SCSI Hub (DWZZH) Configuration

[Michael Hackelton]

Hi.

I'm having some issues converting my 2 node OpenVMS cluster from a "Y" cable connection to a SCSI hub. My intent is to add 2 more nodes into my cluster, so I bought and installed a DWZZH-05 SCSI hub. Here's my configuration:

host 1:
KZPBA (SCSI ID 2) connects directly to the DWZZH using the upper right port.

host 2:
KZPBA (SCSI ID 0) connects directly to the DWZZH using the lower right port.

HSZ70 pair connects to the upper left port of the DWZZH.

I've also installed the jumper on the back of the DWZZH to use narrow SCSI addressing.

My question is related to the SCSI ID's of the hub and HSZ70 controllers.

At the HSZ70 prompt, a "SHOW THIS" and "SHOW OTHER" indicate the SCSI ID's to be 6 & 7. According to the DWZZH documentation, the ID of the hub is also 7 and is not configurable. My thinking is I have a SCSI ID conflict. The HP help desk says that's not true, theat the controller ID's are changed at the hub, which doesn't make sense to me. Is there a way to change the SCSI ID's of the HSZ70's?

If not, what am I missing? I cannot see my disks from either of the 2 hosts.


Oh and on the KZPBA in host 1, I reinstalled the internal SCSI terminators (8 mustard colored jumpers) per one of the HP documents I found on the DWZZH. These are the jumpers I had to pull to make the configuration work in the "Y" cable scenario.

I've also tried disconnecting host 2 (haven't found its jumpers yet).

Any ideas? Thanks

-Mike

[Uwe Zessin]

The HP help desk is right (that 6&7 do not represent a conflict), but the explanation is wrong :-)

> At the HSZ70 prompt, a "SHOW THIS" and "SHOW OTHER"
> indicate the SCSI ID's to be 6 & 7.

What you see is the addresses the controllers use at the back-end (where they talk to the disk drives).

The front-end addresses are defined by the "unit IDs": e.g. D300 is SCSI ID:3, LUN address 0; D402 is SCSI ID:4, LUN address 2.

On such a configuration, you give the highest SCSI IDs (7, 6, 5, ...) to the servers' SCSI adapters (e.g. KZPBA) and the lowest IDs to the units on the HSZ (D0..D7, D100..D107, ...).

[Michael Hackelton]

>> At the HSZ70 prompt, a "SHOW THIS" and "SHOW OTHER"
>> indicate the SCSI ID's to be 6 & 7.

>What you see is the addresses the controllers use at the back-end (where they talk to the disk drives).

But at the back-end then, my controllers are 6 & 7. Doesn't the hub which they are connected to also reside on that same bus? Then the hub's address of 7 would conflict with the controller's address of 7.


>The front-end addresses are defined by the "unit IDs": e.g. D300 is SCSI ID:3, LUN address 0; D402 is SCSI ID:4, LUN address 2.

>On such a configuration, you give the highest SCSI IDs (7, 6, 5, ...) to the servers' SCSI adapters (e.g. KZPBA) and the lowest IDs to the units on the HSZ (D0..D7, D100..D107, ...).


The drives are already configured at the HSZ70 level. That would be the front end according to your explanation. My unit ID's are:

D1 - D6
D101 - D106
D201 - D206
D301 - D306
D801 - D806
D901 - D906
D1001 - D1006
D1101 - D1106

If the hub resides on the front-end, and the 1st number behind the "D" has something to do with the SCSI ID on that front-end bus, then I'm really confused.

Thanks for the help!! I realize you have to go way back to deal with these ancient DEC issues. :-)

-Hack

[Uwe Zessin · Accepted solution]

A HSZ70 controller module has 7 (seven!) SCSI busses:

- Six (6) back-end busses which are used to talk to the disk drives. Depending on the controller position (A/B) it uses either SCSI ID 7 or 6 on all of these six busses.

- The seventh (7th) bus is the front-end bus to which the hosts are connected. The controller does not tie up a SCSI ID for itself here. It just presents the units (D7, D402) which the hosts recognize and 'beleive they are real disks'.

The 'D' in the unit name just means "Disk" - it has nothing to do with the SCSI ID/LUN address.

[R. Verkerk]

Hello,

Yust wondering: Why go to narrow addressing?

Is the HSZ70 is connected to the device port of the DWZZH?

If you have the dwzzh-05 like this:

---1
---2 ---4
---3 ---5

Than slot one (1) is where the HSZ70 should be connected and the other slots are for systems only.

greetings,

Robert Verkerk.

[Uwe Zessin]

Narrow addressing? D801, for example, is in the wide range.

Initiators use SCSI IDs 7,6,5,... because they have the highest bus priority.