Boot from SCSI

[Cassandra Stinson]

I want to boot Linux from my external SCSI, rather than my internal IDE. I have an XW5000 HP. I installed linux on the external drive, with MBR on external, and internal IDE stayed free. I have checked all of the Bios settings and changed the boot order of the SCSI to be the SCSI drive first, but no luck booting to the linux external drive. Still tries to access internal IDE (which has no OS). Any suggestions?

[Goran Koruga]

Hi.

Did you also check SCSI BIOS settings ?

G.

[Cassandra Stinson]

Yes. The SCSI drive is listed, but there is no way to prompt for it to boot from SCSI. Now if I have the internal IDE drive in and disable it under the boot device under F2 menu. Then it will boot from SCSI. Without the internal drive attached at all, it will not boot from SCSI.

[Stuart Browne]

Welcome to the wonderful world of IDE vs SCSI.

By default, most BIOS' will boot roughly in this interface order:

Floppy
IDE
SCSI

Now, most modern BIOS' can be told what the boot order will be (CD-ROM, Floppy, HDD, Network), but not all of them know that a SCSI interface is bootable.

So simply put, unless you can tell your BIOS to look at a SCSI device before an IDE device, you have to do things a little differently.

How so?

Simple.

Instead of (just) using the MBR on the SCSI device, you need to write the boot loader (either Grub or Lilo) to the MBR of the IDE device, as this will probably be the first thing that gets seen.

Once it is written there, you can happily configure it to boot off different physical devices, just by pointing the boot objects to different areas (using 'root=' etc. etc.).

Hope this helps a bit. If you want more details on what needs to say what, tell us what boot loader you are using, and what it's current configuration file says (i.e. /etc/grub.conf or /etc/lilo.conf).

[Dave Unverhau_1]

Cassandra,

If you have the SCSI drive powered off (just the IDE drive enabled), what happens? I ask because I once tried to install RH 5.1 onto a PC with such a config and it behaved similarly. What appeared to have happened was that RH didn't recognize that the IDE drive was disabled in the PC BIOS and it installed LILO onto the IDE anyway. It was like Deja Vu, because I remember the same thing happening with IBM OS/2 a few years ago...

If it does appear that LILO actually went onto the IDE drive, you probably just need to boot Linux with the IDE drive "disabled", then write LILO onto the correct drive.

Regards,

Dave

[Goran Koruga]

Or as I like to put it : welcome to the wonderful world of HP BIOS-es ;).

G.