10gR2 for linux has the executable already linked for async I/O. It is not possibile to relink against different libaio anymore. You shouldn't try the async_on/async_off on this version. Regards Fabrizio Has anyone successfully relinked Oracle 10.2.0 on RHEL 4 with async i/o on? According to notes I've found, you need to do the following: cd $ORACLE_HOME/rdbms/lib make PL_ORALIBS=-laio -f ins_rdbms.mk async_on