Actually, you *are* using all the paths < the I/O subsystem in the hardware
is already aware of them if they are defined in your IOCP. An I/O presented
to the device by CP gets handed to the I/O processors. The I/O processors in
the frame handle deciding which path to use at any given point based on what
you told them in the IOCP gen.

There can only be one outstanding I/O to a device number at a time, but that
I/O can be (and is being) scheduled along whatever physical path is
convenient and available at the time the command goes out and comes back.

If you want to have more than one I/O outstanding at a time to the same
device, you have to use PAV. It's the only architected way to do this.
Z/OS is the biggest exploiter of PAV, but both Linux and VM know how to do
it too. 

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