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.TH KDUMP.CONF 5 "07/23/2008" "kexec-tools"
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.SH NAME
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kdump.conf \- configuration file for kdump kernel.
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.SH DESCRIPTION 
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kdump.conf is a configuration file for the kdump kernel crash
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collection service.
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kdump.conf provides post-kexec instructions to the kdump kernel. It is
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stored in the initrd file managed by the kdump service. If you change
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this file and do not want to reboot in order for the changes to take
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effect, restart the kdump service to rebuild the initrd.
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For most configurations, you can simply review the examples provided
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in the stock /etc/kdump.conf.
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.B NOTE: 
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For filesystem dumps the dump target must be mounted before building
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kdump initramfs.
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kdump.conf only affects the behavior of the initramfs.  Please read the
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kdump operational flow section of kexec-kdump-howto.txt in the docs to better
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understand how this configuration file affects the behavior of kdump.
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.SH OPTIONS
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.B auto_reset_crashkernel <yes|no>
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.RS
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determine whether to reset kernel crashkernel to new default value
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or not when kexec-tools updates the default crashkernel value and
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existing kernels using the old default kernel crashkernel value
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.B raw <partition>
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.RS
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Will dd /proc/vmcore into <partition>.  Use persistent device names for
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partition devices, such as /dev/vg/<devname>.
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.RE
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.B nfs <nfs mount>
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.RS
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Will mount nfs to <mnt>, and copy /proc/vmcore to <mnt>/<path>/%HOST-%DATE/,
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supports DNS. Note that a fqdn should be used as the server name in the 
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mount point.
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.RE
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.B ssh <user@server>
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.RS
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Will save /proc/vmcore through ssh pipe to <user@server>:<path>/%HOST-%DATE/,
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supports DNS. NOTE: make sure user has necessary write permissions on
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server and that a fqdn is used as the server name.
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.RE
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.B sshkey <path>
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.RS
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Specify the path of the ssh key to use when dumping via ssh.
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The default value is /root/.ssh/kdump_id_rsa.
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.RE
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.B <fs type> <partition>
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.RS
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Will mount -t <fs type> <partition> <mnt>, and copy /proc/vmcore to
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<mnt>/<path>/%HOST_IP-%DATE/.  NOTE: <partition> can be a device node, label
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or uuid.  It's recommended to use persistent device names such as
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/dev/vg/<devname>.  Otherwise it's suggested to use label or uuid.
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.RE
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.B path <path>
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.RS
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"path" represents the file system path in which vmcore will be saved.
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If a dump target is specified in kdump.conf, then "path" is relative to the
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specified dump target.
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.PP
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Interpretation of "path" changes a bit if the user didn't specify any dump
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target explicitly in kdump.conf. In this case, "path" represents the
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absolute path from root.  The dump target and adjusted path are arrived
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at automatically depending on what's mounted in the current system.
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.PP
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Ignored for raw device dumps.  If unset, will use the default "/var/crash".
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.RE
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.B core_collector <command> <options>
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.RS
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This allows you to specify the command to copy the vmcore.
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The default is makedumpfile, which on some architectures can drastically reduce
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core file size. See /sbin/makedumpfile --help for a list of options.
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Note that the -i and -g options are not needed here, as the initrd
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will automatically be populated with a config file appropriate
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for the running kernel.
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.PP
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Note 1: About default core collector:
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The default core_collector for raw/ssh dump is:
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"makedumpfile -F -l --message-level 7 -d 31".
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The default core_collector for other targets is:
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"makedumpfile -l --message-level 7 -d 31".
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Even if core_collector option is commented out in kdump.conf, makedumpfile
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is the default core collector and kdump uses it internally.
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If one does not want makedumpfile as default core_collector, then they
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need to specify one using core_collector option to change the behavior.
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.PP
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Note 2: If "makedumpfile -F" is used then you will get a flattened format
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vmcore.flat, you will need to use "makedumpfile -R" to rearrange the
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dump data from standard input to a normal dumpfile (readable with analysis
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tools).
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ie. "makedumpfile -R vmcore < vmcore.flat"
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Note 3: If specified core_collector simply copy the vmcore file to the
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dump target (eg: cp, scp), the vmcore could be significantly large.
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Please make sure the dump target has enough space, at leaset larger
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than the system's RAM.
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.RE
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.B kdump_post <binary | script>
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.RS
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This directive allows you to run a specified executable
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just after the vmcore dump process terminates.  The exit
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status of the current dump process is fed to the kdump_post
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executable as its first argument($1).  Executable can modify
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it to indicate the new exit status of succeeding dump process,
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.PP
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All files under /etc/kdump/post.d are collectively sorted
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and executed in lexical order, before binary or script
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specified kdump_post parameter is executed.
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.PP
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Note that scripts written for use with this directive must use the /bin/bash
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interpreter. And since these scripts run in kdump enviroment, the reference to
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the storage or network device in the scripts should adhere to the section
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'Supported dump target types and requirements' in kexec-kdump-howto.txt.
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.RE
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.B kdump_pre <binary | script>
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.RS
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Works just like the "kdump_post" directive, but instead
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of running after the dump process, runs immediately
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before.  Exit status of this binary is interpreted
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as follows:
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.PP
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0 - continue with dump process as usual
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.PP
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non 0 - run the final action (reboot/poweroff/halt)
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.PP
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All files under /etc/kdump/pre.d are collectively sorted and
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executed in lexical order, after binary or script specified
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kdump_pre parameter is executed.
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Even if the binary or script in /etc/kdump/pre.d directory
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returns non 0 exit status, the processing is continued.
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.PP
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Note that scripts written for use with this directive must use the /bin/bash
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interpreter. And since these scripts run in kdump enviroment, the reference to
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the storage or network device in the scripts should adhere to the section
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'Supported dump target types and requirements' in kexec-kdump-howto.txt.
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.RE
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.B extra_bins <binaries | shell scripts>
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.RS
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This directive allows you to specify additional
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binaries or shell scripts you'd like to include in
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your kdump initrd. Generally only useful in
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conjunction with a kdump_post binary or script that
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relies on other binaries or scripts.
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.RE
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.B extra_modules <module(s)>
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.RS
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This directive allows you to specify extra kernel
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modules that you want to be loaded in the kdump
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initrd, typically used to set up access to
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non-boot-path dump targets that might otherwise
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not be accessible in the kdump environment. Multiple
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modules can be listed, separated by spaces, and any
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dependent modules will automatically be included.
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.RE
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.B failure_action <reboot | halt | poweroff | shell | dump_to_rootfs>
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.RS
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Action to perform in case dumping to the intended target fails. The default is "reboot".
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reboot: Reboot the system (this is what most people will want, as it returns the system
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to a normal state).  halt: Halt the system and lose the vmcore.  poweroff: The system
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will be powered down.  shell: Drop to a shell session inside the initramfs, from which
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you can manually perform additional recovery actions.  Exiting this shell reboots the
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system by default or performs "final_action".
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Note: kdump uses bash as the default shell.  dump_to_rootfs: If non-root dump
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target is specified, the failure action can be set as dump_to_rootfs.  That means when
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dumping to target fails, dump vmcore to rootfs from initramfs context and reboot
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by default or perform "final_action".
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.RE
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.B default <reboot | halt | poweroff | shell | dump_to_rootfs>
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.RS
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Same as the "failure_action" directive above, but this directive is obsolete
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and will be removed in the future.
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.RE
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.B final_action <reboot | halt | poweroff>
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.RS
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Action to perform in case dumping to the intended target succeeds.
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Also performed when "shell" or "dump_to_rootfs" failure action finishes.
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Each action is same as the "failure_action" directive above.
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The default is "reboot".
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.RE
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.B force_rebuild <0 | 1>
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.RS
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By default, kdump initrd will only be rebuilt when necessary.
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Specify 1 to force rebuilding kdump initrd every time when kdump service starts.
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.RE
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.B force_no_rebuild <0 | 1>
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.RS
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By default, kdump initrd will be rebuilt when necessary.
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Specify 1 to bypass rebuilding of kdump initrd.
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.PP
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force_no_rebuild and force_rebuild options are mutually exclusive and
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they should not be set to 1 simultaneously.
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.RE
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.B override_resettable <0 | 1>
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.RS
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Usually an unresettable block device can't be a dump target. Specifying 1 means
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that even though the block target is unresettable, the user wants to try dumping anyway.
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By default, it's set to 0, which will not try something destined to fail.
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.RE
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.B dracut_args <arg(s)>
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.RS
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Kdump uses dracut to generate initramfs for second kernel. This option
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allows a user to pass arguments to dracut directly.
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.RE
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.B fence_kdump_args <arg(s)>
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.RS
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Command line arguments for fence_kdump_send (it can contain all valid
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arguments except hosts to send notification to).
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.RE
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.B fence_kdump_nodes <node(s)>
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.RS
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List of cluster node(s) except localhost, separated by spaces, to send fence_kdump notification
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to (this option is mandatory to enable fence_kdump).
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.RE
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.SH DEPRECATED OPTIONS
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.B net <nfs mount>|<user@server>
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.RS
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net option is replaced by nfs and ssh options. Use nfs or ssh options
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directly.
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.RE
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.B options <module> <option list>
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.RS
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Use KDUMP_COMMANDLINE_APPEND in /etc/sysconfig/kdump to add module options as
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kernel command line parameters. For example, specify 'loop.max_loop=1' to limit
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maximum loop devices to 1.
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.RE
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.B link_delay <seconds>
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.RS
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link_delay was used to wait for a network device to initialize before using it.
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Now dracut network module takes care of this issue automatically.
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.RE
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.B disk_timeout <seconds>
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.RS
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Similar to link_delay, dracut ensures disks are ready before kdump uses them.
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.RE
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.B debug_mem_level <0-3>
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.RS
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Turn on verbose debug output of kdump scripts regarding free/used memory at
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various points of execution.  This feature has been
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moved to dracut now.
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Use KDUMP_COMMANDLINE_APPEND in /etc/sysconfig/kdump and
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append dracut cmdline param rd.memdebug=[0-3] to enable the debug output.
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Higher level means more debugging output.
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0 - no output
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1 - partial /proc/meminfo
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.PP
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2 - /proc/meminfo
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.PP
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3 - /proc/meminfo + /proc/slabinfo
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.RE
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.B blacklist <list of kernel modules>
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.RS
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blacklist option was recently being used to prevent loading modules in
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initramfs. General terminology for blacklist has been that module is
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present in initramfs but it is not actually loaded in kernel. Hence
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retaining blacklist option creates more confusing behavior. It has been
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deprecated.
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.PP
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Instead, use rd.driver.blacklist option on second kernel to blacklist
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a certain module. One can edit /etc/sysconfig/kdump.conf and edit
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KDUMP_COMMANDLINE_APPEND to pass kernel command line options. Refer
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to dracut.cmdline man page for more details on module blacklist option.
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.RE
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.RE
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.SH EXAMPLES
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Here are some examples for core_collector option:
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.PP
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Core collector command format depends on dump target type. Typically for
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filesystem (local/remote), core_collector should accept two arguments.
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First one is source file and second one is target file. For ex.
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.TP
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ex1.
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core_collector "cp --sparse=always"
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Above will effectively be translated to:
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cp --sparse=always /proc/vmcore <dest-path>/vmcore
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.TP
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ex2.
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core_collector "makedumpfile -l --message-level 7 -d 31"
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Above will effectively be translated to:
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makedumpfile -l --message-level 7 -d 31 /proc/vmcore <dest-path>/vmcore
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.PP
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For dump targets like raw and ssh, in general, core collector should expect
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one argument (source file) and should output the processed core on standard
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output (There is one exception of "scp", discussed later). This standard
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output will be saved to destination using appropriate commands.
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raw dumps examples:
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.TP
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ex3.
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core_collector "cat"
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Above will effectively be translated to.
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cat /proc/vmcore | dd of=<target-device>
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.TP
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ex4.
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core_collector "makedumpfile -F -l --message-level 7 -d 31"
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Above will effectively be translated to.
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makedumpfile -F -l --message-level 7 -d 31 | dd of=<target-device>
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.PP
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ssh dumps examples
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.TP
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ex5.
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core_collector "cat"
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Above will effectively be translated to.
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cat /proc/vmcore | ssh <options> <remote-location> "dd of=path/vmcore"
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.TP
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ex6.
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core_collector "makedumpfile -F -l --message-level 7 -d 31"
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Above will effectively be translated to.
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makedumpfile -F -l --message-level 7 -d 31 | ssh <options> <remote-location> "dd of=path/vmcore"
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There is one exception to standard output rule for ssh dumps. And that is
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scp. As scp can handle ssh destinations for file transfers, one can
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specify "scp" as core collector for ssh targets (no output on stdout).
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.TP
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ex7.
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core_collector "scp"
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Above will effectively be translated to.
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scp /proc/vmcore <user@host>:path/vmcore
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.PP
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examples for other options please see
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.I /etc/kdump.conf
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.SH SEE ALSO
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kexec(8) mkdumprd(8) dracut.cmdline(7)