Configuring fast response cache accelerator cache size through a distributed platforms web server

In the default IBM® HTTP Server for distributed platforms configuration, the maximum fast cache accelerator dynamic cache size is calculated as one-eighth of physical pin-able memory.

About this task

On a machine with 384 megabytes of RAM, a maximum of approximately 50 megabytes is available for the fast response cache accelerator dynamic cache. When this limit is reached, the cache accelerator deletes older entries to cache new entries.

Procedure

Using the IBM HTTP Server for distributed platforms AfpaDynaCacheMax directive, tune the maximum-allowed cache size:

Place the directive in the global server configuration scope, along with the other default fast response cache accelerator directives.
Enable fast response cache accelerator.
Enable the fast cache accelerator by updating the following directives in the IBM HTTP Server httpd.conf file:
```
AfpaEnable
AfpaCache on
AfpaLogFile "c:/Program Files/IBM HTTP Server/logs/afpalog" V-ECLF
AfpaDynaCacheMax 10
```
These settings limit the dynamic cache size to 10 megabytes. If you use these directives to increase cache size, do not make the cache so large that all of the physical memory is consumed. Determine how much memory is available when all applications are running, by using the Windows Task Manager.

Assign no more than 50% of available physical memory to the dynamic cache. Specifying too large a cache not only decreases the performance of other applications, but also puts you at a risk for completely running out of memory.

The default configuration does not include the AfpaDynaCacheMax directive, where the cache size is automatically calculated as one eighth of physical memory.