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A two-step procedure was used to generate remote bootstrap floppy disks for client machines. First, the kernel source residing on the server was recompiled to include “root file system on NFS (Network File System)” support. Once compilation was complete, the newly created kernel image was moved from /usr/src/linux/arch/i386/boot/zImage to /tftpboot/adm/client_boot_image_remote. A new disk was labeled and inserted in the server's floppy drive. A dummy device, /dev/boot22, was created with the mknod utility. The dd utility was used to copy client_boot_image_remote to the floppy disk. The rdev utility was then used to set the root device for the kernel residing on the floppy image to the dummy device /dev/boot22. The following sequence of commands was used to create the remote bootstrap floppy disk:
mknod /dev/boot255 c 0 255 dd if=/adm/client_boot_image_remote/zImage of=/dev/fd0 rdev /dev/fd0 /dev/boot255
Finally, this procedure was captured in a shell script and used to create additional remote bootstrap floppy disks.
All client systems included a hard disk configured to provide a single 50MB swap partition, /dev/sda1. This would allow experimental users to partition the remainder of the drive to suit their needs when installing Linux on their systems. Because the only CD-ROM resides on lin2, any installation of Linux to a client system other than lin2 has to be done via NFS. To make such an installation possible, modifications to the MCA Slackware 3.1 boot floppy were necessary. The boot floppy was mounted under the /mnt directory using the command
mount -t minix /dev/fd0 /mnt
The file /mnt/etc/networks was updated, changing LOCALNET to IP address 220.127.116.11. The MCA Slackware 3.1 boot floppy assumes that if a network installation is being conducted, the network is of type Ethernet. Therefore, it was necessary to edit the file /mnt/usr/lib/set/INSNFS, changing all occurrences of eth0 to tr0. As with the remote bootstrap floppy, a script was written to automate the above operations.
The declining cost of disk drives, together with concerns about system security, have made diskless workstation operation and remote protocols like RARP less attractive. “Relatively inexpensive”, however, is still not quite “free”. We described a strategy for implementing a Linux-based laboratory that, in effect, uses diskless operation to support regular as well as standard users, at no additional cost.
ETSU's Linux-based computer lab has not been fully integrated into the ETSU curriculum, due primarily to unforeseen delays including equipment outages caused by a thunderstorm. The lab, however, is operational. Two students used the lab in spring 1998 to develop a serial line driver for a senior-level operating systems course. Currently, plans are being made to use the laboratory as a tool for teaching graduate operating systems and undergraduate networking courses in the coming academic year.
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