Using 80 pin drives on a Fuel

[Tristram Scott]

Hi,

I have been trying to put an extra disk into my Fuel, and am running into a
bunch of troubles. My first difficulty is that all of my spare SCSI disks
are 80 pin, rather than the 68 pin that the Fuel is cabled for.

I thought that this shouldn't be a problem with the aid of a 80 -> 68 pin
adapter. However, I can't seem to get it to work with this setup. I put
the disk on, and then the prom hinv failed to report either the new disk or
the original (root) disk. I took off the original disk, and tried just the
new one, and I also tried using two or three other 80 pin disks I have, and
none of these configurations would show up. Hinv reports thathe SCSI
interface is there, but with no devices.

Out of desperation, I stuck the disk onto the other SCSI bus, using the 50
pin connector on my 80 -> 68 (-> 50) adaptor, and this time I can see it
and talk to it.

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.

Some of the disks I have are:

Seagate ST336706LW ( the existing root disk)
Seagate ST318305LC ( from a Sun array)
Seagate ST336605LC ( frommy Octanek)

My understanding from the Seagate web pages is that the LC and LW models
are the same beasts, just using a different set of connectors, so I really
thought these should all work.

The next trouble I had was that I was attempting to create a boot disk from
one of these new disks. Once I had it working on the 50 pin interface
(next to the CDROM) I managed to get sash64 and fx.64 to talk to it, and I
created a new partition and labelled it. That seemed to be okay.

After that, I wanted to create a new installation of Irix to it. I
unplugged the root disk from dksc(0,1,0), and then set the PROM
SystemPartition and OSLoadPartition variables to point at dksc(1,2,8) and
dksc(1,2,0), respectively.

I chose the Install option from the boot menu, and it installed the
miniroot, but this got to a certain point in the boot process then failed.
I didn't quite catch the full details, but the miniroot has installed, and
the system is booting up. It then reports a bunch of HARD ERRORs, pauses
for about five seconds and then reboots.

I think it said something about not finding what it wanted under the /hw
tree, but I didn't get a chance to note it down properly before it
rebooted.

I get the impression that it is suprised to be booting from something other
than dksc(0,1,0) and that I have not quite told it the new locationin all
the places.

Has anyone seen this sort of thing before?

The whole point of this process was to test the 6.5.29 CDs I cut with the
help of the mkefs script, as detailed on nekochan. I think they are okay,
since I can boot into fx, and also install a miniroot, but I would like to
be able to complete the whole process on a scratch disk before I
repartition my root disk and lose everything...

[Toni Grass]

Tristram Scott wrote:

[....]

Post by Tristram Scott
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

[Tristram Scott]

Post by Toni Grass
[....]

Post by Tristram Scott
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.

[Ivan Jager]

Post by Tristram Scott

Post by Toni Grass
[....]

Post by Tristram Scott
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.

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

[Tristram Scott]

Post by Ivan Jager

Post by Tristram Scott

Post by Toni Grass
[....]

Post by Tristram Scott
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?

Post by Ivan Jager
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.

[Tony 'Nicoya' Mantler]

In article <f_AJh.63$***@newsfe5-win.ntli.net>,
***@ntlworld.com (Tristram Scott) wrote:

: I
: had troubles the first time I tried this, with the disk showing up as every
: device rather than just device 1.

That's a SCSI ID issue. The ID of the device is the same as the controller (in
the case of SGI systems, the controller is at ID 0).


Cheers - Tony 'Nicoya' Mantler :)

[Tristram Scott]

Post by Tony 'Nicoya' Mantler
: I
: had troubles the first time I tried this, with the disk showing up as every
: device rather than just device 1.
That's a SCSI ID issue. The ID of the device is the same as the controller (in
the case of SGI systems, the controller is at ID 0).
Cheers - Tony 'Nicoya' Mantler :)

Hi Tony,

you were right on that one. Please ignore my ramblings about termination
and how I cleverly tricked it. Setting the SCSI ID correctly has allowed
me to connect the S1 array to the internal cable. I still don't believe
this is the correct layout for a SCSI chain, but it has enabled me to do a
quick xfsdump to disk, and then restore on the newly partitioned root disk.

Thanks to everyone for their helpful comments.

[Gary Heston]

In article <f_AJh.63$***@newsfe5-win.ntli.net>,
Tristram Scott <***@ntlworld.com> wrote:
[ ... ]

Post by Tristram Scott
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?

[ ... ]

Look on the adapter and see if there are some jumpers on it to set the
SCSI ID; a SCA drive expects the backplane it's being plugged into to
provide the ID jumpering. If you're not putting jumpers on, it's reading
that as ID 0, which is not going to work for you.


Gary

[Tristram Scott]

Post by Gary Heston
[ ... ]

Post by Tristram Scott
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?

[ ... ]
Look on the adapter and see if there are some jumpers on it to set the
SCSI ID; a SCA drive expects the backplane it's being plugged into to
provide the ID jumpering. If you're not putting jumpers on, it's reading
that as ID 0, which is not going to work for you.
Gary

Thanks Gary. I have been setting the SCSI ID, and don't think that is the
issue.

More strange, though is that the exisitng root drive in the machine does
not have a jumper set to give it ID 1, yet that is what it is working as.
I do find that a bit puzzling.