the /etc/init.d/sysetup file, activating the lines that enable the crash dumps by deleting the comment marks (#) from the beginning of those lines.

Exit the file, saving the changes.

Example--Enabling Crash Dump Files

The following example shows the appropriate section of the /etc/init.d/sysetup file that has been edited to enable crash dumps.

##
## Default is to not do a savecore
##
If [ ! -d /var/crash/`uname -n` ]
then mkdir -m 0700 -p /var/crash/`uname -n`
fi
     echo 'checking for crash dump...\c '
savecore /var/crash/`uname -n`
     echo ''

How to Examine a Crash Dump

Become superuser.

Examine a crash dumps by using the crash utility.

# /usr/sbin/crash [-d crashdump-file] [-n name-list] [-w output-file]

`-d` `crashdump-file`	Specifies a file to contain the system memory image. The default crash dump file is `/dev/mem.`
`-n` `name-list`	Specifies a text file to contain symbol table information if you want to examine symbolic access to the system memory image. The default file name is `/dev/ksyms`.
`-w` `output-file`	Specifies a file to contain output from a crash session. The default is standard output.

Display crash status information.

# /usr/sbin/crash
dumpfile = /dev/mem, namelist = /dev/ksyms, outfile = stdout
> status
   .
   .
   .
> size buf proc queue
   .
   .
   .

Example--Examining a Crash Dump

The following example shows sample output from the crash utility. Information about status, and about the buffer, process, and queue size is displayed.

# /usr/sbin/crash
dumpfile = /dev/mem, namelist = /dev/ksyms, outfile = stdout
> status
system name:    SunOS
release:        5.6
node name:      saturn
version:        Generic
machine name:   sun4m
time of crash:  Fri Jan 10 14:14:39 1997
age of system:  60 day, 5 hr., 24 min.
panicstr:
panic registers:
        eip: 0     esp: 0
> size buf proc queue
120
1552
88

How to Disable Crash Dump Files

Become superuser.

Edit the /etc/init.d/sysetup file, inserting a comment mark (#) at the beginning of each of the lines shown below.

#if [ ! -d /var/crash/`uname -n` ]
#then mkdir -p /var/crash/`uname -n`
#fi
#                echo `checking for crash dump...\c `
#savecore /var/crash/`uname -n`
#                echo ''

Save the changes.

Remove the file set up for crash dumps from the /var/crash directory.
# rm -rf /var/crash/system-name
system-name

Name of the system which will no longer save crash dump files.