How do I size my cloud?
A cloud is not a cloud if it is not elastic. The elastic property of the cloud to expand and shrink based on demand is possible only with a proper capacity planning. I feel the most difficult exercise to do while making a cloud solution is capacity planning for your cloud. By this, I mean you have to size
- The managed environment as well as
- The management platform.
Most of the engagements that I’ve walked into might have some capacity or infrastructure that they want us to leverage and use it in the cloud. So the comparison becomes difficult if you don’t have a standard measuring unit for your infrastructure – for instance how do you know a Quadcore on an intel platform compares to power7 core. So I found a good explanation in this guide, in this interesting article –
The answer to the difficult question was to use something called the cloud CPU unit which is nothing but the computing power equal to the processing power on a one gigahertz CPU. When a user requests two CPUs, for example, they will get the processing power of two 1 GHz CPUs. This means that a system with two CPUs, each with four cores, running at 3 GHz will have the equivalent of 24 CPU units (2CPUs x 4Cores x 3GHz = 24CPU Units).
The other dimension of the complexity is to determine the resource needs and do the trends and forecasting. I typically collect the projections from the clients and then put down some critical assumptions to determine how big my cloud should be. Some critical questions that I typically ask
- How many concurrent users and peak users and what percentage of these users needs to be covered?
- What type of workloads they typically run – development, test ?
image attributes – mem, cpu, storage etc
IBM infrastructure planner for cloud made life easy for me that had a user friendly interface to take me through these steps and arrive at a sizing for the managed environment. Once we know the managed environment, we can make the sizing of the management platform. The details of how to plan the managed environment, I’ll discuss in my next post.
I’ll be interested in putting together the top 10 parameters
that are critical for sizing the cloud managed and management environment. Look forward to your comments.