How to Modify a Crash Dump Configuration

1. Become superuser.

2. Identify the current crash dump configuration.

   # dumpadm Dump content: kernel pages Dump device: /dev/dsk/c0t3d0s1 (swap) Savecore directory: /var/crash/pluto Savecore enabled: yes

   This the default dump configuration for a system running the Solaris 9 release.

3. Modify the crash dump configuration.

   # dumpadm -c content -d dump-device -m nnnk | nnnm | nnn% -n -s savecore-dir

   -c content	Specifies the type of data to dump. Use kernel to dump of all kernel memory or all to dump all of memory. The default dump content is kernel memory.
   -d dump-device	Specifies the device that stores dump data temporarily as the system crashes. The primary swap device is the default dump device.
   -m nnnk | nnnm | nnn%	Specifies the minimum free disk space for saving crash dump files by creating a minfree file in the current savecore directory. This parameter can be specified in Kbytes (nnnk), Mbytes (nnnm) or file system size percentage (nnn%). The savecore command consults this file prior to writing the crash dump files. If writing the crash dump files, based on their size, would decrease the amount of free space below the minfree threshold, the dump files are not written and an error message is logged. For information on recovering from this scenario, see "How to Recover From a Full Crash Dump Directory (Optional)".
   -n	Specifies that savecore should not be run when the system reboots. This dump configuration is not recommended. If system crash information is written to the swap device, and savecore is not enabled, the crash dump information is overwritten when the system begins to swap.
   -s	Specifies an alternate directory for storing crash dump files. The default directory is /var/crash/hostname where hostname is the output of the uname -n command.

Example--Modifying a Crash Dump Configuration

In this example, all of memory is dumped to the dedicated dump device, /dev/dsk/c0t1d0s1, and the minimum free space that must be available after the crash dump files are saved is 10% of the file system space.

# dumpadm
      Dump content: kernel pages
       Dump device: /dev/dsk/c0t3d0s1 (swap)
Savecore directory: /var/crash/pluto
  Savecore enabled: yes
 # dumpadm -c all -d /dev/dsk/c0t1d0s1 -m 10%
      Dump content: all pages
       Dump device: /dev/dsk/c0t1d0s1 (dedicated)
Savecore directory: /var/crash/pluto (minfree = 77071KB)
  Savecore enabled: yes

How to Examine a Crash Dump

1. Become superuser.

2. Examine a crash dump by using the mdb utility.

   # /usr/bin/mdb [-k] crashdump-file

   -k	Specifies kernel debugging mode by assuming the file is an operating system crash dump file.
   crashdump-file	Specifies the operating system crash dump file.

3. Display crash status information.

   # /usr/bin/mdb file-name > ::status . . . > ::system . . .

Example--Examining a Crash Dump

The following example shows sample output from the mdb utility, which includes system information and identifies the tunables that are set in this system's /etc/system file.

# /usr/bin/mdb -k unix.0 
Loading modules: [ unix krtld genunix ip nfs ipc ptm ]
> ::status
debugging crash dump /dev/mem (64-bit) from ozlo
operating system: 5.9 Generic (sun4u)
> ::system
set ufs_ninode=0x9c40 [0t40000]
set ncsize=0x4e20 [0t20000]
set pt_cnt=0x400 [0t1024]

How to Recover From a Full Crash Dump Directory (Optional)

In this scenario, the system crashes but there is no room in the savecore directory, and you want to save some critical system crash dump information.

1. Log in as superuser after the system reboots.

2. Clear out the savecore directory, usually /var/crash/hostname, by removing existing crash dump files that have already been sent to your service provider. Or, run the savecore command and specify an alternate directory that has sufficient disk space. (See the next step.)

3. Manually run the savecore command and if necessary, specify an alternate savecore directory.

   # savecore [ directory ]

How to Disable or Enable Saving Crash Dumps

1. Become superuser.

2. Disable or enable the saving of crash dumps on your system.

   # dumpadm -n | -y

Example--Disabling the Saving of Crash Dumps

This example illustrates how to disable the saving of crash dumps on your system.

# dumpadm -n
      Dump content: all pages
       Dump device: /dev/dsk/c0t1d0s1 (dedicated)
Savecore directory: /var/crash/pluto (minfree = 77071KB)
  Savecore enabled: no

Example--Enabling the Saving of Crash Dumps

This example illustrates how to enable the saving of crash dump on your system.

# dumpadm -y
      Dump content: all pages
       Dump device: /dev/dsk/c0t1d0s1 (dedicated)
Savecore directory: /var/crash/pluto (minfree = 77071KB)
  Savecore enabled: yes