Mapping DMP meta-devices

Consistent mapping can be achieved from the host to the guest by using the Persistent Naming feature of DMP.

Running DMP in the host has other practical benefits:

Multi-path device can be exported as a single device. This makes managing mapping easier, and helps alleviate the 32 device limit, imposed by the VirtIO driver.
Path failover can be managed efficiently in the host, taking full advantage of the Event Source daemon to proactively monitor paths.
When Veritas InfoScale Solutions products are installed in the guest, the 'Persistent Naming' feature provides consistent naming of supported devices from the guest through the host to the array. The User Defined Names feature, or UDN, allows DMP virtual devices to have custom assigned names.

To map a DMP meta-device to a guest

Map the device to the guest. In this example the dmp device xiv0_8614 is mapped to guest_1.
```
# virsh attach-disk guest_1 /dev/vx/dmp/xiv0_8614 vdb
```

The mapping can be made persistent by redefining the guest.

# virsh dumpxml guest_1 > /tmp/guest_1.xml
# virsh define /tmp/guest_1.xml