Why do we use multi application server instances on the same server

Question

I guess there is a good reason, but I don\'t understand why sometimes we put for example 5 instances having the same webapplications on the same physical server.

Has it

Answer 1

Suppose you have a average configuration host and installed single instance of the web/app server. Now your application becomes more popular and number of hits increases 2 fold. What you do now ?

Add one more physical server of same configuration and instal the application and load balance these two hosts.

This is not end of life for your application. Your application will keep on becoming more popular and hence the need to scale it up. What's going to be your strategy ?

• keep adding more hosts of same configuration
• buy a more powerful machine where you can create more logical application servers

Which option will you go far ?

You will do cost analysis, which will involve factors like- actual hardware cost, Cost of managing these servers (power cost, space occupied in data center) etc.

Apparently, it comes that the decision is not very easy. And in most cases it's more cost effective to have a more powerful machine.