Fix (APAR):  PQ98295

Status:  Fix

Release:  5.0.2.8

Operating System:  All

Supersedes Fixes:  

CMVC Defect:  PQ98295

Byte size of APAR:  50863

Date: 2004-12-10

Abstract:  Improve Dynamic Cache disk offload JVM memory utilization.

Description/symptom of problem:  During high disk offload demand, the high rate
of allocation / deallocation of resources might
cause the JVM heap to become unusally fragmented. 
The high allocation / deallocation rate could also
overwhelm the JVM GC handler.
In rare cases, this could result in a permanent 
memory allocation failure.  

This APAR will do the following:
  - Reduce the JVM memory requirements for 
    the disk offload function.
  - Reduce the JVM memory allocation / deallocation
    cycles from the disk offload classes.
  - Reduces disk offload initial file system
    requirements by 80%. 

Important:  This APAR changes the disk offload
            file format.  You must manually delete
            the disk offload files from your
            system.  The default location
            for these files is:
              [install_root]/AppServer/temp
              /[node_name]/[server_name]/_dynacache
            You must delete all files and
            sub-directories under the _dynacache
            directory.






Directions to apply fix:  

NOTE:  YOU MUST FIRST DOWNLOAD THE UPDATE INSTALLER TOOL IN ORDER TO INSTALL A FIX.
       The Fix Installer can be downloaded from the following link:
       http://www-3.ibm.com/software/webservers/appserv/support/index.html

1) Create temporary "fix" directory to store the jar file:
             UNIX: /tmp/WebSphere/fix
          Windows: c:\temp\WebSphere\fix

2) Copy jar file to the directory

3) Shutdown WebSphere

4) Follow the Fix installation instructions that are packaged with the Fix Installer on how to install the Fix.

5) Deleted the disk offfload files and
   the temp directory may also be removed.

6) Restart WebSphere






Directions to remove fix:  
NOTE:  FIXES MUST BE REMOVED IN THE ORDER THEY WERE APPLIED.  DO NOT REMOVE A FIX UNLESS
     ALL FIXES APPLIED AFTER IT HAVE FIRST BEEN REMOVED.  YOU MAY REAPPLY ANY REMOVED FIX.

Example:  If your system has fix1, fix2, and fix3 applied in that order and fix2 is to be
          removed, fix3 must be removed first, fix2 removed, and fix3 re-applied.


1) Shutdown WebSphere

2) Follow the instructions that are packaged with the Fix Installer on how to uninstall the Fix.

3) Restart WebSphere





Directions to re-apply fix:  
1) Shutdown WebSphere

2) Follow the Fix instructions that are packaged with the Fix Installer on how to uninstall and reinstall the Fix.

3) Restart WebSphere







Additional Information: