Advice on disk purchase?

[Brett Smith]

	Your disk drive is a Seagate Barracuda 9LP.  This drive has a
sustained throughput rate above 10 megabytes/sec with a maximum burst rate
above 15 megabytes/sec.  Your AHA-2940U should support 20 megabytes/sec in
narrow mode.  If the Seagate drive is the only unit on the SCSI bus, you
should get all the performance that the Seagate drive can offer.  Add any
other device to your SCSI bus and you start to degrade your achievable
performance since the Ultra narrow SCSI bus will be max. out between 15 to
20 megabytes/sec.  That's really not so bad!  The problem is mixing wide and
narrow devices on the SCSI bus.  Adaptec lost its focus a few years ago and
seems to have regained it again (I still believe Adaptec is the best choice
for SCSI).  It will take them a few years to get back to their flawless
past.  Also, some SCSI devices will give you a problem with wide negotiation
when attached to a narrow bus.  Seagate is not one of them.  It will work on
your narrow bus.  I would disable wide negotiation at the host adapter to
reduce the number of possible problems.  We use datamate cable adapters from
methode electronics for our cable conversion. Enjoy.


> -----Original Message-----
> From:	Piete Brooks [SMTP:Piete.Brooks at cl.cam.ac.uk]
> Sent:	Thursday, January 21, 1999 12:35 AM
> To:	Peter S Galbraith
> Cc:	Piete Brooks; AIC7xxx at FreeBSD.ORG
> Subject:	Re: Advice on disk purchase? 
> 
> > Which LVD should I get to put on my 50-pin 2940U controller (with
> > adapter):  ST39173LW or ST39173LC ?
> 
> I have "Vendor: SEAGATE  Model: ST39102LW        Rev: 0004"
> 
> > LW = 68-pin Wide SCSI connector, low-voltage Differential 
> 
> You should be able to use that one with a std "narrow <-> wide" cable or
> connector.
> 
> > LC = 80-pin Single connector SCSI connector, low-voltage Differential 
> 
> I don't know what this is (I just learn about the SCSI things I actually
> need!)
> but I guess this is one of the "SCSI + power" type connectors.
> 
> > So LW looks to fit a regular wide cable.
> 
> Yup -- that's the one I have and would recommend (out of ignorance)
> 
> > What's this 80-pin connector on LC?  Is this the new wave?
> 
> Pass -- anyone out there care to comment ??
> 
> > Thanks a bunch!
> [  Second time I've heard that recently ...
>    My impression is that this side of the pond, the normal interpretation
> of
>    that is somewhat different, i.e. it is usually sarcastic ....
> ]
> 
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