Emulex SC41 disc controller

[Chris Torek]

In article <1508 at goanna.oz> ejd at goanna.oz (Erick Delios) writes:
>We are looking at replacing [a UDA50+RAxx] with an SC41 controller.
>I can find no explicit mention that this controller works with under 4.3.
>
>Will this controller work on a Vax 11/750 ?
>If so will it work as well as a UDA  ?

We have one on a VAX 8250 running 4.3BSD-tahoe.  In a previous
incarnation it was a VAX-11/750.  Yes, it works; but maybe not with the
stock 4.3BSD driver.  (The 4.3BSD-tahoe driver is fine, obviously.)
There is also a bug in early firmware revisions on the SC41/MS that
causes it to hang a 750 such that only the little white `RESET' button,
or power cycling, unhangs it.  This bug shows only under heavy loads;
Emulex would not believe it existed until VMS V4.4 was sped up enough
that it showed there.

We have three CDC9771s on the controller.  Their maximum throughput
(from `dd if=/dev/rra?c of=/dev/null bs=63k') is lower than that of a
UDA50/RA81 (~600KB/s vs ~780KB/s) but their average transfer rates are
about equal.

Emulex support for the SC41/MS on the VAX 8250 is dismal.  In
particular, the EVM.EXE we have runs only on 750s, 780s, and uVAX-Is,
so the formatter cannot be used.  Emulex have told us that they will
not do anything for us unless we buy their new controller, the UD33;
they have not been very specific about what they will do if we do.
(One of these days I have to finish reverse engineering the monitor
and formatter, preferably *before* one of the CDCs dies.)

The UD33 has a whole 51 or 52 sectors of buffering, as opposed to
something like 10 or 20 on the SC41/MS.  (When will drive manufacturers
learn that an on board cache should mean numbers in *megabytes*, not
mere tends of kilobytes?)  It probably also handles XMD drives; the
SC41/MS will only do SMD.  Given the prospect of better support and
the ability to use newer (XMD) drives, the UD33 is probably a better
bet.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris