[Info-vax] booting vaxstation off alpha

[Hans Vlems]

On 12 feb, 01:31, Johnny Billquist <b... at softjar.se> wrote:
> On 2013-02-11 13:44, Stephen Hoffman wrote:
>
>
>
>
>
> > On 2013-02-11 07:54:11 +0000, Hans Vlems said:
>
> >> DECnet over DSSI works fine, provided you get the incantations right.
> >> All I tried was CTERM and FAL and both worked as expected (reliable
> >> albeit slow).
> >> Another example of an undocumented, unsupported feature that works
> >> alright.
>
> > Not that there is even a remote chance of seeing DSSI gear around, nor
> > any likelihood of IP over FC nor connections, but...
>
> > If you ran any tests[1] with that, how well does that "albeit slow"
> > connection perform as compared with slow Ethernet?  CI wasn't known for
> > its network performance, as compared with DECnet over even then-current
> > 10 Mb Ethernet, and usual recommendations back then had CI at higher
> > cost as a backup connection.  I can't see DSSI being much better in that
> > regard.
>
> That sounds weird. Do you know why?
> I mean, CI was after all two redundant full duplex 70 Mbit/s channels,
> compared to the half-duplex 10Mbit/s ethernet. Not to mention the fact
> that the MTU of CI is much larger.
>
>         Johnny
>
> --
> Johnny Billquist                  || "I'm on a bus
>                                    ||  on a psychedelic trip
> email: b... at softjar.se             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol

Yes, I know what you mean Johnny. I don't think the CI was full duplex
though.
But it clocked a lot faster than ethernet. The cables BTW were
physically remarkably similar,
other than the colour. Won't say much for the electrical
characteristics of the two of course.
The CI bus was a lot more restricted in length than a 10BASE5 cable
which probably
explains the higher speed.
The DECnet driver for the CI bus (CNDRIVER) may have something to do
with the speed.
Perhaps DECnet slowed down the regular CI traffic too much so its use
was discouraged?
Anyway, speed wasn't a designfactor. Within the cluster all disks were
visible via the CI so
why use DECnet in the first place. Any other disk lived behind a host
on ethernet or another
DECnet link.
Hans