Configuration of fadump

This document (7012786) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11 Service Pack 3 (SLES 11 SP3)
SUSE Linux Enterprise Server 11 Service Pack 4 (SLES 11 SP4)

Situation

On SLES11 SP3 and SP4 there is no YaST2 module available to setup firmware assisted dump (fadump).

It has to be enabled / disabled manually as described with this document.

Resolution

Prerequisites:

The kernel to be configured with fadump must be the default boot entry.

Boot into the kernel to be configured with fadump before running the steps to enable/disable fadump.

Install the latest available makedumpfile, kexec-tools & kdump packages.

To enable fadump do the following:

1. Enable boot.kdump service

chkconfig boot.kdump on

2. In /etc/sysconfig/kdump set:

KDUMP_FADUMP=yes

3. As user root run the below command to add dump capturing support in initrd:

mkdumprd -f

4. Refresh bootloader to use the new initrd for all subsequent boots:

update-bootloader --refresh

5. Reboot the system

6. After a reboot verify with the below that this file is available and shows a value of '1':

cat /sys/kernel/fadump_registered

This indicates that fadump is enabled in the kernel and the system will now use the fadump mechanism to capture a kernel dump.

NOTE:

If after this process the file /etc/sysconfig/kdump is modified again by any means, be it manually or via YaST, the below command has to be run again, to make fadump aware of these changes:

mkdumprd -f

If a new kernel is installed after fadump was configured on a previous installed kernel, boot into the new kernel and execute Steps 3 to 5 to configure fadump support for the new kernel.

To disable fadump do the following:

1. In /etc/sysconfig/kdump set

KDUMP_FADUMP=no

2. As user root run the below command to update the kernel cmdline parameters:

mkdumprd -f

3. As user root run the below command to rebuild the initrd:

mkinitrd -k /boot/vmlinux-$(uname -r) -i /boot/initrd-$(uname -r)

4. Reboot the system

Additional Information

Possible problems:

1. In case of a second kernel failing with "Out of Memory" messages during fadump capture, use the "fadump_reserve_mem=<size>M" kernel command line to specify a larger size of the memory to reserve for boot memory dump preservation and reboot the system.

The term "boot memory" means the size of the low memory chunk that is required for the second kernel to boot successfully when booted with restricted memory during a system crash. By default, the boot memory size will not be larger than 5% of system RAM or 256MB. Alternatively, a user can also specify the boot memory size through the boot parameter "fadump_reserve_mem=" which will override the default calculated size.

2. While FADump is configured, only use the “mkdumprd -f” command to update the default initrd (instead of mkinitrd) to ensure dump capture scripts are included in the default initrd. If the default initrd is updated by other methods, dump capture scripts may not be included in the initrd. If this happens, a vmcore will not be captured automatically after a crash. Instead, the system will boot with minimal available memory and with the “/proc/vmcore” file waiting to be saved.

Disclaimer

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