Estimating Number of Windows Azure Servers Needed

Question

I need guidance on how to compute, approximately, how many Windows Azure servers would be needed for 10,000 web users (assume 500 are on concurrently at any time). I realize that what the application does has a lot to do with this, but I need SOMETHING to reason through this and arrive at an order of magnitude answer. Assuming a medium-size, efficiently written web app, how many users per server is a reasonable expectation?

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David Pallmann, Director, .NET Application Development, Neudesic

Answer 1

Hello, I think the best answer can be found in load testing. Every application is different, and to find a proper configuration for you scenario, it is best to test it on your own. You can create a VM locally with a similar configuration of the cloud VM. You host the application in Development Fabric. Make sure you don't run too many background applications and services, and then perform a load testing.

You can also choose to do load testing directly in the staging deployment. This will give you more accurate results, but of course, you will have to pay for the extra bandwidth.

Anyway, I think if you don't need long running tasks (which are better to be handled by worker roles), 2 instances should be enough. According to http://www.microsoft.com/downloads/details.aspx?FamilyID=3bf7ecda-7eaf-4f1c-bbfe-cae19bc8bb78&displaylang=en, Dynamics CRM, a very complex application, can handle 500 concurrent users on an application server with 2 CPU cores and 4 GB memory without any problem. Yes, the matrix shows the database server is more advanced, but that alligns to storage service and SQL Azure rather than web roles. Also, we will provide you different configurations of VMs in the future.

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Answer 2

Thanks!

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David Pallmann, Director, .NET Application Development, Neudesic