Dual porting UDA50 drives under 4.2

[Steven M. Haflich]

   I am considering dual porting RA81 drives between UDA50 controllers
on separate machines to support data-intensive applications.  Someone
with detailed knowledge of these devices and driver could save me days
of code-and-documentation reading:
   How does the UDA50 hardware handle a request on a drive which is busy
executing a command from its other port, and would this condition blow
away the standard 4.2 driver software?
   Also, does the hardware support dynamic locking of a drive by one or
the other port under *program* (not pushbutton) control?
   Respond by mail and I'll summarize.  But *please*, my question
concerns details of hardware capability and driver support.  I *don't*
need to be told why Unix file systems cannot be mounted shared (unless
both machines mount read only), etc.  Thanks in advance.

Steve Haflich
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smh at mit-ems@mit-mc