Customizing Fast Response Cache Accelerator logging

The fast response cache accelerator (FRCA) can improve the performance of the IBM HTTP Server when serving static content, such as text and image files. By default, FRCA generates an access log of all requests that are served out of the cache. In order to minimize the effect of logging on performance, this is a separate file from the normal Apache access log.

 

Overview

When FRCA is enabled, the default configuration setting allows all static files to be cached. The cache automatically loads during server operation so that individual files do not need to be listed. Use the AfpaCache directive to turn caching on or off for specific directories.

FRCA will remove files from the cache when they change to avoid serving stale content.

Enable the FRCA access log if we want to maintain a record of requests served by FRCA. Requests that are not served out of the cache will be logged in the
FRCA access log file. The FRCA access log file provides a useful way to verify that caching is enabled and to identify cached files.

Even though a particular file might be cached, it might not always be served from the cache. Therefore, not every request for a cached file will result in an FRCA access log entry.

If we do not need access logging, turn the logging off for better performance.

 

Procedure

• To turn FRCA logging off, edit the httpd.conf configuration file.

  Configure AfpaLogging off.

  Insert a comment character (#) at the beginning of the AfpaLogFile line. For example:

  #AfpaLogFile "_path_to_server_/logs/afpalog" V-ECLF
  
  

• For each request that is served by the fast response cache accelerator, a log entry in the access log displays the following:

  • Source host address

  • Date and time of the request

  • HTTP method of the request and what is requested

  • HTTP return code, which indicates whether the request is honored

  • Size of the returned data

  A log entry can also optionally display the following:

  • Target virtual host (use the formatting option V-CLF or V-ECLF)

  • HTTP referer (use the formatting option V-CLF or V-ECLF)

  • HTTP user agent (use the formatting option V-CLF or V-ECLF)

  

  The log file has a date stamp that automatically appends to its name. Everyday at midnight the server closes the current access log and creates a new one. This action enables the log file to process without having to stop and restart the server. Under heavy load conditions the log file can grow rapidly. Provide sufficient space on the hard drive for storage.

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Related reference

AFPA directives