On Mon, 12 Apr 1999, Dr. Robert J. Meier wrote:
> SCSI Linuxers,
>
> Thank you for your time and any help you can offer.
>
> What SCSI hard drive/host adapter combinations are people
> using successfully?
>
> Has anyone had experience (good or bad) with a Seagate SCSI
> hard disk and Adaptec host adapter?
>
> I had been watching this list for several months and in January
> purchased a
>
> 9G Hard Disk Ultra Wide SCSI 2
> Seagate Model: ST39173LW Rev: 6246
> Type: Direct-Access ANSI SCSI revision: 02
> Ultra Wide SCSI 2 Host Adapter
> Adaptec AHA2940
> Adaptec AHA274x/284x/294x (EISA/VLB/PCI-Fast SCSI)
> 5.1.10/3.2.4
>
> It passed the smoke tests after installation, but after 6
> weeks, I have traced chronic intermittent failures to unreliable
> reads. I can duplicate the problem by simply reading the same
> image (3000 copies of the same 300K file) multiple times.
> A comparison (cmp(1)) of the copies fails 1-5 times per 3000.
> The count of comparison failures is fairly steady, but the
> particular comparisons that fail (0370, 1120, etc.) during each
> set of 3000 is different.
>
> I believe that the write operation is error free, but that
> the read operation fails approximately once for every 100 MB
> read.
>
> I have switched the operating system from linux-2.2.1 to
> linux-2.2.5. The problem also occurred under Windows95. I have
> upgraded the support packages listed in the Changes file for
> linux up to the latest available on the internet.
>
> The only common piece that I see remaining is the read
> amplifiers in the hard disk.
>
> Is there something I'm missing?
> Are there any suggestions?
>
> Thank you,
>
> Bob
The ST39173LW is a Barracuda, which is a very reliable drive if it is given
adequate cooling. Similarly, the AHA2940UW is a well proven host adapter,
but is noted for being exquisitely sensitive to proper cabling and bus
termination. The usual effects of any sloppiness in these areas are
unreliable data transfers such as you are experiencing. One area that
causes a lot of problems and is easily fixed is the use of automatic
termination in the Adaptec setup firmware. This is the spawn of the Devil
and should be avoided at all costs. You know (or should know) your bus
configuration, so tell the board what it should be. Then be sure that the
physical far end of the bus (and ONLY the far end) has a quality terminator
and access to TRMPWR. And make sure that the topology of your bus is a
single line with no branches. And examine your cables for nicks and
possibly broken wires. These simple steps should go a long way toward
eliminating the problems that you are seeing. It certainly could be a
problem within the electronics of the drive, but Occam's Razor would
indicate that it is much more likely to be a bus problem.
Harvey
----------------------------------------------------------------------------
Harvey Fishman |
[EMAIL PROTECTED] | A little heresy is good for the soul.
718-258-7276 |
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