Preparing the master image

Before any nodes can be booted, a `master image' must be created that will be shared across all nodes of the cluster. A filesystem image, normally an installation of some Linux distribution, must be copied into an NFS-exportable directory to serve as the image of the cluster.

Creating the master image from an installed linux machine is a simple process, although it can take some time to copy such a large volume of data. The copy-rootfs script (section 6.3) automates the details of copying a root filesystem from the local machine, or from a remote machine with an ssh daemon running.

After it has been prepared, this master image will serve as the root filesystem for all cluster nodes. Copies are used on diskful nodes, and the image itself is NFS mounted read-only on diskless nodes.

Procedure 2   Create a root image

 $\bullet$ Method 1: Creating an image from the local machine

This will copy the root filesystem of the local machine into /var/lib/oneSIS/image
# copy-rootfs -l /var/lib/oneSIS/image

 $\bullet$ Method 2: Creating an image from a remote machine

For a remote machine named rook, this will copy the root filesystem of the remote machine into /var/lib/oneSIS/image, excluding the remote /home directory.
# copy-rootfs -r rook -e /home /var/lib/oneSIS/image

Note: If it wasn't installed on the remote machine, oneSIS will need to be installed in the image. In the oneSIS source directory, run
# cd oneSIS-2.0.5
# prefix=/var/lib/oneSIS/image make install

Also note: If the local machine and the image use different versions of Perl, it may be necessary to chroot into the image before installing oneSIS. This will ensure that the oneSIS perl module is installed under the right directory in /usr/lib/perl.
# cp -a oneSIS-2.0.5 /var/lib/oneSIS/image/usr/local/src
# chroot /var/lib/oneSIS/image
# cd /usr/local/src/oneSIS-2.0.5
# make install
# exit

Although diskful machines can mount their local root filesystems in read-write mode, it is often desirable to treat the nodes as if they were diskless and mount the root filesystem read-only. This is especially important if the diskful nodes are intended to distribute the image to more diskless nodes. Any necessary filesystem alterations can be made in the master image, and synchronizing diskful nodes with the master image is accomplished easily with the sync-node script (section 6.6).