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A3312A SCSI ID numbering


A3312A SCSI ID numbering

good afternoon:

I have a K Class with an A3312A Jamaica installed. I am trying to daisy chain another A3312A. The ioscan shows SCSI ID's consecutive up to 22. How do I determine what number to put the jumper switches to for the additional drives?
ioscan shows.....
I H/W path
3 10/0.3.0
4 10/0.4.0
7 10/0.5.0
5 10/0.6.0
8 10/4/4.0.0
9 10/4/4.1.0
11 10/4/4.2.0
12 10/4/4.3.0


How much if any will end up getting renumbered?

Bharat Katkar
Honored Contributor

Re: A3312A SCSI ID numbering


1. You HBA has default SCSI id 7 so don't use that one for any device in array.
2. If you have SE devices then you can set the SCSI ID's from 0 - 6
3. If you have DF devices then you can also use SCSI ID's 8 - 15

Remeber SCSI ID has priority associated with it.

Find below the info for setting SCSI id:

1 - Bus A Upper SCSI Connector (68-pin) 9 - SCSI ID Switch B1
2 - Bus A Lower SCSI Connector (68-pin) 10 - SCSI ID Switch B2
3 - SCSI ID Switch A1 11 - SCSI ID Switch B3
4 - SCSI ID Switch A2 12 - SCSI ID Switch B4
5 - SCSI ID Switch A3 13 - P1 AC Power Connector
6 - SCSI ID Switch A4 14 - P2 AC Power Connector
7 - Bus B Upper SCSI Connector (68-pin) 15 - SCSI Bus Reset Switch (Factory Set Only)
8 - Bus B Lower SCSI Connector (68-pin)

Hope that helps.
You need to know a lot to actually know how little you know
Uwe Zessin
Honored Contributor

Re: A3312A SCSI ID numbering

Yes, but for backward compatibility the priority is: 8, 9, .. 15, 0, 1, .. 6, 7.

And SE/DF has nothing to do with narrow/wide addressing - it is the signaling on the bus.
Patrick Wallek
Honored Contributor

Re: A3312A SCSI ID numbering

The number you see in the left hand column of the output you have in your post is NOT the SCSI id. That is merely the the number of the disk as it was discovered. It has nothing to do with the SCSI ID. The SCSI ID's of your Jamaicas are the second number in the series of three numbers after the last slash in your above output. You have:

3 10/0.3.0 = SCSI ID 3
4 10/0.4.0 = SCSI ID 4
7 10/0.5.0 = SCSI ID 5
5 10/0.6.0 = SCSI ID 6
I believe these 4 drives are your internal drives.

8 10/4/4.0.0 = SCSI ID 0
9 10/4/4.1.0 = SCSI ID 1
11 10/4/4.2.0 = SCSI ID 2
12 10/4/4.3.0 = SCSI ID 3
These 4 are probably in one of the Jamaicas.

You will NOT be able to daisy chain 2 Jamaica boxes together. You do not have enough SCSI ids. As said in the other posts, you have ID's 0 thru 15, with 7 already reserved for the SCSI controller in the K box, so that leaves you with 15 available IDs. If both of your Jamaica's have 8 drives, then that is 16 total drives. That simply will not work.

The switches on the back of the Jamaica for each drive are to turn on or off the 8, 4, 2 and 1 bits (from left to right as you are looking at them from the back). For the switches you turn on (up position) you add the numbers. All four switches up means 8+4+2+1 equals SCSI ID 15. If all four are down, then it is SCSI ID 0.

It would be better if you put another SCSI card in your K box and have only 1 Jamaica with 8 drives per controller.

If these drives are going to be heavily utilized then you will also see better performance this way as well since FWD SCSI is max of 20 MB per second.

Good luck!