Before reading my take on this, please read this great article by Vijay Ramachandran as he explains the difference between ScaleIO and VSAN in the kernel. And before I say anything, let me reinforce that this is my opinion and not VMware’s necessarily. I’ve seen some negative comments around Scale IO / VMware / EMC, most of them are around the availability of a second storage solution in the ESXi kernel next to VMware’s own Virtual SAN. The big complaint typically is: Why is EMC allowed and the rest of the ecosystem isn’t? The question though is if VMware is really not allowing other partners to do the same? While flying to Palo Alto I read an article by Itzik which stated the following:
ScaleIO 1.31 introduces several changes in the VMware environment. First, it provides the option to install the SDC natively in the ESX kernel instead of using the SVM to host the SDC component. The V1.31 SDC driver for ESX is VMware PVSP certified, and requires a host acceptance level of “PartnerSupported” or lower in the ESX hosts.
Let me point out here that the solution that EMC developed is under PVSP support. What strikes me is the fact that many seem to think that what ScaleIO achieved is a unique thing despite the “partner support” statement. Although I admit that there aren’t many storage solutions that sit within the hypervisor, and this is great innovation, it is not unique for a solution to sit within the hypervisor.
If you look at flash caching solutions for instance you will see that some sit in the hypervisor (PernixData, SanDisk’s Flashsoft) and some sit on top (Atlantis, Infinio). It is not like VMware favours one over the other in case of these partners. It was their design, it was their way to get around a problem they had… Some managed to develop a solution that sits in the hypervisor, others did not focus on that. Some probably felt that optimizing the data path first was most important, and maybe even more important they had the expertise to do so.
Believe me when I say that it isn’t easy to create these types of solutions. There is no standard framework for this today, hence they end up being partner supported as they leverage existing APIs and frameworks in an innovative way. Until there is you will see some partners sitting on top and others within the hypervisor, depending on what they want to invest in and what skill set they have… (Yes a framework is being explored as talked about in this video by one of our partners, I don’t know when or if this will be release however!)
What ScaleIO did is innovative for sure, but there are others who have done something similar and I expect more will follow in the near future. It is just a matter of time.
