Sunday, October 28, 2012

Cloud and Shannon's Limit

I've been on the road (or air) so much over the past few months that some things I had thought I'd blogged about turn out to be either dreams or only to have hit twitter. One of them is Shannon's Limit and its impact on the Cloud, which I've been discussing in presentations for about 18 months or so. There's a lot of information out there on Shannon's Limit, but it's something I came across in the mid 1980's as part of my physics undergraduate degree. Unfortunately the book I learned from is no longer published so apart from a couple of texts that are accessible via Google I can't really recommend all of them (they may be good, but I simply don't have the context to say that with certainty). However, if you're looking for a very simple, yet accurate, discussion of what Shannon's Limit says, it can be found here.

So what has this got to do with the Cloud? In the context of the Cloud then put simply, Shannon's Limit shows that the Cloud (public or private) only really works well today because not everyone is using it. Bandwidth and capacity are limited by the properties of the media we use to communicate between clients and services, no matter where those services reside. But for cloud, the limitation is the physical interconnects over which we try to route our interactions and data. Unfortunately no matter how quickly your cloud provider can improve their back end equipment, the network to and from those cloud servers will rarely change or improve, and if it does it will happen at comparatively glacial speeds.

What this means is that for the cloud to continue to work and grow with the increasing number of people who want to use it, we need to have more intelligence in the intervening connections between (and including) the client and service (or peers). This includes not just gateways and routers, but probably more importantly mobile devices. Many people are now using mobile hardware (phones, pads etc.) to connect to cloud services so adding intelligence there makes a lot of sense.

Mobile also has another role to play in the evolution of the cloud. As I've said before, and presented elsewhere, ubiquitous computing is a reality today. I remember back in 2000 when we (HP) and IBM were talking about it, but back then we were too early. Today there are billions of processors, hundreds of millions of pads, 6 billion phones etc. Most of these devices are networked. Most of them are more powerful than machines we used a decade ago for developing software or running critical services. And many of them are idle most of the time! It is this group of processors that is the true cloud and needs to be encompassed within anything we do in the future around "cloud".

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