Hot plug

As soon as you install Ubuntu on a POWER system, it is recommended to install the ppc64-diag package in order to enable RAS features, as for example, hot plug completation, firmware log dump, etc.

# apt-get install ppc64-diag

powerpc-utils package

In order to have the package powerpc utils installed in Ubuntu, you need to install the package named powerpc-ibm-utils instead of powerpc-utils.

The powerpc-utils is a package focused on the old POWER Apple machines and shouldn't be used in IBM POWER servers.

So, in order to install it, run:

# apt-get install powerpc-ibm-utils

Crash Kernel recommendations

The following are the recommended crashkernel values for different memory ranges. This values are arrived at after testing different scenarios:

• For memory between 2G through 4G, reserve 320M
• For memory between 4G through 32G, reserve 512M
• For memory between 32G through 64G, reserve 1024M
• For memory between 64G through 128G, reserve 2048M
• For memory above 128G, reserve 4096M

Actaully, we can pass it as a condition based crashkernel= parameter based on the size of total system memory, so that it works irrespective of system memory size, like below:

        crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M

So, the above parameter effective converts to crashkernel=320M on a system with 2G through 4G memory, while it means crashkernel=512M on a system with 4G through 32G memory and so on. Also, if Out of Memory issues are seen in kdump kernel, try increasing the memory reserved for crashkernel.

Firmware Assisted Dump

Firmware Assisted Dump (fadump) is an alternative to kdump crash dumping mechanism, available in powerpc architecture. To understand how fadump works, please refer to the kernel documentation below:

• https://www.kernel.org/doc/Documentation/powerpc/firmware-assisted-dump.txt

Two steps are needed to use fadump as the crash dumping mechanism. Firstly, enabling fadump by passing "fadump=on" to kernel. Secondly, registering fadump by echo'ing 1 to /sys/kernel/fadump_registered.

1. To enable fadump:

• Add "fadump=on" to GRUB_CMDLINE_LINUX in /etc/default/grub file.
• Rebuild grub config

        # grub-mkconfig -o /boot/grub/grub.cfg

• Reboot

2. To register fadump:

• kdump-tools, scripts and tools for automating kdump, is updated to make it fadump aware.

  When fadump is enabled, kdump-tools registers fadump as crash dumping mechanism, by echo'ing 1 to /sys/kernel/fadump_registered. For more help, see:

        # kdump-config help

NOTE: If fadump fails to collect dump with Out Of Memory error, use "fadump_reserve_mem=" parameter to spike up the memory reserved for firmware-assisted dump.