A big part of the messaging delivered at EMC VMware's 10th annual VMworld trade show last week surrounded the software-defined data center. No longer content to simply deliver compute virtualization tech, VMware is now actively pushing into both network and storage virtualization with the announcement of the VMware NSX software-defined networking stack and VMware Virtual SAN (VSAN). While NSX is primarily an evolution of the products acquired through VMware's purchase of Nicira, VSAN appears to be, for the most part, internally developed.
This isn't the first time VMware has ventured into the storage space. The VMware vSphere Storage Appliance was VMware's first attempt at a storage technology that actually leveraged the benefits of virtualization. However, the new VMware VSAN should in no way be confused with the maddeningly similarly named VMware VSA. The two technologies couldn't be more dissimilar. Where the VSA is a relatively limited appliance-based SAN stand-in that might be used in a small business or branch office environment, VSAN is a complete reintegration of persistent storage into the hypervisor.
However, VSAN is just a tool, and like all tools, it won't be perfect for everyone. Moreover, it's a tool that doesn't actually exist yet. VSAN will be in public beta shortly and will be compatible with the newly released vSphere 5.5, but isn't due out yet for some time. Despite its beta status, take a look at how VMware's Virtual SAN works -- it may be a glimpse into the future of software-defined storage.
What the VMware Virtual SAN isn't
It's easy to say that VMware VSAN is a way to leverage the direct-attached storage in VMware vSphere hosts to form a distributed, redundant shared storage infrastructure that vSphere can use to house VMs in place of a traditional SAN or NAS. However, that might lead you to believe it's similar to products such as VMware's own vSphere Storage Appliance or Hewlett-Packard's LeftHand P4000 VSA, which also fill that niche. That would be inaccurate.