Re: Ultra 60 SCSI External Interface

On 2009-02-13, rkiesling <> wrote:
>
> Hello, all,
> I would like to find information about terminating an Ultra
> 60's external SCSI interface.

Do you have any drives connected to it? I've had no problems
with using the U-60 both with and without external drives.

As others have said, if you have nothing connected to it, it
should not give any errors at all.

If what you have connected to to is in the Sun UniPack,
MultiPack, or the (relatively rare) two-drive FlexiPack, the housings
are self terminating. If you have nothing connected past the last
68-pin one, you should see two LEDs on the back ("Hi" and "Lo") lit up.
The UniPack holds a single drive. The FlexiPack can hold two -- or a
full-height 5.25" drive such as some tape drives. The Multipacks can
either hold 6 1.6" high SCA drives, or 12 1" high drives (you can put
six of the 1" drives in the 6-slot MultiPack, but not put any 1.6" tall
drives in the 12-slot MultiPack. (I've used both at different times.

If you have a 50-pin cable going to another device, it will
auto-terminate the upper half of the SCSI Bus (and light the "Hi" LED
only. You may well need an external 50-pin terminator on that 50-pin
device, since most drive boxes with 50-pin connectors tend to not be
self-terminating (at least the Sun ones which I have used), you would
need a 50-pin terminator on that too.

And note that the 68-pin external SCSI bus on the back of the
U-60 is SE (Single Ended) SCSI, not LVD (Low Voltage Differential) or
HVD (High Voltage Differential), so the drives must match. Most LVD
drives can pretend to be SE without problems (excluding some Exabyte
Mammoth-2 drives such as those in the EXB-430), but connecting HVD
drives to a LVD interface is likely to damage something.

So -- make sure what kind of external drives you have.

> The system occasionally tries
> to write and reset the SCSI device, and then times out with
> a failure.

To write to what? There are two internal SCA drives
(auto-switching between LVD and SE, but they are on the internal bus.
Also on that bus is the CD-ROM or DVD-ROM (if there is one in the
system), and possibly a tape drive of some sort. These are narrowed
down to 50-pin, while the SCA drives are 68-pin. There is likely to be
a terminator at the final CD-ROM connector.

> I cannot find information in the Sun docs about
> whether an external terminator is needed if there are no
> devices attached to the port,

It is not.

> or about the SCSI termination
> on the mainboard,

That is automatic, and you can forget about it.

> if that is only related to the internal
> SCSI assembly. ISTM the external port should be
> self-terminating, but I'm only guessing.

It is self-terminated on the inside end, but you do need to
worry about termination of some form if you hook up external drives. It
depends who made the external drive boxes.

> On a related note, are there any opinions about which
> outboard SCSI disks would be fast enough not to unduly slow
> down the system (2 x 450 Mhz UltraSPARC, 1GB RAM) for disk
> intensive tasks.

I think that you will be fine with any SCA interface drives in a
MultiPack or in several UniPacks.

> TIA. Replies here or with an e-mail message, please.

Here -- from me. It is awkward to send e-mail from within news.
I need to be on a different system for that.

Enjoy,
DoN.

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