Scalability for Web applications
What is scalability?
In simple terms, the server should be able to meet the increased demand for HITS per SECOND/ Transactions per Second over a period of time in increasing user ratio, without failure.
If the Hits per second decreases at some point of time, then it is indicative of decreased performance. Typically a decrease in scalability can be traced to database indexing problem, a full data cache or a saturated network connection.
Therefore it becomes necessary to test the disk usage, memory, or network components while stress testing.