I am new to load testing ... wanted to understand what will be ratio of user we should run . I mean in my system we have 100 user hitting our system at a time . What should be my maximum user i should load for ... We have 100 user concurrent user in real life .. so to do regression testing to know what will me my worst case number of user .. is it 300 - 500 or more ..
It depends if you would like to run performance testing or load testing only. But basically if you would like to get performance metrics 100 concurrent users should be enough assuming that nobody else is using the platform when you run such tests. 100 virtual users is equivalent to your 100 real users if your user paths stick to real user journey.
Now if you would like to know how many users your infrastructure/application can manage with an acceptable response time before eventually crashing then you can consider load testing with much more users.
