SCSI 'network': Where did I go wrong?

[jus]

Hi,

Yesterday I've been trying to set up a scsi network between my amiga 4000 and a draco so I can use the CDR and Scanner on both machines and easily exchange files between the both (the 4000 has alot of harddisk space and software, where the hd on the draco is completely used for storing anims and sound) But it wasn't as easy as I thought it would be.

Here is what I've done:

Intern A4000:
       68 Pins Terminator
--------------------|
       ID 0 - HD Seagate 68 pins
--------------------|
       ID 2 - Controller CSPPC UW
External---------|---------68 to 50 Pin Cable
       ID 1 - Epson Scanner
--------------------|
       ID 5 - Plextor CD-Writer
Intern Draco---|---------50 to 25 Pin Cable
       ID 7 - SCSI-2 host Draco
--------------------|
       ID 3 - Quantum HD 50 pins
--------------------|
       ID 4 - Quantum HD 50 pins
--------------------|
       ID 6 - CD-Rom Toshiba (terminated)

Termination power is provided by the seagate HD and the Draco SCSI, Which doesn't seem to be a problem because the lenght of the cables between the two is rather enormous (two to thee metres maybe).

When one machine is off the other can easily access the scanner and the CDR (either the a4000 or Draco) But when the other machine is turned on it of course resets the complete bus. The machine doesn't boot and it makes all the other drives inaccessible to the other machine. When it does boot, the other machine can't acces any of the drives. When I switch them both on at the same time, none of the machines boot, the bus gets reset a few times, the a4000 turns to the 'please insert disk' screen, the draco stays in the bootrom screen.

What did I do wrong? Is what I'm trying to do possible at all?
Any hints anyone?

Thanks
Justin

[tonyw]

Sadly, it's not possible. Although the SCSI standard allows for two or more controllers on the same bus, in practice, most, if not all controllers don't "let go" of the bus when they're not using it. So another controller can't get control of the bus to use it.

There may be a controller somewhere that does the right thing and lets it go, but I've yet to meet it.

tony

[whabang]

It should be possible, but I don't know if this particular config'll work.
AFAIK, you have to put the computers at each end of the SCSI chain, though.

[pjhutch]

For it to work you have to change the SCSI id of one of the controllers to another id other than 7 otherwise it will never work. Not all SCSI controllers can change its own scsi id and then not all controllers will work on the same chain.

Get a couple of Ethernet cards and set up an Ethernet network instead - mucher simpler and should do some of the things you want to do.

[jus]

Well I didn't know that both controller's IDs should be different from 7, I thought they only had to be different (which they are in my setup).
The SCSI controllers in the draco and the CSPPC are both Symbios logic so I thought they might do the trick.
Of course I considered getting an ethernet card for the draco (the 4000 is already on a network with a PC) But i'm not sure if the XSurf would be compatible to the draco zorro slot. I would also have to buy an ethernet hub, which is quite an expense compared to a scsi cable.
Also, It wouldn't really allow me direct access to for example the scanner and the CDRW on the computer to which they are not connected. I also wouldn't be able to access te JPEGs that Movieshop writes to the HD on the a4000 to process them with let's say Wildfire (which is PPC).
Anyway, maybe I'll have to find some other solution...

Thanks anyway!



Justin

[tonyw]

You don't have to have a hub. You can use a reversing cable between two computers (the Ethernet version of a null modem cable). Pretty cheap at most shops.

tony

[seer]

Browse through these forums, maybe they will offer some help.