6. Booting from a Jaz Cartridge

6.1 BIOS Issues

If the Jaz drive co-exists with other SCSI harddrives, most BIOSes will want to boot the disk that has the lowest SCSI Id. The Jaz drive can be set to SCSI Ids 0-6, and typically come out of the box set to SCSI Id 5. Some BIOSes detect and skip removable devices like the Jaz. If your BIOS will boot from a Jaz, you can set your main SCSI harddrive to SCSI Id 1, then you can change the Jaz from SCSI Id 5 to 0 when you want to boot from the Jaz.

More typically, the Jaz drive co-exists with an IDE harddrive. Nearly every BIOS will want to boot the first IDE harddrive. Some BIOSes will allow you change a setting in the BIOS setup to boot from a SCSI device first. Others may require you to disable the IDE drives in the BIOS setup. Still others may require detaching the IDE drives physically or disabling the IDE interface.

6.2 Installing Linux on a Jaz Cartridge

Although running Linux from a Jaz cartridge is much slower than running from a harddrive, the Jaz drive makes an excellent ERD (Emergency Repair Disk). It's also fun to be able to just pop in some new Linux system or to try Linux on someone else's Jaz-equipped machine.

By far the easiest way to install Linux on the Jaz cartridge is simply to follow the install procedure for your favorite distribution with the Jaz drive being the only drive on the system. I've done this with RedHat 5.2, and it works perfectly. If you're not completely comfortable with doing weird, wild stuff with LILO, it's the only way to go.

If you want to do an "install" from your running system, you can often succeed in "building" a bootable system on a Jaz cartridge.

• Partition the drive and make the filesystems. You probably need to have a swap partition, too, but if you have lots of RAM then maybe not. Mount the new root as /jaz and any additional partitions within that directory as appropriate.
• Copy all the files into place. Be sure all the /dev files are copied. Be sure all permissions, ownership and group ids are retained.
• Modify the files on the Jaz cartridge to suit the circumstances of booting from it. In particular be sure to change /jaz/etc/fstab to mount the Jaz cartridge partition(s) as appropriate. Also change /jaz/etc/lilo.conf to match as well.
• There are two alternatives for installing the LILO boot loader:
  • Make a kernel image floppy and use rdev to make it mount the Jaz cartridge as root. Boot from the floppy when ready the first time then run LILO to make the Jaz MBR bootable.
  • You can run LILO from your non-Jaz root running system to install the bootable MBR on the Jaz cartridge. For more information on this option, check out Alessandro Rubini's LILO mini-HOWTO