Fujitsu 2361's, SC7003's, 4.3BSD

[System Mangler]

In article <6387 at allegra.UUCP>, mp at allegra.UUCP (Mark Plotnick) writes:
> the SC7003 only provides RM05 emulations for the 2361 in the 64 sector
> configuration.  the hpmaptype() routines only handle alternate RM02
> emulations, though.

Use of the RM02 drive type is historical; Berkeley requested it.  It is
useless to VMS sites (who make up the bulk of Emulex's business), because
all they can patch in DRDRIVER is the geometry table for some drive type
that DRDRIVER already knows about.  In recent versions of VMS, that must
be one of RM03, RM05, RM80, or RP07, so emulations had better identify
themselves as one of those.

The problem is that hpmaptype() is trying to key off of the drive type
to see if it's "safe" to poke the holding register.  I think this isn't
necessary.  The holding register doesn't do anything useful, so it can't
hurt to poke random values into it, and if the controller isn't Emulex,
it should give you back whatever you poked it with (or at worst, zero),
which you sure won't find in your geometry table.  If you're paranoid
you might clear hpdc first.

So, for 4.3bsd, you want to move the RM02 differentiation code up ahead
of the SI check, and simply get rid of the insistence that it be an RM02.

> Also, everyone we've talked to thinks there's a limit of 2 Emulex
> massbus controllers per system, and a practical limit of 4 drives per
> controller.

Probably the limits of Ultrix.	Also, a Vmaster (CMI/SBI converter)
will only hold two controllers.  Do be sure to use short "A" cables
if you intend to daisy-chain lots of drives, the total must be less
than 100 feet.

The sector search "optimization" code, which is even more wrong in
4.3bsd, will degrade throughput when several drives are active on
one controller.  Set sc->sc_doseeks to disable this suboptimization.
Making it work correctly would require more cooperation between the
hp driver and the mba code, and isn't worth it.

Don Speck   speck at vlsi.caltech.edu  {seismo,rutgers,ames}!cit-vax!speck