HP Insight Cluster Management Utility v7.2 User Guide

5.8.2.9 Understanding the structure of a diskless image
Like every HP Insight CMU image, all directories and files related to an HP Insight CMU diskless
image are stored in /opt/cmu/image/<imageName>.
A diskless image is composed of the following directories:
• root—Contains the root directory of the golden node and is mounted in read-only mode by
the diskless compute nodes and used as '/'.
• snapshot—Contains one subdirectory per node. Each subdirectory is created when you
register a node or a set of nodes into the diskless logical group and contains the files mounted
in read/write mode for each compute node. Snapshot directories are populated as defined
in the following files:
◦ files—The list of files to be put in the per node snapshot directories. This list is
provided by the diskless feature of HP Insight CMU. Do not modify this.
◦ files.custom—Add to this file the list of custom files that you want to put in the per
node snapshot directory.
When starting a node with a diskless image, HP Insight CMU modifies the dhcptab to network
boot the nodes on the diskless image.
5.8.2.10 Customizing your diskless image
5.8.2.10.1 files.custom
As described in “Understanding the structure of a diskless image” (page 74), add to files.custom
the list of custom files you want to put in the per node snapshot directories.
5.8.2.10.2 Using reconf-diskless-image.sh
The reconf-diskless-image.sh script is executed at the end of the image building process.
This script contains any modifications to be applied in the read-only part of the image mounted
by the nodes.
To this script, add all the commands that you want to execute before the creation of the snapshot
directories, such as the personalized read/write directory for each compute node. For example,
you can customize the list of files to be copied into the snapshot directory.
The reconf-diskless-image.sh content provided by HP Insight CMU is:
#!/bin/bash
#cmu_begin_interface
#do not change anything in this section
#add custom code after this section
CMU_RECONF_DISKLESS_IMAGE_VERSION=1
# starting with cmu version 4.2
# this script is now dedicated to custom code
# this code is executed as the last step of the creation of
# a diskless image
#
# this script is invoked by /opt/cmu/tools/cmu_dl_post_image
#
# environment variables available:
#
# CMU_RCFG_PATH = path where the root filesystem is currently mounted
# CMU_RCFG_HOSTNAME = hostname of the compute node
# CMU_RCFG_DOMAIN = dns domainname of the compute node
# CMU_RCFG_IP = mgt network ip of this compute node
# CMU_RCFG_NTMSK = net mask
74 Provisioning a cluster with HP Insight CMU