5.4 Sockets

		3. Set up a clone root directory on the worldly node.

		4. Configure bootp on the worldly node.

		5. Install a special init script in the clone root directory on the worldly node.

		6. Create a boot disk with an NFSROOT kernel.

		The basic premise behind the cloning procedure is for the new node to mount a root file system over NFS, which contains the cloning support programs, configuration files, and partition archives. When the Linux kernel finishes loading, it looks for a program called /sbin/init, which executes system initialization scripts and puts the system into multiuser mode. The cloning procedure replaces the standard /sbin/init with a program that partitions the hard drives, untars partition archives, and executes any custom cloning configuration scripts before rebooting the newly cloned system.

		6.3.1 Creating Tar Images

		To get ready for cloning you have to configure an initial internal node. How you configure it will depend on how you intend to use your Beowulf. But you will more than likely install the basic operating system and network clients like the NFS automounter. Whether or not you install a full set of compilers and message passing libraries is up to you, but in general, development tools are not duplicated across internal nodes and normally reside on the worldly node.

		After configuring the internal node, you need to make an archive of each disk partition, omitting /proc, which is not a physical disk partition. Some cloning software may provide a front-end that asks you some questions and automatically archives each partition for you. But most of the time you will have to take care of it yourself. The normal procedure is to change your current working directory to the partition mount point and using the tar command like:

		tar zlcf /worldly/nfsroot/partition-name.tgz

		The l option tells the tar command to only archive files in directories stored on the local partition, avoiding files in directories that serve as mount points for other partitions. A potential pitfall of this archiving method is that you may not have enough room on the local disk to store the partitions. Rather than create them locally, you should store the tar file on an NFS partition on the worldly node. Ultimately, you will have to transfer the files to the worldly node, so you might as well do it all in one step.