[rescue] O2 rescue: advice for an SGI (relative) newbie

[Jonathan C. Patschke]

On Tue, 1 Mar 2005, Michael-John Turner wrote:

> I've just acquired my first SGI system, an O2.

Congratulations!  Those are fun and capable machines, and IRIX is one of
my favorite operating systems, even if it's getting to look a bit dated.

> It has 128M RAM, a 150 Mhz R10K CPU

Oooh, an R10000 O2.  Those are relatively uncommon.  A very popular
software application for IRIX (I don't recall which--it might've been
Maya) didn't play well with the R10000 in the O2, so SGI didn't sell
very many of them.

Be aware that just because you have an R10000 CPU in there doesn't make
the O2 a fully 64-bit machine.  You can't run 64-bit binaries because
the address bus is only 32 bits wide.  You can run n32 binaries which
give you 64-bit arithmetic, though, which is where most performance
gains from 64-bit code would be, anyway.

> Today I purchased an 18G SCA drive to replace the internal
> drive and I'm going to hunt around for more RAM (I'd guess
> that 512M would be a comfortable target?)

512MB is, indeed, quite comfortable.  That 18GB disk should also be
plenty for IRIX.

> (*) How best should I slice up the 18G drive? Should I split
>    it into different slices/partitions for different filesystems?
> 	 I see the IRIX docs mention having a single slice. I prefer
> 	 having /usr, /var, etc as separate slices, or is that too
> 	 much hassle with IRIX?

It is a high-insurmountable pain in the backside on IRIX.  When you use
fx to partition and label your disk, you can chose the "usrroot"
partition layout to create separate /usr and / filesystems.  That's
generally the one I use.

On one machine I got the urge to make /var a separate slice.  It's not
fun.  For one, you have to slice up the disk by hand.  Then, you have to
migrate /usr/var to /var -after- you do the installation, because the
IRIX installer is a very simple-minded piece of software and can't deal
with the tradition Unix way of partitioning things.  It's just not well-
supported.

/usr/people is something else that's always bothered me, but I handle
that by using a second disk for home directories.

> (*) I'm planning to use NetBSD pkgsrc for management of additional
>    software. Is that a good idea? Any alternatives?

I've had mixed luck with pkgsrc.  Of course, I'm using MIPSpro instead
of GCC, so that could be the root of the problem.  I strongly dislike
GCC on IRIX; it's long had all sorts of problems with poor code
optimization and an inability to link against MIPSpro-compiled libraries
(like, say, all the ones shipped with the OS) without a strange word-
padding problem.

I understand that the alignment and padding problems have been fixed in
GCC 3.recent, but I'm not convinced the compiler optimizes that well
yet.  To be fair, I haven't side-by-side compared MIPS assembly code
generated from each compiler since GCC 2.95.3, so it's quite possible
that GCC is good stuff these days.

> (*) Is there any way to get USB working (eg with a PCI card)?

Not likely.

> (*) Is it true that I can upgrade to an R12K CPU? I've seen some
>    reference to CPU upgrades, but I'm not sure how far I can
> 	 take this baby?

I believe that is the case.  The R10000 and R12000 systems have higher
cooling demands than the R5000 and R7000 systems.  I think that, across
all four processor familes, the system board is the same.  The R10000
and R12000 systems omit one of the disk slots and replace it with dead
space to accomodate the R1[02]000's larger heatsink, so you can't upgrade
from an R5000 to R10000 without nasty surgery.

-- 
Jonathan Patschke   )   "Trying is the first step towards failure." 
Elgin, TX          (                                   --Ben
USA                 )                                    (in #posix)