Troubleshooting SCSI problems -Reply
LAVARRE at iomega.com
Wed Dec 11 09:58:54 PST 1996
* From the SCSI Reflector (scsi at symbios.com), posted by:
* PAT LaVarre <LAVARRE at IOMEGA.COM>
You left out my favourite features I think?
Wasn't Verisys first to market with each of 4
features: field-programmable gate array, infinite
buffer, real-time display, and pricing below
US$5K/unit? No competition yet?
"Field-programmable" matters because you get new
real-time capabilities when you need them. For
example, we asked them to trace the activity of a
parallel port to SCSI tailgate a little
differently and they turned that around in a month
By "infinite buffer" I mean you can tell the
analyser to capture no data except for non-block
data, and then decide how to trigger AFTER you
capture a trace. The FPGA spills to h/w FIFO's
which spill to many MB of RAM which spill to disk,
on a laptop.
Yes you decide the trigger AFTER. This makes a
fundamental human difference. You only have to
capture a failure once - you don't have to make it
repeat. Questions like "how often and by what
opcode was this LBA accessed" become easy enough
to ask that you go get the answers and use the
info - rather than letting the difficulty of
discovering an answer persuade you to guess wrong.
By "real-time display" I mean you can watch slow
(e.g. electromechanical) interactions in real
time. Forget the read-the-old-data while
gathering-the-new-data approach. You can read the
new data as it is gathered.
Last pro - if you work for a sufficiently large
corporation, you may find the easiest way to
explain to Purchasing that you need a new laptop
is to buy it as a SCSI analyser.
Cons are a PCMCIA i/f, which means hassle with old
laptops, incomplete emulation of the usual Windows
i/f, which means finger glitches, and not quite
complete equivalence between what you can search,
what you can filter, and what you can trigger.
WHERE is the competition? (: Verisys price goes
back up every time they double the capture data
rate, then down only later. I hate that. :)
P.S. A fellow engineer just bought a pile of
ATA/PI analysers. I hope they have these feature
- don't quite know yet. I only know the ATA/PI
stuff doesn't even try to compete on price.
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