Re: scsi disk question: u2w vs. uw
Yes, I believe you can. You can set the transfer speed in the
setup of the AHA2940 card from CNTRL-A at boot up. You can also use SCA
drives with either UW or U2W, if you can obtain these. They have 80 pins
and need external termination and ID setting, but there is an adaptor that
you can buy for around 12 pounds (sterling) that allows connection at
either 50 pin or 68 pin. It also allows you to set the ID.
Also see 'http://ask.adaptec.com/cgi-bin/tic/faq'
This is what Adaptec say about the different types of drives:-
What's the difference between SCSI-1, SCSI-2, Fast, Wide,Ultra Wide,
and Ultra2? (Article #990426-0019)
Description:
What is the difference between SCSI-1, SCSI-2, Fast, Wide,
Ultra Wide, and Ultra2?
This information applies to the following product(s):
- 1505 series, 1510 series, 1515, 1520 series, 1530p, 1540 series,
2902, 2906 series, 2910 series, 2920 series, 2930 series,
2940 series, 3940 series, 2940U2W series, 2930U2 series, 3950U2 series
This information applies to the following Operating System(s):
- All/PC, Mac OS
Solution:
The primary difference is in the command set used in the SCSI
standard and the bandwidth, or maximum available speed of the devices.
SCSI-1 5MB/Sec 8 bit SCSI bus
SCSI-2 5MB/Sec 8 bit SCSI bus
SCSI-2 Fast 10MB/Sec 8 bit SCSI bus
SCSI-2 Fast Wide 20MB/Sec 16 bit SCSI bus
SCSI Ultra 20MB/Sec 8 bit SCSI bus
SCSI Ultra Wide 40MB/Sec 16 bit SCSI bus
Ultra2 Wide 80MB/sec 16 bit SCSI bus
Ultra2 speeds are available only when a Ultra2 host adapter is
connected to Low Voltage Differential (LVD) devices on the LVD/SE
port. If a single-ended (SE) wide or narrow SCSI-2 device is connected
to the LVD/SE port, the performance for all devices reverts to SCSI
Ultra.
HTH JohnG
32865e97b5342e762ab140e00f3da23b - Just 'Debian'
On Tue, 23 May 2000 iehrenwald@earthlink.net wrote:
> On Tue, 23 May 2000, John Gould wrote:
>
> > Sorry, but this is rubbish! The SCSI controller will have no effect on the
> > disk rotational velocity. However this is not what the poster asked! If
> > you put an Ultra 2 wide on a non wide channel the transfers will be eight
> > bits at a time instead of 16, i.e. half the speed, but it will work
> > fine. Some cards like the AHA2940UW have a wide and a narrow channel, if
> > the Ultra wide disk is put on the UW channel and the Ultra disk is on the
> > standard channel there will be no effect on performance.
> >
> > HTH JohnG
>
> On a somewhat related note.. I have a 2940UW. Can I use a 50 pin Ultra2
> drive on the 50 pin Narrow channel? I know I wouldn't get U2 speeds, but
> the 50 pin narrow channel is all I have to use. 68 pin UW is too
> expensive and hard to find these days. I can find 50 pin Ultra2
> 18 gig drives for pretty cheap. Thanks.
>
> Ian
>
>
>
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