Monday, August 13, 2018

EBS -- MIGRATION // 2 interesting problems & 2 facts -- autoconfig rule (2n-1) & APPL_SERVER_ID in the plan.xml of ebsauth

Recently migrated a production EBS from an Exadata to another Exadata. That was an advanced operation, as it involved Oracle Access Manager(OAM), Oracle Internet Directory(OID) and 2 EBS disaster environments.,

This was a very critical operation, because it was not tested.. Moreover; we needed to do this work without any tests and we needed start working immediately..

The environment was as follows;

PROD : 1 Load Balancer, 2 Apps Nodes, 1 OAM/OID node and 2 Database nodes (Exadata)
-- Parallel Concurrent Processing involved as well..
Local Standby : 1 Apps Node, 2 Database nodes (Exadata)
Remote Standby: 1 Apps Nodes, 2 Database nodes (Exadata)

What we needed to do was; migrating the DB nodes of PROD, to Local Standby.
In order to do this; we followed the action plan below;

Note: actually we did much more than this, but this action plan should give you the idea :) 
  • stopped OAM+OID+EBSAccessGate + Webgate etc..
  • stopped EBS apps services which were running on both of the Prod Apps nodes.
  • Switched over the EBS Prod database to be primary in Local Standby.
  • Reconfigured local standby to be the new primary and configured it as the primary for the remote standby as well.
  • After switching the database over the standby site; we cleaned up the apps specific conf which was stored in the database (fnd_conc_clone.setup_clean)
  • We built context files ( and executed autoconfig on the new db nodes. 
  • Once db nodes were configured properly; we manually edited the apps tier context files and executed autoconfig on each of the apps tier nodes. (note that ; apps services were not migrated to any other servers)
  • We started the apps tier services.
  • We reconfigured the workflow mailer (its configuration was overwritten by autoconfig)
  • We logged in locally (without OAM) , checked the OAF , Forms and concurrent managers.
  • Everything was running except the concurrent manager which were configured to run in the second apps node. No matter what we did from the command line and from the concurrent manager administration screens, we couldn't fix it.. There was nothing written in the internal manager log, but the concurrent managers of node 2 could not be started.. 
    • The first fact : If you have a multi node EBS apps tier, AutoConfig has to be run '2n - 1' times. In other words;   for an application which has 'n' number of application nodes, AutoConfig has to be run '2n - 1' times so that the tnsnames.ora file on each node has FNDSM entries for all the other nodes. So, as for the solution, we executed autoconfig once more in the second node, and the problem dissapeared.
Reference: AutoConfig Does Not Populate tnsnames.ora With FNDSM Entries For All The Nodes In A Multi-Node Environment (Doc ID 1358073.1)
  • After fixing the conc managers, we continued with the OAM and OID.. We changed the datasource of the SSO (in weblogic) with the new db url and also changed dbc file there.. Then, we started Access Gate, Webgate, OAM and OID and checked the EBS login by using SSO-enabled url. But, the login was throwing http 404..
  • All the components of SSO (OAM,OID and everyting) was running.. But only the deployment named ebsauth_prod was stopped and it could not be started ( it was getting errors)
    • The second fact : if you changed the host of the EBS database and if your APPL_SERVER_ID was changed, then you need to redeploy the ebsauth by modifying it Plan.xml with the new APPL_SERVER_ID. Actually you have 2 choices; 1) Set the app_APPL_SERVER_ID to a valid value in the Plan.xml file for the AccessGate deployment and then restart the EAG Servers. The Plan.xml file location is specified on the Overview Tab for the AccessGate Deployment within the Weblogic Console where AccessGate is deployed. 2) Undeploy and redeploy AccessGate. 
Reference: EBS Users Unable To Sign In using SSO After Upgrading To EBSAccessGate 1234 With OAM 11GR2PS2 (Doc ID 2013855.1)
  • Well. after this move, SSO-enabled EBS login started to work as well. The operation was completed , and we deserved a good night sleep :)

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