1 :: What is Ramp-up Rate?

As mentioned earlier, Although your site may be handling x number of users per day, only a small percentage of these users would be hitting your site at the same time.

Therefore, when preparing your load test scenario, you should take into account the fact that users will hit the website at different times, and that during your peak hour the number of concurrent users will likely gradually build up to reach the peak number of users, before tailing off as the peak hour comes to a close.

The rate at which the number of users build up, the "Ramp-up Rate" should be factored into the load test scenarios (i.e. you should not just jump to the maximum value, but increase in a series of steps).

2 :: Why System Performance Monitoring Is Important?

It is vital during the execution phase to monitor all aspects of the website. This includes measuring and monitoring the CPU usage and performance aspects of the various components of the website, i.e. not just the webserver, but the database and other parts aswell (such as firewalls, load balancing tools etc.)
For example, one e-tailer, whose site fell over (apparently due to a high load), when analysing the performance bottlenecks on their site discovered that the webserver had in fact only been operating at 50% of capacity. Further investigation revealed that the credit card authorisation engine was the cause of failure - it was not responding quick enough for the website, which then fellover when it was waiting for too many responses from the authorisation engine. They resolved this issue by changing the authorisation engine, and amending the website coding so that if there were any issues with authorisation responses in future, the site would not crash.
Similarly, another e-commerce site found that the performance issues that they were experiencing were due to database performance issues, while the webserver CPU usage was only at 25%, the backend db server CPU usage was 86%. Their solution was to upgrade the db server.
Therefore, it is necessary to use (install if necessary) performance monitoring tools to check each aspect of the website architecture during the execution phase.

3 :: How To Report Load Testing Results?

Often the first indication that something is wrong is the end user response times start to climb. Knowing which pages are failing will help you narrow down where the problem is.
Whichever load test tool you use, it will need to produce reports that will highlight the following:
Page response time by load level
Completed and abandoned session by load level
Page views and page hits by load level
HTTP and network errors by load level
Concurrent user by minute
Missing links report, if applicable
Full detailed report which includes response time by page and by transaction, lost sales opportunities, analysis and recommendations

4 :: What Are the Important Aspects of Website Load Testing?

When testing websites, it is critically important to test from outside the firewall. In addition, web-based load testing services, based outside the firewall, can identify bottlenecks that are only found by testing in this manner.
Web-based stress testing of web sites are therefore more accurate when it comes to measuring a site's capacity constraints.
Web traffic is rarely uniformly distributed, and most Web sites exhibit very noticeable peaks in their volume patterns. Typically, there are a few points in time (one or two days out of the week, or a couple of hours each day) when the traffic to the Web site is highest.

5 :: How To Create a Load Testing Scenario?

Scripts should be combined to describe a load testing scenario. A basic scenario includes the scripts that will be executed, the percentages in which those scripts will be executed, and a description of how the load will be ramped up.
By emulating multiple business processes, the load testing can generate a load equivalent to X numbers of virtual users on a Web application. During these load tests, real-time performance monitors are used to measure the response times for each transaction and check that the correct content is being delivered to users. In this way, they can determine how well the site is handling the load and identify any bottlenecks.
The execution of the scripts opens X number of HTTP sessions (each simulating a user) with the target Web site and replays the scripts over and over again. Every few minutes it adds X more simulated users and continues to do so until the web site fails to meet a specific performance goal.