Monitor Your Servers and Disks from a Single Spot, Don't Fret Over Losing a Disk
The more the merrier!
Perform CRUD operations on any of the servers. Upload files to any server. File storing and fetching is distributed across servers and disks.
Websites of the future will need to offer more and more computing resources to the user in order to compete. The sun sets on the days of running a top million ranked site off a single drive.