The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.
During installation, you are given the option of enabling Kdump and specifying the amount of memory to reserve for it. If you prefer, you can enable kdump at a later time as described in this section.
If the kexec-tools
and
system-config-kdump
packages are not already
installed on your system, use yum to install
them.
To enable Kdump by using the Kernel Dump Configuration GUI.
Enter the following command.
#
system-config-kdump
The Kernel Dump Configuration GUI starts. If Kdump is currently disabled, the green Enable button is selectable and the Disable button is greyed out.
Click Enable to enable Kdump.
You can select the following settings tags to adjust the configuration of Kdump.
- Basic Settings
Allows you to specify the amount of memory to reserve for Kdump. The default setting is 128 MB.
- Target Settings
Allows you to specify the target location for the
vmcore
dump file on a locally accessible file system, to a raw disk device, or to a remote directory using NFS or SSH over IPv4. The default location is/var/crash
.You cannot save a dump file on an eCryptfs file system, on remote directories that are NFS mounted on the
rootfs
file system, or on remote directories that access require the use of IPv6, SMB, CIFS, FCoE, wireless NICs, multipathed storage, or iSCSI over software initiators to access them.- Filtering Settings
Allows to select which type of data to include in or exclude from the dump file. Selecting or deselecting the options alters the value of the argument that Kdump specifies to the -d option of the core collector program, makedumpfile.
- Expert Settings
Allows you to choose which kernel to use, edit the command line options that are passed to the kernel and the core collector program, choose the default action if the dump fails, and modify the options to the core collector program, makedumpfile.
For example, if Kdump fails to start, and the following error appears in
/var/log/messages
, set the offset for the reserved memory to 48 MB or greater in the command line options, for examplecrashkernel=128M@48M
:kdump: No crashkernel parameter specified for running kernel
The Unbreakable Enterprise Kernel supports the use of the
crashkernel=auto
setting for UEK Release 3 Quarterly Update 1 and later. If you use thecrashkernel=auto
setting, the output of the dmesg command showscrashkernel=XM@0M
, which is normal. The setting actually reserves 128 MB plus 64 MB for each terabyte of physical memory.NoteYou cannot configure
crashkernel=auto
for Xen or for the UEK prior to UEK Release 3 Quarterly Update 1. Only standard settings such ascrashkernel=128M@48M
are supported. For systems with more than 128 GB of memory, the recommended setting iscrashkernel=512M@64M
.You can select one of five default actions should the dump fail:
- mount rootfs and run /sbin/init
Mount the root file system and run
init
. The/etc/init.d/kdump
script attempts to save the dump to/var/crash
, which requires a large amount of memory to be reserved.- reboot
Reboot the system, losing the
vmcore
. This is the default action.- shell
Enter a shell session inside the
initramfs
so that you can attempt to record the core. To reboot the system, exit the shell.- halt
Halt the system.
- poweroff
Power down the system.
Click Help for more information on these settings.
Click Apply to save your changes. The GUI displays a popup message to remind you that you must reboot the system for the changes to take effect.
Click OK to dismiss the popup messages.
Select File > Quit.
Reboot the system at a suitable time.