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Date:      Sun, 21 Feb 1999 15:23:57 -0700 (MST)
From:      "Kenneth D. Merry" <ken@plutotech.com>
To:        jmz@FreeBSD.ORG (Jean-Marc Zucconi)
Cc:        scsi@FreeBSD.ORG
Subject:   Re: LVD transfer rate
Message-ID:  <199902212223.PAA21380@panzer.plutotech.com>
In-Reply-To: <199902212218.XAA00376@qix> from Jean-Marc Zucconi at "Feb 21, 1999 11:18:58 pm"

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Jean-Marc Zucconi wrote...
> I just installed a LVD drive and the boot message reports only 40MB/s
> transfer rate. I expected 80MB/s  - did I something wrong ?
> 
> da1: <IBM DDRS-39130D DC1B> Fixed Direct Access SCSI-2 device 
> da1: Serial Number RE205733        
> da1: 40.000MB/s transfers (20.000MHz, offset 15, 16bit), Tagged Queueing Enabled
> da1: 8715MB (17850000 512 byte sectors: 255H 63S/T 1111C)
> 
> This is the only device on the LVD bus (Adaptec controller on a Asus
> P2BDS). I also have drives on the 50pin connector, but this should not
> be the problem ?

There are several things to check:

 - some drives have a single-ended-only jumper.  You should make sure the
   jumper settings are correct for LVD operation.

 - make sure there aren't any settings in the SCSI BIOS that would prevent
   things from going at LVD speeds.

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.

Ken
-- 
Kenneth Merry
ken@plutotech.com


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