VMware recently released a product the company is calling the vSphere Storage Appliance (VSA). VSA is targeted squarely at the SMB market in which customers may not have the means to purchase expensive high-end shared storage devices, such as SANs. SANs often require specialized knowledge and skills that may be difficult or impossible for the SMB to procure.
Simply put, VSA allows customers to transform spare local storage on a vSphere host into shared storage usable by any other host. In its present release, VSA supports up to three hosts in a cluster and supports features such as local RAID within the server and can mirror data between different servers for a higher level of resiliency.
For more information about VSA, take a look at the product’s FAQ page.