[SunRescue] Proper use of VME scsi controllers?????

[Greg A. Woods]

[ On , February 8, 2000 at 22:49:02 (-0000), jwbirdsa at carfallin.picarefy.com wrote: ]
> Subject: Re: [SunRescue] Proper use of VME scsi controllers?????
>
>    No, it's not. There was a Multibus SCSI/serial controller, used in the
> 2/120 and 2/170, but it was never placed in a Multibus-VME adapter. The
> sun2 SCSI controller as used in VME machines is just a 6U VME board in the
> 3x2 VME adapter -- just like the sun3 SCSI controller.
>    Perhaps you are thinking of the Xylogics 451 or other Multibus boards
> which were put into Multibus-VME adapters and used in VME machines.

Ah, but I have a sun2 501-1006 adapter in a Multibus-VME adapter and 9U
frame!  Maybe that's why I never got it to work under SunOS-4!  :-)

I'd forgotten all about there also being Sun-2 SCSI 6U VME cards too but
a quick glance at the old sun hardware reference FAQ has refreshed my
memory.
 
>    I keep hearing this story, and it may even be true, but the other thing
> I've heard repeatedly is people having trouble with the sun3 controller
> whereas the sun2 in the same configuration worked reliably.

The only problems I've ever heard about anyone having with the sun3
controller are under older versions of NetBSD where DMA either didn't
work, or wasn't reliable.

As the hardware ref. says: "Uses PALs and logic sequencers to implement
SCSI protocols." (as opposed to the "Sun-3" adapter which uses an
extremely common and quite reliable NCR5380 SCSI chip)

I've also compared benchmarks with friends running Sun-3s and "sc"
controllers and the differences were like night and day!

>    Sadly, nothing but SunOS supports the sun2 controller, which means that
> VME Sun-3 crates aren't very useful anymore. SunOS is getting just a bit
> too old and insecure; you can't run NetBSD with a disk because eventually
> you'll get one too many SCSI errors and eat your root filesystem; and you
> can't run NetBSD diskless because the ie driver is almost as bad as the si
> driver and has a similar tendency to crash the machine.

There's a half-complete sc driver for NetBSD.  It should be relatively
easy for anyone familiar with disk drivers under BSD to complete it.
It'll be a bit harder to get it to do DMA, if indeed that's even
possible with that card, but for tape drives the polling mode should be
just fine.

-- 
							Greg A. Woods

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