I have now been running instances in the AWS Cloud for about 6 months now. Granted they are not being used much, but it has made me think long and hard about how to deploy this technology within normal landscapes, what are the Pros and Cons as well as the gotchas
So I would like to start with a simple compare and contrast of each system –
Compute Units – AWS instances are not flexible in terms of the choices of resources. The IBM p-Series is much more flexible in terms of CPU and RAM allocation.
Whilst I initially saw this as a negative, I actually see it as a positive. The concept of Utility computing is that you have discreet, but known sizes of Compute Units, then you can startup or shutdown these units to provide computing power in steps.
Operating System availability – On a standard server you can use any O/S your hardware is capable of running, AWS restrict O/S availability. Granted there are hundreds of Linux/Unix AMI’s but there is not a great selection of Windows AMI’s (Windows 2008 Server has only recently become available.)
Infrastructure Allocation – On a standard server allocating or subtracting resources is usually a specialist task, when was the last time you were able to remove a 100Gb SAN volume from a server in 5 minutes? On AWS instances you can provision an amazing array of infrastructure, very easily and quickly.
Geographic regionality and legality – With a normal hosted server, you know the location and most of the legal restrictions upon you and your data, with the AWS cloud you cannot be so sure. Whilst you may be aware of the region (eg EU-WEST-1) the exact location is unknown. This means that the exact legal status of your servers is not immediately obvious, this would bear scrutiny from your legal teams.
(Although if you logon to the server and open Google in a web browser, the regional settings picked up from IP address is a give away. I got Google Ireland, which puts the instance in City-West Dublin)
This is by no means an exhaustive list, and I will probably add to it as time goes on and I think of more.