Testing the ZDS

The Test ZDS tab is accessed from Performance | Testing | Test Download.

Once the ZDS has been configured a test can be run to check and analyze the overall efficiency.

The default ZDS test uses the Manual mode of operation to invoke a PHP script, which sends a file of approximately 300KB.
The same test tool can be used to check the 'Transparent' mode. Make sure that you correctly map the file type you are checking in your Web server's configuration file - according to the configuration instructions.

The test simulates multiple requests for a specified URL, with and without ZDS. There are three sets of tests; each test is performed twice (once with the ZDS disabled and once with the ZDS enabled). These tests differ in the number of concurrent clients that simultaneously perform requests to the server.

Note:

It is extremely hard to artificially test ZDS. The main reason is that testing it on a LAN can easily saturate your local network, and if your MaxClients is very high, Apache Benchmark (ab) may have difficulty handling the concurrency. For this reason, it is recommended to test ZDS with a relatively low MaxClients setting (e.g., 50-150) so that you don't reach any of these limits. The ZDS includes a version of ab, which was modified to support bandwidth throttling, which is used by the testing tool.

Caution:

During a test, your Web server will be fully loaded. A test can take several minutes so you should run it on a development machine or on an offline production machine.

To Test the ZDS:

Go to Performance | Testing and go to the Test Download tab.

Performance - Testing - Test Download Tab

The Test Download Tab consists of two sections: The test options are on the upper section and the test results appear below (after running a test or displaying the last test results).

Running a Test


	Type in the URL you want to test. The default test is a PHP script which uses zend_send_file() to send a 300K zip file (Testing very large files will take a very long time). Choose the bandwidth limit you want to simulate for the clients. For a faster test, select a higher bandwidth (You cannot choose full bandwidth because your network card will be saturated, making the test irrelevant. The test tries to simulate a typical Internet server that has clients connected either by ISDN or DSL). Enter the number of maximum clients that your server can handle. Use the precise value by checking the value of the MaxClients directive in your server’s configuration file (The ZDS tries to identify your MaxClients value in the installation process, via the httpd.conf file, which is the default value. However, this value can be changed after the installation; and should be double-checked. Using an inaccurate MaxClients value, may not present accurate results). Click Run.

Related Links:
Test Download

Understanding Test Results