Hi, I am using JBoss Cache in a cluster environment. 1. get some X from the cache 2. update X (for example, X++) 3. put the updated X back to the cache 4. return X to the client What I see is when this code is called repeatedly and simultenously from different PCs, the returned X is sometimes the same as the one on another PC! The code is being called from a stateless session bean. Playing with TransactionAttribute I sometimes got org.jboss.cache.lock.UpgradeException, sometimes the situation described above. Here is some of the cache settings: <attribute name="TransactionManagerLookupClass">org.jboss.cache.JBossTransactionManagerLookup</attribute> | <attribute name="IsolationLevel">SERIALIZABLE</attribute> | <attribute name="NodeLockingScheme">PESSIMISTIC</attribute> | <attribute name="CacheMode">REPL_SYNC</attribute> | How should I achieve data integrity using TreeCache? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4007542#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...