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

       dumpadm - configure operating system crash dump

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

       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 re-

       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 in-
       valuable	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 re-
       trieve 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 in-
       teger 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  in-
       formation 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  re-

       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.

       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 exe-
					       cuting  on the CPU on which the
					       crash dump  was	initiated.  If
					       the  thread  executing  on that
					       CPU is a	kernel thread not  as-
					       sociated	with any user process,
					       only  kernel  pages   will   be

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

			       dump-device     A  specific  dump device	speci-
					       fied 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 con-
					       figure as the dump device.  See
					       swap(1M).  Refer	 to the	 NOTES
					       below for details of the	 algo-
					       rithm  used to select an	appro-
					       priate swap  entry.   When  the
					       system	is   first  installed,
					       dumpadm uses swap to  determine
					       the  initial  dump  device set-

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

			       k	       A   positive  integer  suffixed
					       with  the  unit	k   specifying

			       m	       A   positive  integer  suffixed
					       with  the  unit	m   specifying

			       %	       A % symbol, indicating that the
					       minfree value  should  be  com-
					       puted as	the specified percent-
					       age 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  de-
			       crease  the amount of free disk space below the
			       minfree threshold, no dump  files  are  written
			       and  an	error message is logged.  The adminis-
			       trator 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 di-
			       rectory 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 af-
			       ter boot, crash dump retrieval may not be  pos-

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

       -s savecore-dir	       Modify the dump configuration to	use the	speci-
			       fied   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  di-
			       rectory	is /var/crash/hostname where  hostname
			       is the output of	the -n option to the  uname(1)

       -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 pur-
			       pose.  If the configuration file	is missing  or
			       contains	 invalid  values  for any dump proper-
			       ties, the default values	are substituted.  Fol-
			       lowing  the  update,  the configuration file is
			       resynchronized with the kernel dump  configura-

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

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

       The  following command reconfigures the dump device to a	dedicated dump

       example#	dumpadm	-d /dev/dsk/c0t2d0s2

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

       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.




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

       |      ATTRIBUTE	TYPE	     |	    ATTRIBUTE VALUE	   |
       |Availability		     |SUNWcsr			   |

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

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


       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  en-
       tries  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 at-
       tempt 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  ap-
       propriate swap device is	added by the administrator, the	dump device is
       not changed; the	administrator must re-execute dumpadm -d swap to rese-
       lect 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			  25 Sep 2004			   dumpadm(1M)


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