dumpadm(1M)                                               System Administration Commands                                               dumpadm(1M)

NAME

       dumpadm - configure operating system crash dump

SYNOPSIS

       /usr/sbin/dumpadm [-nuy] [-c content-type] [-d dump-device] [-m mink | minm  |  min%]  [-s savecore-dir] [-r root-dir]

DESCRIPTION

       The  dumpadm program is an administrative command that manages the configuration of the operating system crash dump facility.  A crash dump
       is a disk copy of the physical memory of the computer at the time of a fatal system error. When a fatal operating system  error  occurs,  a
       message  describing the error is printed to the console. The operating system then generates a crash dump by writing the contents of physi-
       cal memory to a predetermined dump device, which is typically a local disk partition.  The dump device can be configured by way of dumpadm.
       Once the crash dump has been written to the dump device, the system will reboot.

       Fatal  operating  system  errors  can  be caused by bugs in the operating system, its associated device drivers and loadable modules, or by
       faulty hardware. Whatever the cause, the crash dump itself provides invaluable information to your support engineer to  aid  in  diagnosing
       the  problem.   As  such,  it  is  vital that the crash dump be retrieved and given to your support provider. Following an operating system
       crash, the savecore(1M) utility is executed automatically during boot to retrieve the crash dump from the dump device, and write  it  to  a
       pair  of  files  in your file system named unix.X and vmcore.X, where X is an integer identifying the dump. Together, these data files form
       the saved crash dump. The directory in which the crash dump is saved on reboot can also be configured using dumpadm.

       By default, the dump device is configured to be an appropriate swap partition. Swap partitions are disk partitions reserved as virtual mem-
       ory backing store for the operating system, and thus no permanent information resides there to be overwritten by the dump. See swap(1M). To
       view the current dump configuration, execute dumpadm with no arguments:

       example# dumpadm

             Dump content: kernel pages
              Dump device: /dev/dsk/c0t0d0s1 (swap)
       Savecore directory: /var/crash/saturn
         Savecore enabled: yes

       When no options are specified, dumpadm prints the current crash dump configuration.  The example shows the set of default values: the  dump
       content  is  set  to  kernel  memory  pages  only,  the  dump  device  is a swap disk partition, the directory for savecore files is set to
       /var/crash/hostname, and savecore is set to run automatically on reboot.

       When one or more options are specified, dumpadm verifies that your changes are valid, and if so, reconfigures the crash dump parameters and
       displays the resulting configuration. You must be root to view or change dump parameters.

OPTIONS

       The following options are supported:

       -c content-type         Modify the dump configuration so that the crash dump consists of the specified dump content.  The content should be
                               one of the following:

                               kernel          Kernel memory pages only.

                               all             All memory pages.

                               curproc         Kernel memory pages, and the memory pages of the process whose thread was  currently  executing  on
                                               the  CPU  on  which  the  crash dump was initiated. If the thread executing on that CPU is a kernel
                                               thread not associated with any user process, only kernel pages will be dumped.

       -d  dump-device         Modify the dump configuration to use the specified dump device. The dump device may one of the following:

                               dump-device     A specific dump device specified as an absolute pathname, such as /dev/dsk/ cNtNdNsN.

                               swap            If the special token swap is specified as the dump device, dumpadm examines the active swap entries
                                               and  selects  the most appropriate entry  to configure as the dump device.  See  swap(1M). Refer to
                                               the  NOTES  below for details of the algorithm used to select an appropriate swap entry.  When  the
                                               system is first installed, dumpadm uses swap to determine the initial dump device setting.

       -m mink | minm | min%   Create a minfree file in the current savecore directory indicating that savecore should maintain at least the spec-
                               ified amount of free space in the file system where the savecore directory is located.  The min argument can be one
                               of the following:

                               k               A positive integer suffixed with the unit k specifying kilobytes.

                               m               A positive integer suffixed with the unit m specifying megabytes.

                               %               A % symbol, indicating that the minfree value should be computed as the specified percentage of the
                                               total current size of the file system containing the savecore directory.

                               The savecore command will consult the minfree file, if present, prior to writing the dump files.  If  the  size  of
                               these files would decrease the amount of free disk space below the minfree threshold, no dump files are written and
                               an error message is logged.  The administrator should immediately clean up the savecore directory to  provide  ade-
                               quate  free  space,  and re-execute the savecore command manually.  The administrator can also specify an alternate
                               directory on the savecore command-line.

       -n                      Modify the dump configuration to not run savecore automatically on reboot.  This is not the recommended system con-
                               figuration; if the dump device is a swap partition, the dump data will be overwritten as the system begins to swap.
                               If savecore is not executed shortly after boot, crash dump retrieval may not be possible.

       -r root-dir             Specify an alternate root directory relative to which dumpadm should create files.  If no -r argument is specified,
                               the default root directory "/" is used.

       -s savecore-dir         Modify  the  dump  configuration  to  use  the specified directory to save files written by savecore. The directory
                               should be an absolute path and exist on the system.  If upon reboot the directory does not exist, it will  be  cre-
                               ated  prior to the execution of savecore. See the  NOTES section below for a discussion of security issues relating
                               to access to the savecore directory.  The default savecore directory is /var/crash/hostname where  hostname is  the
                               output of the -n option to the uname(1) command.

       -u                      Forcibly  update  the kernel dump configuration based on the contents of /etc/dumpadm.conf. Normally this option is
                               used only on reboot when starting svc:/system/dumpadm:default, when the dumpadm settings  from  the  previous  boot
                               must  be restored.  Your dump configuration is saved in the configuration file for this purpose.  If the configura-
                               tion file is missing or contains invalid values for any dump properties, the default values are substituted.   Fol-
                               lowing the update, the configuration file is resynchronized with the kernel dump configuration.

       -y                      Modify the dump configuration to automatically run savecore on reboot.  This is the default for this dump setting.

EXAMPLES

       Example 1: Reconfiguring The Dump Device To A Dedicated Dump Device:

       The following command reconfigures the dump device to a dedicated dump device:

       example# dumpadm -d /dev/dsk/c0t2d0s2

                  Dump content: kernel pages
                   Dump device: /dev/dsk/c0t2d0s2 (dedicated)
            Savecore directory: /var/crash/saturn
              Savecore enabled: yes

EXIT STATUS

       The following exit values are returned:

       0        Dump configuration is valid and the specified modifications, if any, were made successfully.

       1        A fatal error occurred in either obtaining or modifying the dump configuration.

       2        Invalid command line options were specified.

FILES

       /dev/dump

       /etc/dumpadm.conf

       savecore-directory/minfree

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Availability                 |SUNWcsr                      |
       +-----------------------------+-----------------------------+

SEE ALSO

       svcs(1), uname(1), savecore(1M), svcadm(1M), swap(1M), attributes(5), smf(5)

NOTES

       The system crash dump service is managed by the service management facility, smf(5), under the service identifier:

       svc:/system/dumpadm:default

       Administrative  actions  on  this  service, such as enabling, disabling, or requesting restart, can be performed using svcadm(1M). The ser-
       vice's status can be queried using the svcs(1) command.

   Dump Device Selection
       When the special swap token is specified as the argument to dumpadm -d the utility will attempt to  configure  the  most  appropriate  swap
       device as the dump device. dumpadm configures the largest swap block device as the dump device; if no block devices are available for swap,
       the largest swap entry is configured as the dump device.  If no swap entries are present, or none can be configured as the dump  device,  a
       warning message will be displayed.  While local and remote swap files can be configured as the dump device, this is not recommended.

   Dump Device/Swap Device Interaction
       In the event that the dump device is also a swap device, and the swap device is deleted by the administrator using the swap -d command, the
       swap command will automatically invoke dumpadm -d swap in order to attempt to configure another appropriate swap device as the dump device.
       If  no swap devices remain or none can be configured as the dump device, the crash dump will be disabled and a warning message will be dis-
       played.  Similarly, if the crash dump is disabled and the administrator adds a new swap device using the  swap -a command, dumpadm -d  swap
       will be invoked to re-enable the crash dump using the new swap device.

       Once  dumpadm  -d swap has been issued, the new dump device is stored in the configuration file for subsequent reboots. If a larger or more
       appropriate swap device is added by the administrator, the dump device is not changed; the administrator must re-execute dumpadm -d swap to
       reselect the most appropriate device fom the new list of swap devices.

   Minimum Free Space
       If  the  dumpadm  -m  option  is  used  to  create a minfree file based on a percentage of the total size of the file system containing the
       savecore directory, this value is not automatically recomputed if the file system subsequently changes size.  In this case, the administra-
       tor  must re-execute dumpadm -m to recompute the minfree value.  If no such file exists in the savecore directory, savecore will default to
       a free space threshold of one megabyte.  If no free space threshold is desired, a minfree file containing size 0 can be created.

   Security Issues
       If, upon reboot, the specified savecore directory is not present, it will be created prior to the execution of  savecore  with  permissions
       0700  (read, write, execute by owner only) and owner root. It is recommended that alternate savecore directories also be created with simi-
       lar permissions, as the operating system crash dump files themselves may contain secure information.

SunOS 5.10                                                          25 Sep 2004                                                        dumpadm(1M)