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- 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 . # # nfs - Will mount fs and copy /proc/vmcore to # / /%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 # : /%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 - This is a deprecated option to transfer vmcore over # ssh. Use "ssh" option instead. # # - Will mount -t /mnt and copy # /proc/vmcore to /mnt/ /127.0.0.1-%DATE/. # NOTE: can be a device node, label or uuid. # # disk_timeout # - 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 # - 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 # - 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 # - 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 # - 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 # - 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