This is a script which configures kdump (kernel dump). Kdump provides a memory dump into a file named vmcore when the kernel has a critical issue. Vmcore is often required to investigate the issue. The crash dump is captured from the context of a freshly-booted kernel, not from the context of the crashed kernel. Kdump uses kexec to boot into a second kernel whenever the system crashes. Kexec is a fast-boot mechanism which allows rebooting a new Linux kernel from the context of a running kernel without going through any firmware or warm start.
Service Control
To manage the kdump service for future shutdowns and reboots, use the chkconfig tool:
# chkconfig kdump on # chkconfig --list kdump kdump 0:off 1:off 2:on 3:on 4:on 5:on 6:off
To control the kdump service immediately, use the service tool:
# 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 ]
Package name:
kexec-tools-[version]-[arch].rpm kexec-tools-2.0.0-310.el6.x86_64M
Configuration files
The default /etc/kdump.conf file is given below:
$ 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 manually. # 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