Microsoft Sharepoint Products and Technologies Resource Kit eBook

230 Part III: Planning and Deployment
You can see that the RPS of the portal site stops growing at around 22 RPS. The
other thing that is important to notice is that the latency increases as more load is
generated.
Generating Load and Interpretation of the Results
The purpose of stress testing is to determine how a portal site will perform and to
identify bottlenecks under load. Running scripts for the different scenarios that accurately
simulate the expected production traffic will generate load on the servers. The
purpose of a performance test should be to find out the maximum throughput under
load. To better understand what might be acting as the bottleneck of the portal site,
it makes sense to check for several counters on the different servers.
The most interesting point to find out is the throughput capabilities of the portal
site. Throughput is the amount of work that the portal site can do in a given time
period. In this case, that would mean finding out how many requests per second the
portal site can handle. Splitting the performance counters into three groups makes
sense. First of all, we have to make sure that the clients are not suffering too much
under the load they are generating. Second, using different counters for the SQL
server and the front-end servers will show us where the bottleneck lies (that is, at
the front end or back end).
All the different scripts can be run with the ACT test tool, and there will be two
kinds of results that can be analyzed. One type is the Web server responses that tell
you whether there were any HTTP errors, how many pages have been processed,
how long it took to open up the page, and so on. The other results are the performance
counters that also indicate server hardware-related results.
Types of Scripts
As defined earlier, the most basic script contains just one line:
Test.SendRequest(“http://sps”)
What this script does is send a request to the server http://sps and requests the
default page for the site. Because this is a corporate portal site, the default page is
Default.aspx. The Web server processes the Default.aspx page and returns the result
to the client computer. ACT times this whole transaction and uses that information
to generate RPS data. Running this script will generate performance data for your
server or server farm, but it is not particularly useful unless the only thing your users
do is go to the Home page of the corporate portal site.
Using a mixed-scenario script is much more useful for testing the portal site.
The following script performs the general workload mix on a specified corporate
portal site. This script can be modified for divisional portal sites or to include other
sites. It can also be modified for specific workload mix requirements of your organization.
The code for the mixed scenario script is as follows: