Changing Boot Settings

Adding Steps to the node_up Script

If you wish to add more steps to be executed during the node_up script, you can do it without actually editing the script. Instead, you create a script in the /etc/beowulf/init.d/ directory. All scripts in this directory will be executed for each node that boots up. This script will be sourced by the node_up script when the specified node boots, therefore it must be written in standard sh. When your script is sourced, the variable $NODE will be set to the node number that is booting. See the Section called Site-Local Startup Scripts in the Appendix called Special Directories, Configuration Files, and Scripts for more details.

Per-Node Parameters

Starting with Scyld Series 30, support is provided for specifying kernel image and kernel command line parameters on a per-node basis in the cluster config file /etc/beowulf/config. This enables one set of nodes to boot with a particular initrd image, while another group boots with a different one.

The utility of this feature can be illustrated by the use of the memtest86 memory testing utility. For example, if you had just expanded your cluster with 5 new nodes (nodes 16 through 20), and you wanted to test their memory before putting them into production, you could have them all boot into memtest86 rather than the usual Scyld initrd with the following entry in /etc/beowulf/config:

kernelimage 16-20 /var/beowulf/boot/memtest86.bin
initrdimage 16-20 none
kernelcommandline 16-20 none

Other Per-Node Config Options

The cluster config file /etc/beowulf/config provides per-node support for node state changes, which allows the use of other scripts or tools to control and manipulate the wake, alert, and down states of nodes in the cluster.