Topic: Load,Stress and Volume Testing

Message

   What are Load, Stress, Volume, etc. testing?

				 Volume testing is a way to test functionality. Stress testing is a 

way to test reliability. Load testing is a way to test performance. 

Testing an application under heavy but expected loads is known as load 

testing. It generally refers to the practice of modeling the expected 

usage of a software program by simulating multiple users accessing the 

system's services concurrently. As such, load testing is most relevant 

for a multi-user system, often one built using a client/server model, 

such as a web server tested under a range of loads to determine at 

what point the system's response time degrades or fails. Although you 

could perform a load test on a word processor by or graphics editor 

forcing it read in an extremely large document; on a financial package 

by forcing to generate a report based on several years' worth of data, 

etc. 

When the load placed on the system is accelerated beyond normal usage 

patterns, in order to test the system's response at unusually high or 

peak loads, it is known as stress testing. Stress testing is often 

incorrectly used interchangeably with load and performance testing. 

In a stress test, the load is usually so great that error conditions 

are the expected result, although there is a grey area between the two 

domains and no clear boundary exists where you could say that an 

activity ceases to be a load test and becomes a stress test. 

There is little agreement on what the specific goals of load testing 

are. The term is often used synonymously with performance testing, 

reliability testing, and volume testing. 

Performance testing is usually performed to determine how fast some 

aspect of a system performs under a particular workload. It can serve 

different purposes: to demonstrate that the system meets performance 

criteria; to compare two systems to find which performs better; to 

measure what parts of the system or workload cause the system to 

perform badly. 

In the diagnostic case, we use tools such as profilers to measure what 

parts of a device or software contribute most to the poor performance. 

In performance testing, it is often crucial (and often difficult to 

arrange) for the test conditions to be similar to the expected actual 

use. 

A reliability test determines how likely a piece of hardware (or 

sometimes software) is to fail. It is part of reliability theory, used 

originally as a tool to help nineteenth century insurance companies 

compute profitable rates to charge their customers. Statistical models 

appropriate for any of these are generically called "time-to-event" 

models. Death or failure is called an "event", and the goal is to 

project or forecast the rate of events for a given population or 

probability of an event for an individual. 

Volume testing is used to determine if the system under test can 

handle the required amounts of data, user requests, etc. 

Soak testing occurs when running a system at normal to high levels of 

load for prolonged periods of time. A soak test would normally execute 

several times more transactions in an entire day than would be 

expected in a busy day. This should identify any performance problems 

that appear after a large number of transactions have been executed. 


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