Cloud’s high availability myth

Public Cloud services are normally located in Telco grade collocation, best near public exchange points and supplied with high bandwidth connectivity. It should help for resiliency and high-availability, if the cloud operator chose the right design for his network and keeps track of routing and security issues. We found some locations to be not sufficient, though. So always have a deep look at Telco and ISP technology and inspect their high-availability concept.

Furthermore, you have to be sure your location is “always on” from where You have got access the internet: If you don’t have any connectivity to the internet, you won’t be able to connect to your data in the cloud. This may happen to yourself and all employees of your company at same time by simple wire cut. Just imagine: All of the company’s employees can’t access their data because it’s located in the cloud: A nightmare!

There are only two ways to avoid this:

  1. Either you keep your data on your own premises (which is a private cloud in fact), or
  2. Be sure to be dual homed (which connects you to two Internet Service Providers at same time).

If you choose to be dual homed be sure that you use 2 separate ISPs and be sure as well to use two different transport media, otherwise a wire cut by a digger would put you out of service again!

Best is some combination of two connectivity inlets of opposite direction to your building. If all this is not possible use a wired connection (Fiber or DSL) and a mobile backup. But always keep in mind: wireless often has fewer throughputs and much more interference / overbooking than wired connections.

So, before you run into loss of connectivity and unavailability of your data and services: Do a risk analysis for a public cloud scenario first before you run into trouble! Connectivity and availability on ISP side AND on company side is the main point to start the analysis. If either side isn’t highly available, don’t consider public cloud computing for mission critical business data!

We have pointed out some more details about dual homing here (in German language).

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