High performance ASP.NET setup

Question

I would like to ask you what is the best setup for a following application:

ASP.NET 3.5 Web site - used as a presentation layer, a lot of AJAX and JS. Will not hit the server a lot.

ASP.NET WCF - sevice providing all data to the application. It's responsible for validation, data modeling / preparing and communication with the DB Server.

Database - SQL Server 2005 Std, some logic is coded on the server side as stored procedures. Some of the logic can be a bit time consuming. In my opinion it's the most resource consuming part of the app.

The website can have up to 1000 users per minute. We can have up to 4 servers in the following configuration: Intel Bi Xeon Quad 8x 2.00+ GHz, 16 GB RAM, SSD or RAID drives.

What is the best way to place parts of the application on the physical servers? Will they handle this kind of load?

Answer 1

The less scalable place in any application is database server, you can add more web and application servers but you can't replicate DB with the same ease so you will benefit in a long run if DB will not contain any logic especially any long running logic. In a lot of the applications limiting factor is not cpu but memory think about user sessions if you store 1mb of data per user you applications will be able to support 64,000 silmantanius user sessions with you machines it may be sufficient or not. Both problems can be mitigated by using application level caching but this can cause it own set of problems because now you faced with stale data. To scale session based sites you will need to use smart load balancer solution that supports sticky sessions, for your loads most likely you will need hardware load balancer.

Answer 2

In the application you describe, I suspect that thread management is going to be a big issue. Throwing hardware at the problem may not be the best approach.

In terms of partitioning, it depends on whether you can leverage things like caching and cache notifications. If every call to the app has to hit the DB and run a lengthy stored procedure, then you may want to have more DB machines and fewer front-end web servers.

This is a big subject. In an attempt to provide a reasonably comprehensive answer to exactly this kind of question, I ended up writing a book about it: Ultra-Fast ASP.NET: Build Ultra-Fast and Ultra-Scalable web sites using ASP.NET and SQL Server.