Load Runner Analysis and types of graphs

First let's see what is Loadrunner Analysis and then see some important loadrunner graphs.

Analysis:

• Analysis is the utility or program to analyses the LoadRunner results in a very detailed manner.
• LoadRunner results are saved in .lrr file(lrr stands for Loadrunner Result) and can be viewed using Analysis.
• Analysis gathers the result information from scenario results (lrr file) and stores the information in form of .lra file.
• LoadRunner result has “Log” folder which contains Vuser logs and saves snapshots on error.
• Analysis generates Analysis Summary for the test which gives good idea about the test.
• Analysis generates graphs from the data collected during the test execution.
• Few of the graphs which are important for analysis of the results are Running Vusers, Hit per second, Throughput, Transaction Summary, Average Transaction Response Time, Error per second, etc.
• Analysis provides the raw data from which graphs are created.
• The granularity of graph should be such that it has maximized readability along with accurately represent important events.
• Analysis also provides facility to compare the results for the test.
• Analysis has good reporting mechanism which is helpful in sharing the test results.
• In Analysis, customized templates can be created to generate the same report for other test results.
• Loadrunner provides many formats to save the report. You can save you result in HTML format and share with the clients.

Graphs:

There are many types of graphs in Loadrunner results but you see only the default one when you load the results. Also, not all of them are important and and of course Average Transaction Response time is usually the graph your client always want to see.

Below are few types of graphs that you should know that exists in Loadrunner. I have explained which are important.

Running Vusers Graph
This graph would give the number of Virtual users that were incremented during the course of the load test.

Vuser Summary Graph
Lets you view the number of Vusers that successfully completed the load test scenario run relative to those that did not. Lets you view the number of Vusers that successfully completed the load test scenario run relative to those that did not

Rendezvous Graph
It indicate when vuser were released from rendezvous point and how many vuser are released from each point.it help the transaction performance time

Error Statistics Graph
This graph displays the number of errors that occurred during load test scenario execution, grouped by error code.

Error Statistics (by Description) Graph
This graph displays the number of errors that occurred during load test scenario execution, grouped by error description. The error description is displayed in the legend.This graph can only be viewed as a pie.

Total Errors per Second Graph
This graph displays the average number of errors that occurred during each second of the load test scenario run.

Errors per Second Graph
This graph displays the average number of errors that occurred during each second of the load test scenario run, grouped by error code.

Errors per Second (by Description) Graph 

This graph displays the average number of errors that occurred during each second of the load test scenario run, grouped by error description. The error description is displayed in the legend.

Average Transaction Response Time Graph

This graph gives the average transaction response time for all transactions executed by all users. This is a good graph to get an indication of how the application is performing. There can be a spike during the beginning of the load test in terms of response time, because initially the application needs time to scale its resources as per the load. But you should then start to see a gradual decrease and stabilization of the transaction response time. If you don’t then this can be an indication that there is an issue with the application.

Transactions per Second Graph

This graph displays, for each transaction, the number of times it passed, failed, and stopped during each second of a load test scenario run.

Transaction Summary Graph

This chart is good in understanding the ratio of passed to failed transactions. The green bar represents the number of passed transactions and the orange one the number of failed transactions. So if you see a larger number of failed transactions, this would give an indication. You can further Drilled Down Transaction Summary by doing right click and choosing Drill option.

Transaction Performance Summary Graph

This gives a summary of the minimum, average and maximum time of transactions in the load test.

The graph will then be displayed as shown below when you add this to the Analysis session.

Transaction Response Time (Under Load) Graph

This graph is a combination of the Running Vusers and Average Transaction Response Time graphs and indicates transaction times relative to the number of Vusers running at any given point during the load test scenario.

Transaction Response Time (Percentile) Graph

This graph helps you understand whether your response time meet the accepted criteria.

The graph will then be displayed as shown below when you add this to the Analysis session.

Transaction Response Time (Distribution) Graph
This graph displays the distribution of the time taken to perform transactions in a load test scenario

Hits per Second Graph

This graph would provide the number of hits by the load test against the application. This graph is good to see if the load test was consistent in hitting the application with requests at the right intervals.

Throughput Graph

This graph would provide the number of bytes that was received by the Web server. This graph gives a good indication of the throughput of the application. If the throughput decreases as the user load increases then that can signal an issue in the application.

HTTP Status Code Summary Graph

This graph shows the number of HTTP status codes returned from the Web server during the load test scenario run, grouped by status code. HTTP status codes indicate the status of HTTP requests, for example, "the request was successful","the page was not found".This graph can only be viewed as a pie.

HTTP Responses per Second Graph

If you want to see the HTTP Responses per second, you need to go to the Summary Screen and click the ‘HTTP 200’ link in the HTTP Response Summary section. The HTTP Responses should be consistent throughout the load test. If the responses starts to decrease even though the number of users is high, that would indicate that there is an issue with the application.

Pages Downloaded per Second Graph

This graph shows the number of Web pages downloaded from the server during each second of the load test scenario run.

Retries per Second Graph

This graph displays the number of attempted server connections during each second of the load test scenario run.

Retries Summary Graph

This graph shows the number of attempted server connections during the load test scenario run, grouped by the cause of the retry.

Connections Graph

This graph gives the number of connections during the elapsed time of the load test. Obviously during the beginning of the load test, it should increase and decrease towards the end of the load test.

The graph will then be displayed as shown below when you add this to the Analysis session.

Connections per Second Graph

This graph gives the number of new connections and the number of connections which were shut down during the course of the load test.

The graph will then be displayed as shown below when you add this to the Analysis session.

Page Component Breakdown Graph

This is a useful graph for finding any response time issues per page. In this the response time for each page over the duration of the load test is provided.

The graph will then be displayed as shown below when you add this to the Analysis session.

Page Component Breakdown (Over Time) Graph

This graph displays the average response time (in seconds) for each Web page and its components during each second of the load test scenario run.

Page Download Time Breakdown (Over Time) Graph

This graph gives the time each page took to download from the server. If the time is high, then this is a cause of concern for the application.

Time to First Buffer Breakdown (Over Time) Graph

This graph displays each Web page component's relative server/network time (in seconds) for the period of time until the first buffer is successfully received back from the Web server.

Downloaded Component Size Graph
This graph displays the size of each Web page component.

Windows Resources Graph

This graph shows the Windows resources measured during the load test scenario. The Windows measurements correspond to the built-in counters available from the Windows Performance Monitor.

UNIX Resources Graph

The UNIX Resources monitor shows the UNIX resources measured during the test run. This graph helps you determine the impact of Vuser load on the various system resources.

SiteScope Graph

The SiteScope Resources monitor graph shows the SiteScope resources measured during the test run. The SiteScope monitor can measure server, network, and processor performance counters.

Merging graphs

Merging graphs can be useful when you want to view the information in 2 graphs at the same time. This can be useful for comparing results. Ensure that when you are merging graphs that at least one graph is open.

Let’s choose the Hits per second graph and then choose the Merge Graphs option from the Context menu.Then choose the option to merge the graph with the Running VUsers and then click the OK button.You will then get the complete picture of the number of hits per second as per the virtual users. The sample result is shown below.

Merging Types Overview
Overlay:
Superimpose the contents of two graphs that share a common x- axis. The left y-axis on the merged graph shows the current graph's values. The right y-axis shows the values of the graph that was merged. There is no limit to the number of graphs that you can overlay. When you overlay two graphs, the y-axis for each graph is displayed separately to the right and left of the graph. When you overlay more than two graphs, Analysis displays a single y-axis, scaling the different measurements accordingly.

Tile:
View contents of two graphs that share a common x-axis in a tiled layout, one above the other

Correlate:
Plot the y-axis of two graphs against each other. The active graph's y-axis becomes the x-axis of the merged graph. The y-axis of the graph that was merged, becomes the merged graph's y-axis.