VMware recently released vSphere 5. One of the new features of vSphere 5 is something called a Storage Appliance. The vSphere Storage Appliance is targeted at small to medium businesses (SMB) and allows organizations to provides the storage benefits of shared storage without the cost and complexity of shared storage.
vSphere Storage Appliance runs on multiple servers simultaneously, so you can have the confidence that data is available to any of your workloads, even when a server fails. With vSphere’s availability features, you can restart snapshots of virtual machines automatically when a server fails, or use fault tolerant protection so applications run uninterrupted. Finally, perform maintenance with zero impact to the end user by migrating applications live from one server to another using vMotion.