Question

Hosting .NET application in Amazon EC2. what would be optimum
configuration for a group that has 525 employers and around 85,000 employees ? I am googling this for past 1 week but could not found a reliable solution

Answer 1

Perhaps you need to provide more information to get better answers – for example, what does your application do? How many users it has? What is the relevance of “525 employers and around 85,000 employees” – does it indicate amount of data or users? How many users will be concurrent at a time? What will be the average request time? What will be the usage pattern? How much memory it needs? Is your app CPU intensive or IO intensive? If its IO intensive, where exactly is your data stored?

Said all that, you need not worry too much from provisioning/scaling front. Amazon EC2 offers on-demand resourcing – so you can easily up-scale your configuration as per your need.

If you really want to find out optimal configuration, only way is to load test your application (with typical usage pattern/scenarios). Decide your parameters such as average response time and find out user limits served by say 1, 4 and 8 ECU (Elastic Compute Unit). You can load test using say standard instances – small, large and extra large. You can easily interpolate to project your actual ECU & Memory needs. Based on that you can choose actual optimal configuration.

You can try off-site load testing considering the fact that as per Amazon:

EC2 Compute Unit (ECU) – One EC2 Compute Unit (ECU) provides the
equivalent CPU capacity of a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon
processor.

You can arrange hardware equivalent of say 1, 2 and 4 ECU and do your load testing looking at memory consumption with performance counter. That should give you some clue as to what is needed. IMO, you will be better off load testing in actual EC2 environment.