Building a Node system

Preparation for building a new nodes means collecting a Pentium (or better) CPU some RAM, two or three wireless lan cards and an Ethernet card. A 500 Mb harddisk (or more) will do fine. The BIOS of the PC is configured to boot from floppy disk, or in the case of the Soekris, to boot from the network using PXE. Besides the BIOS on the Soekris machines, we have not tried any BIOS-es or Ethernet cards which supported PXE directly but have relied on a few different etherboot floppies instead.

In the first stage the new machine boots from floppy disk to initiate etherboot. DHCP will assign an IP address and provide the parameters which allow the node to mount the NFS file system. After loading the kernel, a script prepares the harddisk by making it bootable, defines its partitions and formats file systems. This is followed by copying all the files from the server to its own harddisk. After a reboot the new machine has it own system in order to run.

After the reboot installation of some packages such as a dhcp-server, a nameserver, snmp etc. takes place. The installation is managed by a set of homebuilt scripts (see section 7). The reason to do so after a reboot rather than during the diskless boot is that during the initial diskless boot we do not want to rely on having sufficient memory available. The diskless system uses a memory based /var and /tmp overlay and therefore consumes quite some memory. The scripts are invoked by a state engine at the end of the boot procedure.

At the end of the procedure the new machine will show a list of hostnames. After entering one at the command line the machine will lookup its configuration on the Internet in the remote Genesis. The old files will be backed up and the new ones that define the specific node will be put in the right places.

Then approximately 15 minutes after the first (floppy) boot, the new machine is in operational state and ready to be deployed and located at site.