dumpadm man page on SunOS

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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] [-z on | off]

DESCRIPTION
       The  dumpadm program is an administrative command that manages the con‐
       figuration 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  mes‐
       sage describing the error is printed to the console. The operating sys‐
       tem then generates a crash dump by writing  the	contents  of  physical
       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 your file
       system in compressed form, to a file name vmdump.X, where X is an inte‐
       ger  identifying	 the  dump. Afterwards, savecore(1M) can be invoked on
       the same or another system to expand the compressed  crash  dump	 to  a
       pair  of	 files	named  unix.X and vmcore.X. The directory in which the
       crash dump is saved on reboot can be configured using dumpadm.

       For systems with a UFS root file system, the  default  dump  device  is
       configured  to  be  an  appropriate swap partition. Swap partitions are
       disk partitions reserved as virtual memory backing store for the	 oper‐
       ating  system.  Thus,  no  permanent  information resides in swap to be
       overwritten by the dump. See swap(1M). For systems with a ZFS root file
       system,	dedicated  ZFS	volumes	 are used for swap and dump areas. For
       further information about setting up a dump area with ZFS, see the  ZFS
       Administration  Guide.  To view the current dump configuration, use the
       dumpadm command with no arguments:

	 example# dumpadm

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

       When no options are specified, dumpadm displays the current crash  dump
       configuration.  The  example above 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. savecore is set to run automatically on reboot and
       save the crash dump in a compressed format.

       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 fol‐
	   lowing:

	   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 when the system is running a UFS root file
	       system.	   Or,	  specify    a	  ZFS	 volume,    such    as
	       /dev/zvol/dsk/rpool/dump, when the system is running a ZFS root
	       file system.

	   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 with a UFS root file system, dumpadm  uses  the
	       value  for swap to determine the initial dump device setting. A
	       given ZFS volume cannot be configured for both  the  swap  area
	       and the dump device.

       -m mink | minm | min%

	   Create  a minfree file in the current savecore directory indicating
	   that savecore should maintain at least the specified 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	 kilo‐
	       bytes.

	   m

	       A   positive  integer  suffixed	with  the  unit	 m  specifying
	       megabytes.

	   %

	       A % symbol, indicating that the minfree value  should  be  com‐
	       puted  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  adequate  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  configuration;  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 created prior to the execution of	savecore.  See
	   the	NOTES section below for a discussion of security issues relat‐
	   ing 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  set‐
	   tings from the previous boot must be restored. Your dump configura‐
	   tion is saved in the configuration file for this  purpose.  If  the
	   configuration  file	is  missing or contains invalid values for any
	   dump properties, the default values are substituted. Following  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.

       -z on | off

	   Modify  the dump configuration to control the operation of savecore
	   on reboot. The options are on, to enable saving  core  files	 in  a
	   compressed  format,	and off, to automatically uncompress the crash
	   dump file. The default is on, because crash dump files can be  very
	   large  and  require less file system space if saved in a compressed
	   format.

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
		 Save compressed: 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

	   Dump device.

       /etc/dumpadm.conf

	   Contains  configuration  parameters	for  dumpadm.  Modifiable only
	   through that command.

       savecore-directory/minfree

	   Contains minimum amount of free space for  savecore-directory.  See
	   savecore(1M).

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

       ┌─────────────────────────────┬─────────────────────────────┐
       │      ATTRIBUTE TYPE	     │	    ATTRIBUTE VALUE	   │
       ├─────────────────────────────┼─────────────────────────────┤
       │Availability		     │SUNWcs			   │
       └─────────────────────────────┴─────────────────────────────┘

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  service'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 (UFS File Systems Only)
       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
       displayed. Similarly, if the crash dump is disabled and the administra‐
       tor  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  sys‐
       tem subsequently changes size. In this case, the administrator 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 recom‐
       mended that alternate savecore directories also be created with similar
       permissions,  as	 the  operating system crash dump files themselves may
       contain secure information.

SunOS 5.10			  17 Aug 2009			   dumpadm(1M)
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