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Date:      Sat, 2 Mar 1996 11:36:08 +1030 (CST)
From:      Michael Smith <msmith@atrad.adelaide.edu.au>
To:        nate@sri.MT.net (Nate Williams)
Cc:        tomppa@fidata.fi, questions@freebsd.org
Subject:   Re: Backup problem
Message-ID:  <199603020106.LAA04099@genesis.atrad.adelaide.edu.au>
In-Reply-To: <199602292321.QAA13183@rocky.sri.MT.net> from "Nate Williams" at Feb 29, 96 04:21:38 pm

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Nate Williams stands accused of saying:
> 
> > My system hangs when I'm doing full backup to DAT drive with tar or
> > cpio.
> ...
> > it takes 5-55 minutes before it happens.
> ....
> 
> > I changed bt driver to aha (AMI SCSI controller is compatible with
> > buslogic 742a and Adaptec 1542). With aha driver backupping works like
> > a charm. Making full backup taked over an hour but it worked
> > smoothly. I even tried it twice. Any good explanations?
> 
> Yep, I'll bet the bounce buffer code is enabled on the aha driver and
> might not be on the buslogic.
> 
> >  > real memory  = 33554432 (32768K bytes)
> 
> This is important if you have more than 16MB and your card can't do DMA
> above 16MB.
> 
> >  > bt0: Bt747S/ 0-(32bit) bus
> 
> The bt driver assumes it can.

... and what hasn't been mentioned is that quite a number of EISA motherboards
(the 747 is an EISA board, right?) don't handle DMA above the 16M mark
properly (or at all).

> Nate

-- 
]] Mike Smith, Software Engineer        msmith@atrad.adelaide.edu.au    [[
]] Genesis Software                     genesis@atrad.adelaide.edu.au   [[
]] High-speed data acquisition and      (GSM mobile) 0411-222-496       [[
]] realtime instrument control          (ph/fax)  +61-8-267-3039        [[
]] Collector of old Unix hardware.      "Where are your PEZ?" The Tick  [[



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