What is scalability?

Scalability:- Scalability is determined by the number of simultaneous clients served over a given period of time with a limited delay time

• The key determinant of scalability is Transaction Time
• Transaction Time doesn't mean good scalability - in fact it's the antithesis of it.

Example:-

• Case - 1 :- The response time of a page for 100 users is 1 sec, 200 users 2 sec and 500 users is 5 Sec
• Case - 2:- The response time of a page for 100 users is 4 sec, 200 users 4.5 sec and 500 users is 5 Sec

Now analyze Case - 1 and Case - 2. Which is scalable?

The answer is Case - 2. The reason is response times in Case - 1 are growing as we increase the number if users. Whereas in Case - 2 the response times are some what stable even if we increase the number of users. Now we will say the Case - 2 is scalable.