times, as shown in Figure 4.26. Basically, each virtual SAN sees each disk twice, once
for each of its paths to the storage, and then the virtual machine has two connections
to different virtual SANs, each telling it there are two disks! This would be the same
experience if redundant path iSCSI was used.
Figure 4.26 A view of a single disk without MPIO
Windows has a feature called MPIO that solves this and adds the intelligence into
Windows so that it understands that it’s seeing the same storage multiple times and it
has redundant paths. Install the MPIO feature and then run the MPIO tool. On the
Discover Multi-Paths tab, select the SAN device and click Add, and then you will be
prompted to reboot. Once the machine reboots, there will be a single instance of each
disk, as shown in Figure 4.27.
Figure 4.27 A view of a single disk with MPIO