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Date:      Sun, 21 Feb 1999 23:55:44 +0100 (MET)
From:      Jean-Marc Zucconi <jmz@FreeBSD.ORG>
To:        ken@plutotech.com
Cc:        scsi@FreeBSD.ORG
Subject:   Re: LVD transfer rate
Message-ID:  <199902212255.XAA73327@qix>
In-Reply-To: <199902212223.PAA21380@panzer.plutotech.com> (ken@plutotech.com)

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>>>>> Kenneth D Merry writes:

 > 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.

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). 

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

It is set to 80MB/s

 > 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)

Jean-Marc


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