[rescue] Wide disk on Narrow bus, reprise
md.benson at gmail.com
Sat Feb 9 11:56:04 CST 2008
On 9 Feb 2008, at 17:39, Curious George wrote:
> Hi, Mark,
> --- Mark <md.benson at gmail.com> wrote:
>> I have quite a bit of experience of using wide discs
>> on narrow busses,
> Great! :>
>> mostly in Macs and Amigas. In my experience, you
>> need to get hold of 2
>> things - a terminator for the end of the 50 pin
>> ribbon (and a ribbon
> Why does the ribbon need an extra terminator?
Wide drives don't have onboard terminators. 50-pin busses must be end
terminated (68-pin ones seem to work both ways in my experience
however, possibly they work LVD terminated and/or SE unterminated??).
I know that all the issues I've ever had getting wide drives working
that weren't down to dodgy Dell/Compaq firmware were usually to do
with not having terminator. You can substitute the terminator for a 50-
pin device with one onboard (how they would be setup from the factory)
but as the LX (AFAIK) ha
>> That's my 2p worth.
> It's my understanding that the drive should request
> wide transfers (negotiation) and, if the host
> declines, fall back to narrow. I.e., I don't see
> anything *wrong* with the approach I have taken...
I think the upper byte terminators in the adapters I have force the
drives down to Narrow mode by default, because the upper btye is
terminated at the back of the drive, and so no signal is passed
through it. I do have some adapters that aren't upper byte terminated,
come to think of it, that seem to work in most circumstances, but if I
know the machine is picky I'll use the upper byte terminated ones.
> I'll have to dig through the Standard to see how
> much of this is "optional" vs. mandated.
The biggest issue is SCSI is a non-standard standard. Controllers,
cabling, etc. vary so much between machines it's a black art getting
some of them to work. Sun stuff seems pretty hardy SCSI-wise. I've
hardly had any problems that weren't due to PEBCAK :).
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"Never send a human to do a machine's job..."
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