VSAN is a hot topic today! Without getting into the weeds, I want to briefly describe the similarities between these two technologies and how they can help enable your IT department followed by their differences.
Put simply, EMC products will be hypervisor agnostic and VMWare products will be storage agnostic. Ask anyone (including analysts, but probably not NetApp), and they’ll say that EMC and VMWare products work best hand-in-hand, but they are free to move about each others competitors. While this strategy can be a pain in the side of EMC and VMWare, it is ultimately a great source of power. This relationship holds true for ScaleIO and VSAN
Both of these technologies essentially do the same thing — build a virtual SAN. By using the storage presented to a group of hosts, a virtual SAN is created and then shared within a cluster. ScaleIO is hypervisor agnostic, and can even support physical servers. VSAN, on the other hand, is ESX specific. And the fact that these technologies are DAS, VSAN being ‘storage agnostic’ isn’t much of an advantage in this case. You could say VSAN is like ScaleIO if it was only licensed for VMWare…
There are other differences. Both technologies enable hybrid storage (e.g. a combination of spinning disk and magnetic) in different ways. They architecture is different (VSAN code is in the kernal where ScaleIO needs it’s own virtual machine). ScaleIO can scale larger today. And the list goes on.
Candidly, I believe ScaleIO is a better product because users of this product will have a lots of options in deployment and supported infrastructure. That said, if you are a VMWare only shop and you aren’t plagued with excessive scale, then you already have this code on your ESX clusters, you just need to license it.