[rescue] 711 vs. 214 Sun Arrays

r. 'bear' stricklin red at bears.org
Thu Apr 3 13:24:50 CST 2003

On Wednesday, April 2, 2003, at 12:04  PM, Curtis H. Wilbar Jr. wrote:

> Ummm... I'm running a 12 slot enclosure on a 2940UW.  I believe it is
> running at 40mb/sec (which corresponds to 20mhz scsi clock).
> I've been running it almost 3 years without a hitch.

The problem is the AIC7800 does all kinds of sneaky stuff behind the
scenes with sync transfer rate negotiation. I would not be surprised at
all if it's cranked the speed down on the drives in that enclosure
without any obvious external indicator. I can't think of a tool that
Adaptec provides which reports the actual synchronous transfer rate
it's using on a particular drive.

I tried for a long time to get 20 MHz to work on my 12 slot (I've had
it for almost seven years). I used a DPT SmartCache IV, which is not as
sophisticated about negotiating synchronous transfer rates as the
Adaptec, but DOES include a tool that reports the actual negotiated
rate, and nothing in the 12-slot enclosure EVER worked reliably until I
cranked the bus clock down to 10 MHz.

FWIW, Sun also says "don't do it."

The 6-slot UltraSCSI model has a different slot flow with respect to
wiring than the 6-slot non-Ultra model, to bring it into line with the
more strict cable length and connector placement rules of UltraSCSI.

> How long was your SCSI buss ????  I have 3 internal devices, and the
> one 12 slot Multipack on maybe a 1.5 to 2ft cable.  Never had a problem
> with it.

Shorter, even, than yours. I had one internal DORS-32160UW and a Sun
.5m cable to the 12-slot enclosure.

> I think all the UltraSCSI spec models only offer 6 SCA connectors.  I
> think all the 12 drive multipacks are officially non "UltraSCSI",
> although
> YMMV as mine seems to work fine.

That is correct. All officially UltraSCSI-capable Multipacks (and
Unipacks) say so on the front, and there was never a 12 disk UltraSCSI


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