A3312A and cables

[Fred Martin_1]

I am setting up a A3312A enclosure. I have read the installation manual, but still have a question.

I am only installing 2 disks right now. The manual suggests loading from the bottom up, and left to right. There are 2 bays with 4 slots each. The slots are numbered like this:

A4 B4
A3 B3
A2 B2
A1 B1

So I have disks in A1 and A2.

The manual's cabling suggestions show that I can cable the two bays seperately to two different adapters, or with a short cable string them together so all 8 bays are on one adapter.

Question 1: If I'm only using the A bay, can I cable the top A connector to the adapter, then terminate the lower A connector? This would leave both B connectors open for future use. Or, should I connect the A and B bays together as though I were loading up both bays to one adapter, as shown in the manual?

Question 2: Should I assign ID's the unused slots anyway, as though there were disks there? There's a warning in the manual about not setting addresses to 0, but nothing about how to address open slots.

[Sajid_1 · Accepted solution]

hello,
a) If you are only using A bay, connect the adapter to A bay and terminate at the lower level. That will work properly. You don't need to connect B bay with same adapter, you can connect another controller here in future.
b) There is no harm in assigning SCSI IDs now to all slots. You can address now, or later depend up on your wish. The only important thing is never assign same IDs to different slots that comes in the same SCSI bus

[Fred Martin_1]

Hello again Sajid,

Do you mean that unused slots will be ignored by the controller?

For example, my disks are in A1 and A2. On this bus, all the addresses are presently open (except 7).

So:

A4 (5)
A3 (5)
A2 (9)
A1 (8)

The two top slots have no disks in them, and for this example I've addressed them both as 5, which is an unused address at present.

I don't like playing with fire so I'll most likely pre-address all slots, used or not, to unique numbers.

For the sake of argument I ask the question anyway. I can see a situation in the future where I might have a bus with only a few open addresses and more slots than I could possibly address - then I'd need to know.

Thanks.

[Sajid_1]

Hi again,

In your adapter, you could only connect up to 15 devices. So in future, even if you have more slots to address, you could *only* use the unused SCSI IDs and the rest of the slots should be connected to a different controller.

What I would suggest is to address all slots before you start. Address it in order so that you won't have any confusions in future. To answer your question, I think the adapter will not give any issues evenif you set the same SCSI IDs in the *empty* slots. I never tried it though. Normally a SCSI ID clash comes when two devices coming with the same ID. Here there is no device

[A. Clay Stephenson]

There is no problem at all with duplicate SCSI ID settings as long as no more than one of the duplicate slots is actually occupied. If you go ahead and preset the DIP switches there is less chance that you will accidently have more than one occupied slots with a common SCSI ID.

[Fred Martin_1]

Yes I agree with the safest route. Since this enclosure is the only thing on the bus at present, all addresses are open except 7. I'll address all 8 slots, using 9 through 15.

I'm running the cable from the adapter to the top A connector, terminating the bottom A connector. For the time being both B connectors (and slots) will be left open.

Many thanks,
Fred

[Sajid_1]

Just an addition - If you want to get the highest SCSI ID priority, then assign 6-0 IDs to these disks. The SCSI IDs from 8-15 are lowest priority. This doesn't matter now as you have only 2 disks, but will matter if disk performance is an issue in future.

gl,