Re: Why is my SCSI hard drive still running at 40 MB/sec?

Ar Q wrote
"daytripper" <day_trippr@xxxxxxxxxxxxxxx> wrote in message news:80dk145r15ldejoogld74ncl5lvp1eb03o@xxxxxxxxxx
On Thu, 1 May 2008 17:08:52 +0200, "Folkert Rienstra" see_reply-to@xxxxxxxx wrote:
daytripper wrote in news:hbhi149gfe40a47hide2dct9mfue876ljp@xxxxxxx
On Wed, 30 Apr 2008 23:26:56 -0400, "Ar Q" ArthurQ283@xxxxxxxxxxxx wrote:
"Michael Baeuerle" <michael.baeuerle@xxxxxxxx> wrote in message news:oomle5-004.ln1@xxxxxxxxxxxxxxxxxxxxxx
Folkert Rienstra wrote:
Michael Baeuerle wrote in news:le2je5-d81.ln1@xxxxxxxxxxxxxxxxxxx
Ar Q wrote:

All the SCSI hard drives I have are OK, not faulty in any way. How do I
know? When I got a new SCSI hard drive, I connect it to the internal
connector. They all run at 160MB/s. But when all drives are put in the
external enclouse, the speed drops to 40MB/s. That is I try to figure it
out.

Therefore the disks are OK and the upper byte of your SCSI bus must be
defective somewhere on your external equipment.

Not necessarily. The problem can be at both ends of the external cable.

A certain problem at the enclosure end that doesn't also affect the
SCSI controller wouldn't affect it either if it existed in the
controller itself.

Ack. "Upper byte broken somewhere on the way from the chip of the HA to
the external disk" should be more accurate.


Micha

I have duplicates for each part in the chain except the the SCSI control
card (Adaptec 29160). It is just the card performing perfectly except it
drops external segment to 40MB/sec. It is difficult for me to believe there
is a fault on the card itself. But it could happen.

Any way you can eliminate the enclosure completely, just hook a cable,
terminator and drive to the external HA connector and power it from the host
power supply somehow?

What you are effectively saying is that you don't trust the external connector
on the enclosure. He did say he changed the internal cabling twice and external
cabling once. He also said the controller is the only piece he has no backup for.
If that's to be true he has exchanged the external connector of that case twice
already with the internal cabling. Either that or he is lying.
If lying, then he knows very well that the problem is in the connector.

Frankly, I'm not sure what I don't trust in this long running saga anymore -
other than it has taken him an interminable amount of time to know
not-much-more than when he first posted.

He said the only thing he doesn't have a duplicate for is the host adapter,
and following the "kiss" principle, a quick-n-dirty configuration seems the
simplest way to eliminate (or finger) the host adapter as the root cause of
his problems.

Yes, I have used the kiss principle to eliminate one element at a time
except the host adapter. Acutally I did that before I asked the question.


If that isn't doesn't interest him, he could go the other way, and remove the
side panel from his host system, hook the enclosure to the internal connector
of his host adapter (which apparently works as expected) and put a known-good
bootable drive in the enclosure, and see what happens...


About the other way, it is a good idea.

Yeah, too bad that you don't have the faintest clue what he meant though.

However, all of my internal cables have termnators build-in,

Yeah, that is obviously a big problem when it's laying loose.

so it may not be a doable test for me.

Exactly. For anyone else it would be, but not for you.

Actually I am not sure about one thing.

One thing only huh.

What if one SCSI segment is not linear, but

And what segment exactly would that be?

like a "Y" with two ends?

A "Y" with two ends, now there's a new novelty.
You sure you don't mean a "V" with three ends?

On the one end, it ends with the terminator (internal cable terminator).
On the other end, it connects to a device (a hard drive and an internal
cable inside external SCSI enclosure) without the terminator.

Will this still be a valid SCSI configuration?

What if it isn't, would that be a problem for you? Not being able which one
of your two terminators to choose from, to put back to where it came from?

Hope some of you SCSI experts clear this out for me.

Boden, Heller and Schneider, to the rescue.

.

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