MDB_MODULE and the GWEJB ear are deployed in a cluster. Cluster has 4 managed servers, if any server goes down then the messages are processed by other managed servers.
JMS Provider:
JMS is deployed on 2 managed servers, JMSServer1 and JMSServer2, if any one goes down other will handle the messages.
FileStore:
File store is a cluster file system or database where if one node goes down then other will handle the requests.
DB Server:
Database is installed in RAC mode where it has more than 1 node, if a node goes down then other nodes will handle messages.