[SunRescue] Booting a Sun3

[James W. Birdsall]

>>    1) Sun-3's will not boot from a disk that has SCSI parity turned on.
>
>Mine certainly do!  (3/260's with not too ancient ROMs and an "si" host
>adapter)  I'd have thrown them back out if they didn't!  SCSI parity is
>critical and I though only stupid PCs and some MACs didn't support it
>properly....

   OK, I'll admit that I've never actually tried it. When I was buying my
first Sun in 1991, this factoid was passed on to me by the elders at the
Sun software shop where I worked at the time, that Sun-3's would not boot
from disks with SCSI parity turned on but would mount them afterward. It's
probably a ROM revision level thing.
   In November, I'm going to be reorganizing all my machines as part of the
rollover to NetBSD for Y2K compliance and security reasons. If I remember,
I'll test SCSI parity with the wide variety of Sun-3's and ROM levels that
I have, and report on my findings. (I have a lot of older ROMs; I
personally like them better because I'd rather have extensive diagnostics
than support for boot devices that I don't have.) It's not that I don't
want to run SCSI parity, I just previously didn't see any point in wasting
my time trying something I'd already been told wouldn't work. :)

>>    2) Sun-3's don't have the 3/0 SCSI ID inversion that SPARCs do. When you
>> tell a Sun-3 to boot from the disk with SCSI ID 0, it really does, instead of
>> remapping it to SCSI ID 3.
>
>Again, I'm sure my 3/260's do have the sd0 == SCSI#3 translation!

   Only if you have created a custom kernel which does so. At the ROM level
there's no translation mechanism. In fact, the sun4 family may not have it
either. I know that sun4c's do; the rationale was so that users could
connect old shoeboxes to new SPARCstations with internal drives without
having to open anything up and change SCSI IDs. I'm sure somebody somewhere
got into trouble anyway with a shoebox that used ID 3, but they were few
and far between. At three shoeboxes on a chain you're pushing the SCSI
length limits and only up to ID 2 on the hard drives.

   --James