Symptom
Clients experience issues accessing Web service.
Solution
Do not block ports 80 or 16080 when setting up the IP Filtering feature of Mac OS X Server or any router or firewall.
Performance Cache communicates on port 80, which is normally used for Web service. Each port can accommodate only one service. Since the Performance Cache process is a front end http server by itself, Apache is reconfigured to run on port 16080. Performance Cache is enabled by default.
Interaction between Performance Cache and Apache
The Performance Cache stores data that can be reserved to clients who request it again. However, not all data can be cached. In this case, Performance Cache retrieves the data by querying Apache locally on port 16080. You may sometimes see clients sending requests to port 16080 directly, as the result of a redirect sent to the clients by Apache. Otherwise the Performance Cache process should transmit all request-response cycles.
Note: Because of this design, the Performance Cache process introduces a small performance penalty when serving dynamic content.
How to enable or disable Performance Cache
Click to select/deselect the checkbox for "Enable performance cache" in the Server Admin application. This setting is located in the General pane of the Web Service module of Server Admin.
In Server Settings, click the Sites tab in the Configure Web Service window. Double-click the site name, then click the Options tab in the resulting window (which will be named after the site you opened).