dumpadm man page on SmartOS

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DUMPADM(1M)							   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] [-z on | off]

       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

       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 the file
       system. The directory in which the crash dump is saved  on  reboot  can
       also be configured using dumpadm.

       When the operating system takes a crash dump the default behavior is to
       compress the crash dump. This behavior is controlled by the -z  option.
       When compression is turned on, the savecore(1M) utility writes one file
       to the file system named	 vmdump.X.  If	compression  is	 disabled,  it
       instead writes two files named unix.X and vmcore.X. In the uncompressed
       case, both data files form the saved crash dump. In both cases X is  an
       integer identifying the dump.

       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: on

       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,  savecore  is  set to run automatically on reboot,
       and compression is turned on.

       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  fol‐


	       Kernel memory pages only.


	       All memory pages.


	       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 be one of the following:


	       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.


	       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.


	       If the special token none is specified, the active dump	device
	       is removed and crash dumps are disabled.

       -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:


	       A positive integer suffixed with the unit  k  specifying	 kilo‐


	       A   positive  integer  suffixed	with  the  unit	 m  specifying


	       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.


	   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.


	   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.


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

       -z on | off

	   Turns crash dump compression on or off.

       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
		 Save compressed: on

       The following exit values are returned:


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


	   A  fatal  error  occurred in either obtaining or modifying the dump


	   Invalid command line options were specified.


	   Dump device.


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


	   Contains  minimum  amount of free space for savecore-directory. See

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

       The  system  crash  dump	 service  is managed by the service management
       facility, 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 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 adminis‐
       trator 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

       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.

				 Feb 15, 2013			   DUMPADM(1M)

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