Fast Response Cache Accelerator operational restrictions

This section discusses the operational restrictions for the fast response cache accelerator (FRCA). FRCA is also known as Adaptive Fast Path Architecture (AFPA).

The following operational restrictions apply:
  • When FRCA is enabled, the default value of 0 for the MaxRequestsPerChild directive should be used, because graceful server restart is not supported with the cache accelerator.
  • FRCA does not support Windows 64-bit operating systems.
  • FRCA cannot be used when certain antivirus software is enabled. Currently Norton Antivirus has been identified as one such program.
  • FRCA access log entries are not integrated with the Apache access log.
  • Only access logging facilities exist for monitoring FRCA.
  • On a given machine, only one instance of the IBM® HTTP Server can have FRCA enabled.
  • Do not install the IBM HTTP Server on a machine running the IBM Netfinity Web Server Accelerator.
  • FRCA does not support IPv6.
  • FRCA must not be used with locally-mounted network file systems, such as Network File System (NFS) or Windows shared drives.
  • On Windows systems, AFPA cannot be loaded if using the Win32DisableAcceptEx directive
  • FRCA is not supported on Windows Vista, Windows 2008, or any later Windows operating systems.
  • FRCA on AIX® is only supported with the 32-bit installation of IBM HTTP Server.

Due to these operational restrictions, and since FRCA/AFPA was deprecated starting in V7.0, its use is discouraged. Instead, it is recommended to use the IBM HTTP Server default configuration to serve static files. This configuration provides support for features not available with FRCA/AFPA usage, such as IPv6, SSL, Authentication and access-control, custom headers and compression.

If CPU usage with the default configuration is too high, the mod_mem_cache module can be configured to cache frequently accessed files in memory, or multiple web servers can be used to scale out horizontally. Additional options include the offloading of static files to a Content Delivery Network (CDN) or caching HTTP appliance, or to use the caching proxy component of WebSphere® Edge Server in WebSphere Application Server Network Deployment (ND).