To use PAV dedicated devices, the guest must contain support for
managing and serializing the volume's data across the subchannels
– an exploiting operating system. z/VM® acts only as
the pipe between the guest and the hardware. Once the necessary
base and associated alias subchannels are attached to the guest, the
guest must manage their use.
In a dedicated environment, the performance benefits of PAV are
entirely up to the operating system running in the virtual machine. z/VM will not make
any attempt to optimize or alter the I/O flowing through the base
and alias subchannels. Note that real volumes cannot be dedicated
to multiple guests.
Figure 1 shows a typical example of a guest virtual machine
using two dedicated PAV volumes with one base subchannel and two alias subchannels
for each volume:
Figure 1. A PAV Dedicated Configuration: An Example
