Re: Using 80 pin drives on a Fuel

Ivan Jager <aij+nospam@xxxxxxxxxxxxxx> wrote:
On Sun, 11 Mar 2007, Tristram Scott wrote:
Toni Grass <toni@xxxxxxxxx> wrote:
Tristram Scott wrote:

[....]
Does anyone have any suggestions as to what might be the problem with
doing
this on the 68 pin cable? I was quite prepared for it to wok the whole
bus
single ended rather than LVD, but it doesn't even want to do that for
me.

I think, you should use an adaptor which is really LVD (which means no
50 pin connector) and you have to care for the correct SCSI ID

Toni

Thanks Toni. I had wondered about this, and I am attempting to track down
such an adaptor. All my reading, though, indicates that it should be
perfectly possible to put a 50 pin device on and LVD chain, but it will
force the whole chain to work as single ended. Unfortunately, I am not
even seeing this. Hinv reports the adaptor, but no devices at all.

I'll look for an 80 -> 68 pin adaptor this week. The place I visited on
Friday was out of stock, and I had expected the [80, 50] -> 68 would be
fine.

Well... I visited another branch of Maplin, and purchased their SCSI-SCA
LVD Adapaptor. This shows the same symptoms. If I connect a drive to the
68 pin chain with it then no devices show up in the hinv. Grrrr. It seems
that something better is required to make this work. Does anyone know of
an adaptor which definitly works with an 80 pin SCA drive in the Fuel?



Putting a 50 pin device on a wide bus should be fine. Connecting two wide
devices over a 50 pin cable will cause trouble, because they will try to
negotiate the fastest connection they both support, and then the cable
will drop half the bits.

IIRC using any SE device on an LVD bus will force the whole bus to be SE,
but I don't know whether SE adapter would count as a device. I could
imagine the adapter grounding what it thinks should be ground, but the LVD
devices trying to speak LVD because there aren't any SE devices on the
bus.

Ivan

Thanks Ivan. That was my understanding too. Connecting SE devices should
work, it will just make the whole chain drop down to SE mode. Clearly the
adaptor in the Fuel can cope with this because the other adaptor in the
Fuel is connected to a 50 pin cable for the CD.

On a more positive note, I have managed to connect something. I fed the
internal 68 pin cable to a Sun Storedge S1, which is a rackmount box for up
to three disks. The S1 does auto termination, and a few other tricks. I
had troubles the first time I tried this, with the disk showing up as every
device rather than just device 1. I think this was a termination issue. I
then stuck the cable on the out SCSI port rather than the in one. My
thought here was that perhaps the S1 would notice that the cable was already
terminated on the out side, and so not bother with doing its own. This
seemed to work, and I have managed a full and happy install of 6.5.29 with
the CDs I cut, so that is great.

By the way, I do _not_ recommend attaching an array of disks part way along
a cable like this. The SCSI devices are supposed to be in a single chain,
not in a branching chain as I ended up with. It worked for me for my
installation tests, but I don't suggest it as a proper solution.


--
Dr Tristram J. Scott
Energy Consultant
.

Relevant Pages

  • Re: 68 pin LVD wide drive on fast SCSI II 50 pin bus?
    ... Will connecting an LVD wide drive to a Fast SCSI II controller be ok? ... with a correctly wired adapter it should work as ... The wide LVD drive must see Pin 16 ...
    (comp.periphs.scsi)
  • Re: Using 80 pin drives on a Fuel
    ... Toni Grass wrote: ... single ended rather than LVD, but it doesn't even want to do that for me. ... you should use an adaptor which is really LVD (which means no ... 50 pin connector) and you have to care for the correct SCSI ID ...
    (comp.sys.sgi.hardware)
  • Re: Using 80 pin drives on a Fuel
    ... single ended rather than LVD, but it doesn't even want to do that for me. ... 50 pin connector) and you have to care for the correct SCSI ID ... Hinv reports the adaptor, ... Putting a 50 pin device on a wide bus should be fine. ...
    (comp.sys.sgi.hardware)
  • Re: 68 pin LVD wide drive on fast SCSI II 50 pin bus?
    ... Will connecting an LVD wide drive to a Fast SCSI II controller be ok? ... That also depends on the SCSI host adapter. ... The wide LVD drive must see Pin 16 ...
    (comp.periphs.scsi)
  • Re: Parallel Cable IV in Spartan 3E???
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