hai friends,
   can any one tell what is ha manager in was?use of it?how to enable? 

HA Manager basically ensures availability of singleton services with WAS, in the event of an failure or unavailability of those services.

Sigleton services  in WAS are 1. Transaction service 2. Messaging Engine Services.

HA Mgr service runs within each application server & it immediately fails over to the next cluster member to ensure the in-flight transactions or the messaging engine related acitivities are not affected.

thank you sree for your reply but i what is singleton ?can you give some more information about ha manager.

saravana,

  Singleton service is a service that can run in diferents servers but only in one at the time.

  If you deploy an application in a cluster all member of the cluster can execute it.  In singleton pattern only one of the cluster members execute the service, if this member fails or is stoped the service is switch to other member automatically.

  You can get information about the WebSphere HA Manager in

  WebSphere Application Server Network Deployment V6: High Availability Solutions  publib-b.boulder.ibm.com/abstracts/sg246...

  Chapter 6.

  Or 

  WebSphere Application Server V6 Scalability and Performance Handbook

  publib-b.boulder.ibm.com/abstracts/sg246...

  Chapter 9.

 Hope this helps

regards

Thank you Gabriel.