PH46938: IBM WEBSPHERE APPLICATION SERVER WEBSERVER PLUGIN MAY NOT FORWARD REQUEST

APAR status

• Closed as new function.

Error description

• When the webserver plugin has marked all servers in a
  server group down, requests mapped to this server group will
  not be forwarded. Plugin will forward a request if the
  RetryInterval for a marked down server has expired. A
  request is not forwarded when all servers are marked down and
  it is not time to retry any of the servers.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  IBM WebSphere Application Server web        *
  *                  server plugin users                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: When all servers in a cluster are       *
  *                      marked as offline, the web server       *
  *                      plugin does not attempt to forward      *
  *                      requests.                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The WebSphere web server plugin forwards requests from the web
  server to the Application server. When an application server
  fails to respond as expected, plugin marks the application
  server down and stops forwarding requests to that application
  server. Plugin will attempt to forward requests to the
  application server again after the plugin RetryInterval
  expires. Conditions can occur such that all servers in a
  cluster are marked offline. If this occurs, plugin does not
  attempt to forward the request and the client receives
  a "500 Internal Server Error" response.
  The web server plugin can be configured with backup servers
  for a cluster. When backup servers are defined, when all
  primary servers are marked offline, plugin routes the request
  to a backup server. If all primary servers and all backup
  servers are offline, plugin does not attempt to forward the
  request and the client receives a "500 Internal Server Error"
  response.
  

Problem conclusion

• Code has been modified such that when plugin detects that all
  servers are offline in a particular cluster, plugin will set
  the internal status of all servers to online and attempt to
  route requests to the servers. If a server fails to respond as
  expected, it will be marked offline again. When primary
  servers and backup servers are defined, plugin will mark all
  the primary servers online when both all the primary and all
  the backup servers are offline. By marking the servers up in
  this situation, there is a chance that at least one of the
  servers has recovered and can respond to the client's request.
  
  Note that a request will fail and the client receives a 500
  response on the request in which the last server in the
  cluster is marked down. The servers are marked up after the
  request has attempted all available servers and the request
  will not be retried after the servers are marked up.
  
  This code modification does not affect Plugin users with the
  Intelligent Managment feature enabled.
  
  Plugin's server status check which occurs after the
  RetryInterval expires is not affected and continues to
  function as described in original documentation.
  
  Additional plugin information regarding server status and
  backup servers is available:
  https://www.ibm.com/support/pages/understanding-ibm-web-server-p
  lug-failover-clustered-environment
  
  The fix for this APAR is targeted for inclusion in fix pack
  8.5.5.23 and 9.0.5.13. For more information, see 'Recommended
  Updates for WebSphere Application Server':
  https://www.ibm.com/support/pages/node/715553
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  WEBSPHERE APP S

• Fixed component ID

  5724J0800

Applicable component levels