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Problem(Abstract) |
A useful debugging tip that occasionally resolves Web
server performance problems is to disable AFPA (fast cache) in IBM HTTP
Server. Because only sites that receive very high volumes (millions of
hits a day) notice significant performance impact, this action does not
interfere with normal operations. Note: This technote is only applicable
to 32-bit Windows operating systems. AFPA does not support Windows 64-bit
operating systems and therefore should never be enabled. |
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Resolving the
problem |
Perform the following steps to disable AFPA:
- Save a backup copy of the httpd.conf file located in the
install_root/conf directory.
- For IBM HTTP Server V1.3:
- Edit the original httpd.conf file and comment out
the following three AFPA lines (insert "#" in front of each line):
# AfpaEnable
# AfpaCache on
# AfpaLogFile "path/to/afpalog" V-ECLF |
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- Add a Listen 80 directive in the
httpd.conf file.
The Listen 80 directive is needed because port 80 only binds the
root process to the port. By default on Windows systems, IBM HTTP Server
listens on the AFPA socket and not the default Windows socket. Adding the
Listen 80 directive forces the Web server to listen on the
default Windows socket when AFPA is disabled.
For IBM HTTP Server V2.0 and V6.0:
- If there is no <IfModule mod_afpa_cache.c>
line in the httpd.conf file, follow the instructions for IBM HTTP
Server V1.3.
- If there is an <IfModule mod_afpa_cache.c>
line in the httpd.conf file, comment out the LoadModule for AFPA.
For example:
#LoadModule ibm_afpa_module
modules/mod_afpa_cache.so |
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- If there is a Listen @@Port@@ directive below the
<IfModule !mod_afpa_cache.c> (note the "!" symbol in this
line), then replace it with the following:
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- Stop IBM HTTP Server.
- Delete the file that is referenced by the AfpaLogFile
(referenced in step 2) file. The default naming convention of the log
files is afpalog.* (for example, afpalog.5Sep2001).
- Start IBM HTTP Server.
- Verify that IBM HTTP Server is started and that no new
afpalog.* file was created.
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