Adaptec 2940UW with Fujitsu MAN3184M

[Marc D. Brooks]

Hello,

The Adaptec 2940UW is Single Ended. With Single Ended, there are a 
number of things to consider when trying to go Ultra. It is possible 
that even though the 2940UW initially negotiates for Ultra, the domain 
validation forces it to the slower rate due to issues seen with the 
communications. The other thing to check is if the 2940UW BIOS has been 
forced to the slower rate. Also with Single Ended, the SCSI Cable Length 
can be critical. Depending on a number of factors, going more than 2 
meters may add to the problem. The SCA-1 Adapter may also be adding to 
the problem unless it is known to be able to work at the Ultra burst 
rate in Single Ended. Also verify how you have the terminations. If 
these are the only two devices, the 2940UW must have its terminations 
turned on (automatic may be ok) and there should be a termination at the 
drive.

I believe the Fujitsu MAN3184M is Ultra160 Low Voltage Differential 
(LVD), and capable of automatically going down to Single Ended 
communications from LVD communications, like almost all LVD devices, but 
its not being used to its full potential by doing so. Changing to the 
29160 controller which is Low Voltage Dfferential (LVD) will help 
immensely in terms of being able to operate at a faster burst rate and 
being able to reliably support longer SCSI cable lengths.

Regards,
Marc D. Brooks

Baurzhan Ismagulov wrote:

>Hello,
>
>I'm using Adaptec 2940UW with Fujitsu MAN3184M, round Ultra-320
>terminated? cable (has a black box at the end), and a 68-pin to SCA-1
>adapter.
>
>When the driver is loaded, it says "FAST-10 WIDE SCSI 20.0 MB/s ST (100
>ns, offset 8)".
>
>1. Is it possible to make this combination work at 40 MB/s? Should I
>   recheck termination?
>
>2. Can I use the drive at 160 MB/s if I buy a 29160 controller (with the
>   adapter)?
>
>Thanks in advance,
>  
>