I was reading Frank Denneman’s article with regards to new datacenter architectures. This in its turn was a response to Stephen Fosket’s article about how the physical architecture of datacenter hardware should change. I recommend reading both articles as that will give a bit more background, plus they are excellent reads by itself. (gotta love these blogging debates) Lets start with an out take of both articles which summarizes blog posts for those who don’t want to read the full article.
Top-of-rack flash and bottom-of-rack disk makes a ton of sense in a world of virtualized, distributed storage. It fits with enterprise paradigms yet delivers real architectural change that could “move the needle” in a way that no centralized shared storage system ever will. SAN and NAS aren’t going away immediately, but this new storage architecture will be an attractive next-generation direction!
If you look at what Stephen describes I think it is more or less in line with what Intel is working towards. The Intel Rack Scale Architecture aims to disaggregate traditional server components and then aggregate by type of resource backed by a super performing and optimized rack fabric. Rack fabric enabled by the new photonic architecture Intel is currently working on. This is not long term future, this is what Intel showcased last year and said to be available in 2015 / 2016.
The hypervisor is rich with information, including a collection of tightly knit resource schedulers. It is the perfect place to introduce policy-based management engines. The hypervisor becomes a single control plane that manages both the resource as well as the demand. A single construct to automate instructions in a single language providing a correct Quality of Service model at application granularity levels. You can control resource demand and distribution from one single pane of management. No need to wait on the completion of the development cycles from each vendor.
There’s a bit in Frank’s article as well where he talks about Virtual Volumes and VAAI and how long it took for all storage vendors to adopt VAAI and how he believes that the same may apply to Virtual Volumes and Frank aims more towards the hypervisor being the aggregator instead of doing it through changes in the physical space.
So what about Frank’s arguments? Well Frank has a point with regards to VAAI adoption and the fact that some vendors took a long time to implement these. However, reality is though that Virtual Volumes is going full steam ahead. With many storage vendors demoing it at VMworld in San Francisco last week I have the distinct feeling that things will be different this time. Maybe timing is part of it, as it seems that many customers or on a crosspoint and want to optimize their datacenter operations / architecture by adopting SDDC, of which policy based storage management happens to be a big chunk.
I agree with Frank that the hypervisor is positioned perfect to be that control plane. However, in order to be that control plane for the future there needs to be a way to connect “things” to it which allows for far better scale and more flexibility. VMware, if you ask me, has done that for many parts of the datacenter but one aspect that stills needs to be overhauled for sure is storage. VAAI was a great start, but with VMFS there simply are too many constraints and it doesn’t cater for granular controls.
I feel that the datacenter will need to change on both ends in order to take that next step in the evolution to the SDDC. Intel Rack Scale architecture will allow for far greater scale and efficiency then seen ever before. But it will only be successful when the layer that sits on top has the ability to take all of these disaggregated resources, turn them in to large shared pools and allows to assign resources in a policy driven (and programmable) manner. Not just assign resources but also allow you to specify what the level of availability (HA, DR but also QoS) should be for whatever consumes those resources. Granularity is important here and of course it shouldn’t stop with availability but applies to any other (data) service that one may require.
So where does what fit in? If you look at some of the initiatives that were revealed at VMworld like Virtual Volumes, Virtual SAN and vSphere APIs for IO Filters you can see where the world is moving towards fast. You can see how vSphere is truly becoming that control plane for all resources and how it will be able to provide you end-to-end policy driven management. In order to make all of this reality the current platform will need to change. Changes that allow for more granularity /flexibility and higher scalability and that is where all these (new) initiatives come in to play. Some partners may take longer to adopt than others, especially those that require fundamental changes to the architecture of underlaying platforms (storage systems for instance), but just like with VAAI I am certain that over time this will happen as customers will drive this change by making decisions based on availability of functionality.
Exciting times ahead if you ask me.