System information
kexec and kdump 209
18.6 Basic kdump Configuration
You can use kdump to save kernel dumps. If the kernel crashes, it is useful to copy
the memory image of the crashed environment to the file system. You can then debug
the dump file to find the cause of the kernel crash. This is called “core dump”.
kdump works similar to kexec (see Chapter18, kexec and kdump (page205)). The
capture kernel is executed after the running production kernel crashes. The difference
is that kexec replaces the production kernel with the capture kernel. With kdump, you
still have access to the memory space of the crashed production kernel. You can save
the memory snapshot of the crashed kernel in the environment of the kdump kernel.
TIP: Dumps over Network
In environments with limited local storage, you need to set up kernel dumps
over the network. kdump supports configuring the specified network inter-
face and bringing it up via initrd. Both LAN and VLAN interfaces are sup-
ported. You have to specify the network interface and the mode (dhcp or sta-
tic) either with YaST, or using the KDUMP_NETCONFIG option in the /etc/
sysconfig/kdump file. The third way is to build initrd manually, for ex-
ample with
/sbin/mkinitrd -D vlan0
for a dhcp VLAN interface, or
/sbin/mkinitrd -I eth0
for a static LAN interface.
You can either configure kdump manually or with YaST.
IMPORTANT: Target Filesystem for kdump Must Be Mounted During
Configuration
When configuring kdump, you can specify a location to which the dumped
images will be saved (default: /var/crash). This location must be mounted
when configuring kdump, otherwise the configuration will fail.