How can I determine Breaking point of my Web application using JMeter? I have executed the JMeter Testplan with different concurrent users load. EX. 300 users(0% error), 400 users(7% error in a sample, 5% error in another sample), 500 users(more than 10% error in 4 out of 6 samples). At What value of % Error, I can say system reached the Breaking point.I used concurrent users 300, 400, 500 in a PHP website. Should I consider any other parameter to determine breaking point. How many maximum concurrent users my application can support?
Results analysis is not very obvious, you should consider checking following:
If the answers to all four questions above is "yes" you need to profile your application, check logs for time frame where JMeter sampler errors occur to determine what's wrong with it, perhaps profile it under load to determine which procedures are slow (i.e. search) and is underlying PHP code is good and can it be optimized, run "explain" on long-running database queries, etc.
After errors fix you may wish to check how does you application scale and how it survives long load, so called SOAK test. You may also check numerous docs on How to Analyze the Results of a Load Test query over the internet.