[568] in linux-scsi channel archive
Re: Errors & Unit Attention
daemon@ATHENA.MIT.EDU (Rob Janssen reading Linux mailingl)
Thu Aug 31 00:13:13 1995
From: linux@pe1chl.ampr.org (Rob Janssen reading Linux mailinglist)
To: sdw@lig.net (Stephen D. Williams)
Date: Wed, 30 Aug 1995 23:55:45 +0200 (MET DST)
Cc: linux-vger@wab-tis.rabobank.nl, sdw@lig.net, bsa@kf8nh.wariat.org,
eric@aib.com, lnz@dandelion.com, linux-scsi@vger.rutgers.edu
In-Reply-To: <m0sno4l-0009yvC@sdwsys> from "Stephen D. Williams" at Aug 30, 95 10:25:10 am
Reply-To: linux-vger@wab-tis.rabobank.nl
According to Stephen D. Williams:
> I think a huge difference in reliability was mainly that I believe
> that all FD's use a type of active termination (which is so good I've
> even run without terminators) whereas the 1542a-c (I've fought with
> all three at various customers) had very finicky passive termination.
> I gave up ever getting more than 3 drives to work with Adaptec, but
> did it ages ago even with a FD950 (a $60 8-bit card).
My ISA-bus system has an Adaptec 1542B, and I never had a single problem
with it. The system has 2 disks, a tape and an external CD-ROM. I have
had a second external CD-ROM connected, as well as a third external
disk.
I know of other 1542B's that have 7 units connected.
Of course, in this configuration the controller has no termination at
all. However, both ends of the SCSI bus have passive termination.
> > Blown fuses are normally caused by misaligned connectors, not by the
> > host adapter itself.
>
> I don't think so in this case. The 8mm may have had a software problem,
> but after a while of successful data transfer, the 8mm activity light
> went solid and the fuse was blown. No problem with FD.
No, fuses are not blown because of software problems.
Some manufacturers (but not Adaptec) forget to put a diode in series with
terminator power. This may have been a problem on your tape drive.
Rob
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