配置文件

默认的 /etc/kdump.conf 文件如下：

$ cat /etc/kdump.conf
# Configures where to put the kdump /proc/vmcore files
#
# This file contains a series of commands to perform (in order) when a
# kernel crash has happened and the kdump kernel has been loaded.  Directives in
# this file are only applicable to the kdump initramfs, and have no effect if
# the root filesystem is mounted and the normal init scripts are processed
#
# Currently only one dump target and path may be configured at a time. If dump
# to configured dump target fails, the default action will be preformed.
# Default action may be configured with the "default" directive below.
#
# Basics commands supported are:
# 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  
#			- 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 /usr/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.
#			  For ssh dump, scp should be used instead of cp.
#
# raw 	- Will write /proc/vmcore into raw [partition].
#
# nfs 	- Will mount fs and copy /proc/vmcore to
#			  [mnt]/[path]/%HOST-%DATE/, supports DNS.
#
# nfs4       - Will use NFSv4 instead of NFSv3
#
# net        - This is a deprecated option to transfer vmcore over
#			  nfs.  Use "nfs" option instead.
#
# ssh 	- Will copy /proc/vmcore to
#			  [user@server]:[path]/%HOST-%DATE/ via SSH,
#			  supports DNS. If makedumpfile is the core_collector,
#			  it is piped to an "ssh" shell, otherwise use the
#			  specified core_collector like scp.
#			  NOTE: make sure user has necessary write
#			  permissions on server
#
# net [user@server]     - This is a deprecated option to transfer vmcore over
#			  ssh.  Use "ssh" option instead.
#
# [fs type] [partition] - Will mount -t [fs type] [partition] /mnt and copy
#		 	  /proc/vmcore to /mnt/[path]/127.0.0.1-%DATE/.
#			  NOTE:  can be a device node, label or uuid.
#
# disk_timeout [seconds]
#			- Number of seconds to wait for disks to appear prior
#			  to continue to save dump. By default kdump waits
#			  180 seconds for the disks to show up it needs. This
#			  can be useful in some cases if disk never shows up
#			  (Either because disk was removed or because kdump is
#			  waiting on wrong disk).
#
# link_delay [seconds]
#			- Some network cards take a long time to initialize, and
#			  some spanning tree enabled networks do not transmit
#			  user traffic for long periods after a link state
#			  changes.  This optional parameter defines a wait
#			  period after a link is activated in which the
#			  initramfs will wait before attempting to transmit
#			  user data.
#
# 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.
#
# 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/halt the system
#
# 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.
# 			  Module name should be specified without ".ko" suffix.
#
# options [module] [option list]
#			- This directive allows you to specify options to apply
#			  to modules in the initramfs.  This directive overrides
#			  options specified in /etc/modprobe.conf. Module name
#			  should be specified without ".ko" suffix.
#
# blacklist [module]
#			- The blacklist keyword indicates that all of that
#			  particular modules are to be ignored in the initramfs.
#			  General terminology for blacklist has been that module
#			  is present in initramfs but it is not actually loaded
#			  in kernel. This directive can be specified multiple
#			  times or as a space separated list. Module name should
#			  be specified without ".ko" suffix.
#
# sshkey [path]
#			- Specifies the path of the ssh identity file you want
#			  to use when doing ssh dump. It must be a private key,
#			  the default value is /root/.ssh/kdump_id_rsa. When
#			  progagating public key, the key is assumed to be
#			  identity_file.pub which by default is
#			  /root/.ssh/kdump_id_rsa.pub.
#
# default [reboot | halt | poweroff | shell | mount_root_run_init]
#			- 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 and loose the core that you are
#				  trying to retrieve.
#			  halt:   If the default action is halt, then simply
#				  halt the system after attempting to capture
#				  a vmcore, regardless of success or failure.
#			  poweroff: The system will be powered down
#			  shell:  If the default action is shell, then drop to
#				  an hush session inside the initramfs from
#				  where you can try to record the core bananaally.
#				  Exiting this shell reboots the system.
#	     mount_root_run_init: Mount root filesystem and run init. Kdump
#			  	    initscript will try to save dump to root
#			  	    filesystem in /var/crash dir. This will
#			  	    likely require a lot more memory to
#			  	    be reserved for kdump kernel.
#
# debug_mem_level [0-3]
#                       - Turns on debug/verbose output of kdump scripts
#                         regarding free/used memory at various points of
#                         execution. Higher level means more debugging output.
#                         0 - no output
#                         1 - partial /proc/meminfo
#                         2 - /proc/meminfo
#                         3 - /proc/meminfo + /proc/slabinfo
#
# force_rebuild [0 | 1]
#			- By default, kdump initrd only will be rebuilt when
#			  necessary. Specify 1 here to force rebuilding kdump
#			  initrd every time when kdump service starts.
#
# fence_kdump_args [arg(s)]
#			- Command line arguments for fence_kdump_send (it can contain
#			all valid arguments except hosts to send notification to).
#
# fence_kdump_nodes [node(s)]
# 			- List of cluster node(s) separated by space to send fence_kdump
# 			notification to (this option is mandatory to enable fence_kdump).

#raw /dev/sda5
#ext4 /dev/sda3
#ext4 LABEL=/boot
#ext4 UUID=03138356-5e61-4ab3-b58e-27507ac41937
#net my.server.com:/export/tmp
#net user@my.server.com
path /var/crash
core_collector makedumpfile -c --message-level 1 -d 31
#core_collector scp
#core_collector cp --sparse=always
#extra_bins /bin/cp
#link_delay 60
#kdump_post /var/crash/scripts/kdump-post.sh
#extra_bins /usr/bin/lftp
#disk_timeout 30
#extra_modules gfs2
#options modulename options
#default shell
#debug_mem_level 0
#force_rebuild 1
#sshkey /root/.ssh/kdump_id_rsa
#fence_kdump_args -p 7410 -f auto -c 0 -i 10
#fence_kdump_nodes node1 node2

服务控制

要管理 kdump 服务以备将来关机和重启，请使用 chkconfig 工具：

# chkconfig kdump on
# chkconfig --list kdump
kdump           0:off   1:off   2:on    3:on    4:on    5:on    6:off

要立即控制 kdump 服务，请使用服务工具：

# service kdump
Usage: /etc/init.d/kdump {start|stop|status|restart|propagate}

# /etc/init.d/kdump start
Kdump already running                                      [  OK  ]

# /etc/init.d/kdump stop
Stopping kdump:                                            [  OK  ]

软件包名字：

kexec-tools-[version]-[arch].rpm
kexec-tools-2.0.0-310.el6.x86_64M

“kdump”服务说明

这是一个配置 kdump（内核转储）的脚本。
当内核出现严重问题时，Kdump 会将内存转储到名为 vmcore 的文件中。
通常需要 Vmcore 来调查该问题。
崩溃转储是从新启动的内核的上下文中捕获的，而不是从崩溃内核的上下文中捕获的。
每当系统崩溃时，Kdump 使用 kexec 引导到第二个内核。
Kexec 是一种快速启动机制，它允许从正在运行的内核的上下文中重新启动新的 Linux 内核，而无需通过任何固件或者热启动。