KDUMP.CONF(5)							File Formats Manual						     KDUMP.CONF(5)

NAME

       kdump.conf - configuration file for kdump kernel.

DESCRIPTION

       kdump.conf is a configuration file for the kdump kernel crash collection service.

       kdump.conf  provides  post-kexec  instructions  to  the	kdump kernel. It is stored in the initrd file managed by the kdump service. If you
       change this file and do not want to restart before it takes effect, restart the kdump service to rebuild to initrd.

       For most configurations, you can simply review the examples provided in the stock /etc/kdump.conf.

       NOTE: For filesystem dump the dump target must be mounted before building kdump initramfs.

       kdump.conf only affects the behavior of the initramfs.  Please read the kdump operational flow section of kexec-kdump-howto.txt in the docs
       to better understand how this configuration file affects the behavior of kdump.

OPTIONS

       raw <partition>
	      Will dd /proc/vmcore into <partition>.  Use persistent device names for partition devices, such as /dev/vg/<devname>.

       nfs <nfs mount>
	      Will  mount  fs  and  copy /proc/vmcore to <mnt>/var/crash/%HOST-%DATE/, supports DNS. Note that a fqdn should be used as the server
	      name in the mount point

       ssh <user@server>
	      Will scp /proc/vmcore to <user@server>:/var/crash/%HOST-%DATE/, supports DNS. NOTE: make sure user has necessary	write  permissions
	      on server and that a fqdn is used as the server name

       sshkey <path>
	      Specifies the path of the ssh key you want to use when do ssh dump, the default value is /root/.ssh/kdump_id_rsa.

       <fs type> <partition>
	      Will  mount  -t  <fs type> <partition> /mnt and copy /proc/vmcore to /mnt/var/crash/%DATE/.  NOTE: <partition> can be a device node,
	      label or uuid.  It's recommended to use persistent device names such as /dev/vg/<devname>. Otherwise it's suggested to use label	or
	      uuid.

       path <path>
	      Append path to the filesystem device which you are dumping to.  Ignored for raw device dumps.  If unset, will default to /var/crash.

       core_collector <command> <options>
	      This  allows you to specify the command to copy the vmcore.  You could use the dump filtering program makedumpfile, the default one,
	      to retrieve your core, which on some arches can drastically reduce core file size.  See /sbin/makedumpfile  --help  for  a  list	of
	      options.	 Note  that  the  -i  and -g options are not needed here, as the initrd will automatically be populated with a config file
	      appropriate for the running kernel.

	      Note 1: About default core collector: Default core_collector for raw/ssh dump is: "makedumpfile -F  -l  --message-level  1  -d  31".
	      Default  core_collector for other targets is: "makedumpfile -l --message-level 1 -d 31".	Even if core_collector option is commented
	      out in kdump.conf, makedumpfile is default core collector and kdump uses it internally.	If  one  does  not  want  makedumpfile	as
	      default core_collector, then they need to specify one using core_collector option to change the behavior.

	      Note  2:	If  "makedumpfile  -F" is used then you will get a flattened format vmcore.flat, you will need to use "makedumpfile -R" to
	      rearrange the dump data from stdard input to a normal dumpfile (readable with  analysis  tools).	 ie.  "makedumpfile  -R  vmcore  <
	      vmcore.flat"

       kdump_post <binary | script>
	      This directive allows you to run a specified executable just after the memory dump process terminates. The exit status from the dump
	      process is fed to the kdump_post executable, which can be used to trigger different actions for success or failure.

	      Note that scripts written for use with this directive must use the /bin/bash interpreter

       kdump_pre <binary | script>
	      Works just like the kdump_post directive, but instead of running after the dump process, runs immediately before.   Exit	status	of
	      this binary is interpreted as follows:

	      0 - continue with dump process as usual

	      non 0 - reboot the system

	      Note that scripts written for this directive must use the /bin/bash interpreter

       extra_bins <binaries | shell scripts>
	      This directive allows you to specify additional binaries or shell scripts you'd like to include in your kdump initrd. Generally only
	      useful in conjunction with a kdump_post binary or script that relies on other binaries or scripts.

       extra_modules <module(s)>
	      This directive allows you to specify extra kernel modules that you want to be loaded in the kdump initrd, typically used to  set	up
	      access  to  non-boot-path  dump  targets	that  might  otherwise not be accessible in the kdump environment. Multiple modules can be
	      listed, separated by a space, and any dependent modules will automatically be included.

       default <reboot | halt | poweroff | shell | dump_to_rootfs>
	      Action to preform in case dumping to intended target fails. If no default action is specified, "reboot" is assumed default.  reboot:
	      If  the default action is reboot simply reboot the system (this is what most people will want, as it returns the system to a nominal
	      state).  shell: If the default action is shell, then drop to an shell session inside the initramfs from where you can manually  pre-
	      form  additional recovery actions.  Exiting this shell reboots the system.  halt: bring the system to a halt, requiring manual reset
	      poweroff: The system will be powered down. dump_to_rootfs:If the default action is dump_to_rootfs, specified root  will  be  mounted
	      and dump will be saved in "path" directory.  Note: kdump uses bash as the default shell.

       force_rebuild <0 | 1>
	      By default, kdump initrd only will be rebuilt when necessary.  Specify 1 to force rebuilding kdump initrd every time when kdump ser-
	      vice starts.

       override_resettable <0 | 1>
	      Usually a unresettable block device can't be dump target. Specifying 1 means though block target is  unresettable,  user	understand
	      this situation and want to try dumping. By default, it's set to 0, means not to try a destined failure.

       dracut_args <arg(s)>
	      Kdump uses dracut to generate initramfs for second kernel. This option allows a user to pass arguments to dracut directly.

DEPRECATED OPTIONS

       net <nfs mount>|<user@server>
	      net option is replaced by nfs and ssh options. Use nfs or ssh options directly.

       options <module> <option list>
	      Use  KDUMP_COMMANDLINE_APPEND  in  /etc/sysconfig/kdump  to  add	proper module option as kernel command line params. Such as append
	      loop.max_loop=1 to limit maximum loop devices to 1.

       link_delay <seconds>
	      link_delay was used to wait a network device to initialize before using it.  Now dracut network module take care of this issue auto-
	      maticlly.

       disk_timeout <seconds>
	      Similar to link_delay, dracut ensures disks being ready before kdump uses them.

       debug_mem_level <0-3>
	      This  was  used  to  turns on debug/verbose output of kdump scripts regarding free/used memory at various points of execution.  This
	      feature has been moved to dracut now.   Use  KDUMP_COMMANDLINE_APPEND  in  /etc/sysconfig/kdump  and  append  dracut  cmdline  param
	      rd.memdebug=[0-3] to enable the debug output.

	      Higher level means more debugging output.

	      0 - no output

	      1 - partial /proc/meminfo

	      2 - /proc/meminfo

	      3 - /proc/meminfo + /proc/slabinfo

       blacklist <list of kernel modules>
	      blacklist  option  was  recently being used to prevent loading modules in initramfs. General terminology for blacklist has been that
	      module is present in initramfs but it is not actually loaded in kernel. Hence retaining  blacklist  option  creates  more  confusing
	      behavior. It has been deprecated.

	      Instead  use  rd.driver.blacklist  option on second kernel to blacklist a certain module. One can edit /etc/sysconfig/kdump.conf and
	      edit KDUMP_COMMANDLINE_APPEND to pass kernel command line options. Refer to dracut.cmdline man  page  for  more  details	on  module
	      blacklist option.

EXAMPLES

       Here is some examples for core_collector option:

       Core  collector command format depends on dump target type. Typically for filesystem (local/remote), core_collector should accept two argu-
       ments.  First one is source file and second one is target file. For ex.

       ex1.   core_collector "cp --sparse=always"

	      Above will effectively be translated to:

	      cp --sparse=always /proc/vmcore <dest-path>/vmcore

       ex2.   core_collector "makedumpfile -l --message-level 1 -d 31"

	      Above will effectively be translated to:

	      makedumpfile -l --message-level 1 -d 31 /proc/vmcore <dest-path>/vmcore

       For dump targets like raw and ssh, in general, core collector should expect one argument (source file) and should output the processed core
       on  standard output (There is one exception of "scp", discussed later). This standard output will be saved to destination using appropriate
       commands.

       raw dumps examples:

       ex3.   core_collector "cat"

	      Above will effectively be translated to.

	      cat /proc/vmcore | dd of=<target-device>

       ex4.   core_collector "makedumpfile -F -l --message-level 1 -d 31"

	      Above will effectively be translated to.

	      makedumpfile -F -l --message-level 1 -d 31 | dd of=<target-device>

       ssh dumps examples

       ex5.   core_collector "cat"

	      Above will effectively be translated to.

	      cat /proc/vmcore | ssh <options> <remote-location> "dd of=path/vmcore"

       ex6.   core_collector "makedumpfile -F -l --message-level 1 -d 31"

	      Above will effectively be translated to.

	      makedumpfile -F -l --message-level 1 -d 31 | ssh <options> <remote-location> "dd of=path/vmcore"

	      There is one exception to standard output rule for ssh dumps. And that is scp. As scp can handle ssh destinations  for  file  trans-
	      fers, one can specify "scp" as core collector for ssh targets (no output on stdout).

       ex7.   core_collector "scp"

	      Above will effectively be translated to.

	      scp /proc/vmcore <user@host>:path/vmcore

       examples for other options please see /etc/kdump.conf

SEE ALSO

       kexec(8) mkdumprd(8) dracut.cmdline(7)

kexec-tools							    07/23/2008							     KDUMP.CONF(5)