SGI: Hardware

Howdy once again.

My "Challenge XL" came to me with a few disk trays for the drive trays that came with my "franken-rack."

Once the weather gets cooler I want to install/play with this thing, so I'm lining up drives to go into it. I'm looking for documentation on the trays; essentially what do the jumpers do, and why do we have two 50 pin connectors in them, which one I should use, how I should handle termination, etc.

Per everyone's advice I have the LVD cable disconnected and am only going to run one tray at SE. I don't think the

I have a few different trays, too. They all have the same back, but one is missing the front and doesn't have the SCSI-ID change-o-matic number selector. I'm assuming I can throw a CD-ROM in that for local booting. I'm going to have to dig out a 50-pin to 68 pin adapter for my other drives (or 50 to 58 to 80, as I have a lot of SCA stuff.)

Any advice or guides you can throw my way?

Thanks!

SGI documentation here: http://techpubs.sgi.com/library/tpl/cgi ... /ch04.html

Basically, the drive cage (and its disk sleds!) is wired to two SCSI channels. Each sled has thus two SCSI connectors, JA and JB, and depending on which connector you plug your device into, it shows up on the first or second SCSI channel.

Each SCSI channel in turn, can be configured for SE or HVD operation. This is done with the green or red daughter cards on the IO4, the terminators and jumpers on the drive cage backplane. The jumpers on the sleds must match this configuration. As a result the same jumper configuration must be set on all sleds .

The sleds themselves exist in two flavors: narrow and wide. Here's two from my Onyx IR :

To the left a HVD hard disk, configured as scsi(1,1). To the right an SE SCSI CDROM, configured as scsi(0,6)

So: SCSI0 is SE, SCSI1 is HVD. This is the default configuration and yours is likely configured like that as well.

Here's a closeup of the sled holding the hard disk:


Notice how the (wide) SCSI cable is connected to JB, the 2nd SCSI channel.

The configuration is done with the jumper block between the connectors. Actually, it's two jumper blocks, H1 (left, fully populated with 4 jumpers) and H2 (right, half populated with two jumpers).

IIRC, H1 sets SCSI channel A, and H2 sets SCSI channel B. Fully populated (H1, left, SCSI0) means SE. Half populated (H2, right, SCSI1) means HVD.

This particular disk sled has an original, HVD disk installed. If I wanted to install a more modern SE or LVD disk, easiest would be to simply move the 68pin flat cable to JA and leave the SCSI setup unchanged. The disk would show up on SCSI0, but that doesn't matter.

Originally, the SCSI device ID of the disk is set using a selector on the front of the disk. This connects to the jumper block on the actual disk. Unfortunately, these jumper blocks are absolutely not standardized, so you probably want to ignore it and simply set the relevant jumpers on the disk.

If you want to change an entire SCSI channel from SE to HVD or vice versa you must change IO4 daughter card(s), terminator(s), and all relevant jumpers at the same time or risk the release of magic smoke left and right. HVD and SE SCSI don't mix well! I documented some of this work here: http://www.vdheijden-messerli.net/sgist ... challenge/

Edit: moved advanced stuff to the end

This is exactly what I was looking for. The different drive sleds I have all had different jumper configurations. I've reset them to SE-A, HVD-B (even though HVD is disconnected at the IO4 card.)

The goal is to maybe get an OS installed tonight depending upon weather. I have IRIX 6.5.3 (Foundation & Overlays) ready to go. It got my O2 working, so now it's time on this, while it gets cooler outside.