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Re: Hard drive cable question -



On Thu, 2006-02-23 at 17:41 -0500, bobgoodwin wrote:
> Mike McCarty wrote:
> 
> > bobgoodwin wrote:
> >
> >> Mike McCarty wrote:
> >>
> >>> bobgoodwin wrote:
> >>>
> >
> > [snip]
> >
> >>> If you use M/S jumpering on the drives, then in theory it doesn't 
> >>> matter
> >>> where you connect them.
> >>
> >>
> >>
> >> Except it appears to me that it matters as far as terminating the 
> >> line properly is concerned.  Ideally it would seem the termination 
> >> should be at the far end where the master is connected to avoid the 
> >> possibility of a mismatch at the end of the stub that would result if 
> >> the slave is at the far end.  How much ringing might occur and the 
> >> severity of it's effect is an unknown?  It would be interesting if I 
> >> could get into the circuit and poke around with a scope probe ...
> >
> >
> > Agreed.
> >
> > [snip]
> >
> >
> >>>> I thought "cable select" cables had wires obviously crossed in the 
> >>>> ribbon cable but that may not be true with this 80 wire ribbon?
> >>>
> >>>
> >>> Not crossed. For CS, the drives have resistive pull-ups on them. The MB
> >>> pulls down one line. The wire to this line is *severed* as the slave
> >>> connector, so the "master" sees a high, while the "slave" sees
> >>> a low on this pin. (The MB may have a pull-up and the drives
> >>> a pull-down, I forget the polarity.)
> >>>
> >> If the h/d manufacturer provided this explanation this thread would 
> >> never have started.  I would have never asked any questions.  It appears 
> >
> >
> > Well, just how much of the interface should they document? Each pin?
> > Just the Cable Select pin?
> >
> >> that I probably have cable select which I will try here in a little 
> >> while.  The drives can be jumpered for CS and I have 80 wire ribbon 
> >> cables so it appears that should work if I understand everything I've 
> >> read here?  It would be helpful if the user knew that he was dealing 
> >> with a c/s cable, there is no mark apparently other than the fact 
> >> that there are more wires than connector pins to tie them to?
> >
> >
> > Color of the connectors. Usually non-CS cables use just one color
> > of connector, presumably because they can get better volume
> > prices that way. CS cables are supposed to use blue for the MB
> > connector, black for "master" and grey for "slave", IIRC.
> >
> > Mike
> 
> Ok, I jumpered the drives c/s and the computer can deal with that.  As 
> long as the one set up for FC4 is on the master connector it boots and I 
> can see the second drive.
> 
> The problem arose from the fact that I suspected an intermittent drive 
> problem.  Apparently the failure was on the Windows drive while I was 
> only using FC4 and MySql!  I ran smartctl and it indicated that both 
> drives had a lot of use on them. One looked like more than four years 
> power on time!  I assumed it was the bad drive and rep[laced it with 
> another low time drive I had and then I began to have trouble.  The 
> computer would not boot no matter what I tried.
> 
> Now I pulled the one I thought to be usable [but is bad, I just tried it 
> again] and replaced it with the "bad" drive I had set aside and the 
> computer will boot FC4 with that drive plugged into the c/s master 
> connector.  Hwbrowser and fdisk show both drives.  So next to start over 
> and install W2k on the other drive, I guess Windows will want to be the 
> master and I will most likely wind up reinstalling FC4 with grub in the 
> MBR on the Windows drive.
> 
Windows *prefers* to be the master.  It should be the only drive in
place when you do the install.

Grub has options that allow the use of a windows drive as the slave with
your fedora drive as the master. (see the map and chainloader
commands). 


> If nothing else I have learned something about configuring hd and their 
> jumpers ...
> 
> The information has been helpful and appreciated.
> 
> BobG
> 
> 


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