From owner-freebsd-scsi  Sun Feb 21 16:11: 4 1999
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From: "Kenneth D. Merry" <ken@plutotech.com>
Message-Id: <199902220010.RAA21911@panzer.plutotech.com>
Subject: Re: LVD transfer rate
In-Reply-To: <199902212320.AAA23952@qix> from Jean-Marc Zucconi at "Feb 22, 1999  0:20:46 am"
To: jmz@FreeBSD.ORG (Jean-Marc Zucconi)
Date: Sun, 21 Feb 1999 17:10:11 -0700 (MST)
Cc: scsi@FreeBSD.ORG
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Jean-Marc Zucconi wrote...
> >>>>> Kenneth D Merry writes:
> 
>  >> I have a jumper labelled `SE mode', and this jumper is ON, however the
>  >> drive does not work if I remove the jumper: the drive appears in the
>  >> SCSIselect utility, but it does not reports its capacity, and trying
>  >> to format fails (Not ready, asc/ascq= 40/80). 
> 
>  > That jumper forces it into Single Ended mode.
> 
> OK. this explain why I only get 40MB/s
> 
>  > What kind of cable do you have?  LVD drives don't have internal
>  > terminators.  You need an LVD cable (one of the "twisty" 68-pin cables)
>  > with a terminator block on the end.
> 
> I have the right cable, the terminator block is currently removed, but
> during my tests without the SE jumper, I got similar results with and
> without the terminator block.
> 
>  >> > I seriously doubt this is your problem, but I've got a machine at work with
>  >> > two 18G Seagate Cheetah II's on a Super Micro motherboard with an onboard
>  >> > 7890.  The problem is that the drives are SCA, and the SCA to 68-pin
>  >> > converters we put on them apparantly inhibit LVD.  So they only run at
>  >> > 20MHz instead of 40MHz.
>  >> 
>  >> No - connectors and cables are standard (80pins)
> 
>  > You have SCA disks?  Is the cable terminated?
> 
> The disk has a SCA connector. The cable is not terminated (the drive
> is currently at the very end of the cable).

You'll need to terminate the cable one way or another, because the drive
does not have terminators.

You might also check for bent pins on the cable; Justin has had trouble
with bent pins on some of his LVD cables.

Ken
-- 
Kenneth Merry
ken@plutotech.com


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