Well We Scaled Down Hitachi VSP
by Michael Hay on Oct 17, 2012
As per my last post we’ve scaled-down Hitachi Virtual Storage Platform (VSP) into a smaller form factor. I’d like to dig in a little deeper and explain why Hitachi Unified Storage VM (HUS VM) is dramatically different than our past efforts with scaled down enterprise platforms such as Universal Storage Platform VM (USP VM). My esteemed colleague Hu Yoshida discusses some of the key design points of HUS VM and its relationship to both VSP and HUS. In the past, and as Hu articulates in his post, we’ve followed a practice of miniaturization to take an enterprise storage system and make a physically smaller version of it. Essentially with USP VM and Network Storage Controller (NSC) before that, we kept the architecture the same, but we put less of the ingredients inside. So the miniaturized version was the same system with less cache, fewer processors, fewer ports, less on the backend, etc. in less space and a 19-inch rack. When we look at HUS VM we’ve rewritten the rules because rather than miniaturize the system we’ve scaled it down. Instead of using less of the same we’ve replaced key components with functional equivalents that are Hitachi value added or COTS (commercial off-the-shelf) in nature. The net is that the core hardware architecture of HUS VM is quite different than VSP, yet it still runs the same value-added block microcode as its bigger brother.
We were able to do this by improving our microcode relying more on COTS equivalents and a new Hitachi-specific microprocessor. Here’s an example: in the VSP system there are 5 types of Hitachi processors or ASICs, while in HUS VM there is only one type. These changes have increased flexibility in the microcode affording our customers the advantage of enterprise capability in a modular footprint. So unlike USP VM, HUS VM is not a miniaturized version of VSP, but instead it is a distinct class in the HDS portfolio apart from VSP. Additionally, if our users want a “miniature” version of VSP we have been able to accommodate that need since the release of the product. That is accomplished through our 3D scaling methodology allowing customers to configure a small VSP in a single 19-inch rack with or without mass storage and grow the system to the biggest, baddest storage system on the planet.
As suggested, HUS VM carries the same microcode base as its bigger brother leading to a clear benefit: consistent operational behaviors in the microcode from the biggest VSP to the smallest HUS VM. This can result in assurances of operational consistency across a larger part of the overall portfolio than in past. So specifically it means that not only are CLIs, APIs and GUIs the same but also the core engines like Universal Volume Manager (UVM), Volume Migration, Hitachi Dynamic Provisioning (HDP), Hitachi Dynamic Tiering (HDT), ShadowImage, TrueCopy, etc. operate in the same way on VSP and on HUS VM. Having been an IT administrator in a past life I know personally how big a deal this is. In effect it is like running the same Linux OS on a Hitachi 2U rack mount server or a blade server, which means I don’t need to be retrained, I don’t need to worry about switching my mental model when I move from one system to the other, and there is less of a chance for operational mishaps.