On Fri, 5 Mar 2004, John Hudak wrote:

> Ahh yes, RK07 did have hardware support for dual porting...but...I don't
> think any of the DEC OSs took advantage of it..That was why I decided to
> write one in my spare time to run under RT-11.....waaaaaay long time ago....


RSX does. As does VMS. But it only uses it for two controllers on the same
machine. Dual-path disks. If you want to access a disk, and the controller
is busy, the OS will go to the other controller and try.

So: no loosely coupled MP machines that way...

Hmm, I wonder if not MP RSX could have the controllers on different CPUs
though... But I'm not sure if the I/O scheduler were smart enough to
always first try to use the local controller when there were to paths to
the disk.

Johnny

Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt@update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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