[rescue] More IRIX questions: why won't it boot from my 6.5.24 CDs?

Sheldon T. Hall shel at tandem.artell.net
Sat Apr 7 18:18:04 CDT 2007

Micah R Ledbetter writes ...
> On Apr 7, 2007, at 17:31, Sheldon T. Hall wrote:
> > Is the CD-ROM drive jumpered to use 512-byte sectors, rather than  
> > the usual
> > 2048?  This jumper is often called "block" on the drive case.
> Ah hah. Changing CDROM drives to 512-byte sectors fixes this. (I  
> don't think that my first drive had such a jumper... I couldn't find  
> one, anyway)

SGI machines are rather picky about CD-ROM drives, as suggested by the
amount of net-foo-foo you can Google up.  They are much more picky about
boot drives (and bootable CD-ROM disks) than they are about day-to-day disk
reading, but they are semi-picky there, as well.  

However, the more recent SGI machines (say mid-1990s onward) aren't nearly
as bad as the earlier ones were, and, of course, CD-ROM drives have
improved, too.  Still, it ain't like PCs, where any IDE CD drive will Just

A drive that SGI shipped with the machine will work, of course, and, as a
bonus, it's very likely to do audio-over-SCSI.  However, rescuable SGI boxes
mostly shipped with 2x caddy drives, and that makes the usual 15-CD IRIX
install-to-current-plus-freeware session rather tedious.

I have attached various CD and DVD drives to my SGIs (Indy, Indigo2, Octane,
Challenge L).  Most of them boot from an appropriate CD disk if jumpered to
512 byte sectors.  This includes some drives as fast as "32x", which makes
installing IRIX a lot faster than on the normal 2x drives shipped with, say,
the Challenge.  Even one of the DVD drives I have will boot my Octande.
Neither of the DVD drives is that good about reading actual DVDs on the
Octane, though.  I've read that this is a problem with the mediad program,
as is a reported difficulty with reading CD-RW disks in some drives.

To add to the SGI Compact Disk Mystique, the dam' machines will only boot
from EFS-formatted boot CDs, and making those on anything but an SGI is a
Black Art.  

Given that SGI didn't care to fix this when MIPS/IRIX was alive, it's
probably a situation we'll have to live with.

Once, for amusement value, I hooked up a Nakamichi 6-disk changer to my
Indigo 2.  The OS saw it as 7 drives, but that was the extent of its
usefulness.  Rather than actually read any disks I put in it, the OS (or
mediad, I don't know) just endlessly shuffled from one disk to the next
until I turned off the drive.  I was really sorry it didn't work better, as
I had visions of the changer being, essentially, a sort of portable, plug-in
install server.

Once you get IRIX 6.5.whatever installed, be sure to apply the inst patch
before you try in install the update to 6.5.22 from SGI's website.


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