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

[BSD Bob]

I was browsing my pile of ancient sun scrolls, and ran across some
early 3/4xx install/config manuals that stated to the effect that
a sun2 controller should only be used on servers with it only running
the 1/4 inch tape.  I thought that a bit perplexing, since I have run
my 3/xxx and 4/xxx boxes with sun2 controllers hacked with external and
internal bus lines, and they seem to work fine, as long as only one
pair of devices is hung externally, plus the internal tape.  The scrolls
suggest that such shennanigans are technically ``unsupported''.  It also
works fine on sun3 controllers.  So, my questions are:

1.  What are the approved ways to run both internal and external devices
    on the scsi bus on say a 12 slot deskside cabinet?  How many devices
    and how should they be hung?

2.  What are the approved ways to run two controllers, where one runs
    the tape, like a sun2 controller, internally, and the other, like
    a sun3 controller with external connector hacks runs the external
    bus.  Or, maybe run the tape and a pair of internal drives on one
    controller and external drives on the second controller.

3.  How does one get an internal tape and 4 external drives on one
    sun3 controller?  I get maxed out at 2-3 drives and tape before I
    start getting scsi bus busy errors.  ONE time I got 4 drives and
    tape up, but it was not real happy.  There has gotta be a way
    to keep the bus happy, and lots of devices hung thereon.

4.  What can the kernel stand in the way of multiple scsi controllers?
    And, how should they be set up?  I sense two, but somewhere I thought
    I saw in one fellow's hackers notes that it could handle 4, with
    proper jumpering and setup.

So, for the sake of discussion, hacking, and assorted suntoyz funzies,
my goal is to hang as many external and internal scsi whatzits on the
old 3/260 or 4/260 crate as I possibly can so I can make them a little
more usable as home bootservers and webservers.  All suggestions, etc.,
for the sake of community learning are most welcomely appreciated.

Thanks

Bob