Re: mobile rack termination question

Thomas Maier-Komor wrote in news:fcbfd6$p39$1@xxxxxxxxxxxxxxxxxx
daytripper schrieb:
On Thu, 13 Sep 2007 15:25:19 +0200, Thomas Maier-Komor <thomas@xxxxxxxxxxxxxx> wrote:

Hi everybody,

I have a set of two U320 SCA-2 disks that I had attached with an
external SCSI box which was unfortunately SE only. So I would like to
attach both disks to an internal SCSI bus, which is U320 capable. For
this I installed a new LSI-Logic 32320 controller, attached an LVD
cable, and added two hot-swap mobile racks which have SCA-2 to HD68
adapters build in (Jou Jye 131-C see www.jj-computer.com/mobile_sca.htm).

To start I installed just one mobile rack and attached the LVD cable one
end at the HBA, the other at the mobile rack.

Is this setup sufficient for automatic termination?

What automatic termination. Do these racks autoterminate?
Do they have in and out connectors?


I saw the following behavior: the disk is detected during boot, the OS
accesses the disk and pretty fast detects an incompleted operation.

At that moment the power LED and the 7 segment ID LEDs on the mobile
rack unit switch off.

That's utterly weird.
This implies some trickery on the SCSI bus to control the display and power led.


To me this looks like either the disk is being reset explicitly by the OS,

Yeah, but that should not affect power.

or the power going down on the disk.

Which should not affect power to the chassis. If it does, all 5V must be down as well.

The first would imply improper termination, the second a broken mobile rack unit.

For me that is the same thing.
Unless the drive sits flush with the carrier and plugs directly into the chassis backplane
I think these things can't work due to too long stubs and too many connectors in the path.
Most of them can only work properly if you use them as end devices and terminate them
internally in the carrier with say an inline terminator.


What do you think?

I'd be grateful for any hints or suggestions concerning this issue...

Cheers,
Thomas

So, exactly where is the terminator for the drive end of the scsi bus?
There's nothing at the provided url that helps answer that question...

Nor any other question.
Like how many connectors in the stub from cable to drive.

The rack unit is right at the end of the bus. I thought the disk would
do automatic termination.

Since when do drives do autotermination.

So the question really is, do I need a
separate terminator on an LVD bus,

Of course you do
(unless these racks are configured like external cabinets with autotermination).

because the disk cannot do auto-termination in such a setup?

In no setup whatsoever. There are no terminators on LVD drives.
There are no terminators on SCA drives.

Auto termination you only find on external drive cabinets with in and out
connectors where the autotermination sits on the In/Out connector assembly.
.

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