Re: SCSI ID vs. unit ID

Hello Holger,

Am 17.01.2022 um 20:04 schrieb Holger Scherer <hs@xxxxxxx>:

The external connector on the back of the 150 can drive an additional tape drive with active LVD terminator, if you are lucky.

Mh, that's what I thought, if I'm lucky. ;-)

Some combinations work, some dont. You might want to test a DDS3 drive with Adapter to 50pin SCSI, as well as some old LTO1 drives ;-)

LTO is *much* to fast for the poor 150. It will make the drive scream with stop-start. :-) When using two 15kRPM drives, or four 7200RPM drives, a DDS3 is just fine. Otherwise, I recommend a DDS2, to avoid the non-streaming mode.

These are my findings so far:

https://try-as400.pocnet.net/wiki/Tape_Drives_on_old_AS/400

If anybody has tried other combinations not officially blessed by IBM, I'd be glad to know and document them.

For external disk, the Bus might not work well, you might try 6 disks by using SCSI ID 6, 5, 4, 3 and 8, 9 (no guarantee).

I'm not sure if the SCSI IDs play a role. And, the bus is the same. I can only guess that the triple termination as described might do something undesirable?

There is no direct mapping between SCSI ID and Unit ID, as this is defined per model (or: per system case for 150, 170, 600, etc)

A-ha! Okay, this explains why there seems to be no simple mathematical way to calculate these. :-)

170 is much more fun to play with, as Larry pointed out :)

Maybe? I don't have one, and I'm pretty sure, it uses (much?) more than the roughly 67W my 150 (two 15k disks + IPCS, platinum certified ATX PSU) uses. :-)

It also has an external connector to be used with the internal bus, but as 170 does support RAID cards with multiple SCSI buses, you can connect external SCSI devices by simple adapter cables.

Sounds good!

:wq! PoC