Hyper-converged washing — which is the categorization of any combination of virtualization (compute) with storage irregardless of capability of the platform to manage compute and storage — is becoming prevalent. The market is flooded with scale-out solutions, all of which provide storage and compute in a single appliance. However, collapsing storage and compute into a single platform isn’t enough to claim a solution is hyper-converged.

Server SAN

Hardware and software vendors are heavily going after the very lucrative enterprise storage market. The research firm Wikibon has coined the term Server SAN and has written about its explosive growth. Server SAN is the concept of using x86 hardware to provide server virtualization capability and enterprise class storage. (In a future column, I will explain the differences between Server SAN and software-defined storage.)

Server SAN vendors have provided advanced features, including multiple data copies, deduplication, snapshot, and APIs for object-based storage. Most solutions use a scale-out architecture by which adding modular nodes grows storage and compute capacity.


I normally define hyper-convergence as modular appliances with the following attributes:

  • scale-out architecture;
  • converged storage and compute (networking is a plus); and
  • management overlay.

While Server SAN solutions provide a converged platform for scale-out storage and compute, the products don’t necessary provide a management overlay; this overlay provides a simplified method for deploying a new cluster or adding appliances to a cluster. Solutions in the Server SAN space focus on managing the storage portion of the converged system. For example, VMware’s VSAN enables administrators to easily add or remove existing vSphere nodes to/from a storage cluster; however, VSAN doesn’t provide an overlay for installing and managing the physical vSphere host and cluster.

To add a vSphere host, an administrator must first install ESXi on a new host and add that host to an existing cluster using the vSphere Web Client. Now the vSphere host can be added to the VSAN cluster.

In contrast, VMware’s EVO:Rail reference design does provide an overlay for managing the entire converged appliance. An administrator can unbox and deploy a cluster within minutes of racking and cabling a system. Systems from Nutanix, Scale Computing, and Symplicity all advertise a similar experience.


When comparing systems marketed as hyper-converged, it’s important to understand your desired use case. If the desire is to add SAN capability to an existing virtualization cluster, Server SAN solutions are the likely solutions. If the desire is to simplify the management of storage and compute, it’s important to ask potential vendors about the ability to manage storage and the hypervisor.

Have you considered a hyper-converged system or a Server SAN solution? If so, how were your experiences dealing with vendors?

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