Chapter 12. Enabling Asynchronous I/O and Direct I/O Support3212.2. Relinking Oracle 10g to Enable Asynchronous I/OSupportEnsure that for 10g Release 1 and 2 the libaio and libaio-devel RPMs are installed on thesystem:# rpm -q libaio libaio-devellibaio-0.3.96-5libaio-devel-0.3.96-5If you relink Oracle for asynchronous I/O without installing the libaio RPM, then you will get an errormessage similar to this one:SQL> connect / as sysdbaoracleorcl: error while loading shared libraries: libaio.so.1: cannot open \shared object file: No such file or directoryERROR:ORA-12547: TNS:lost contactThe libaio RPMs provide a native Linux asynchronous I/O API. In other words this is a kernelaccelerated asynchronous I/O for the POSIX asynchronous I/O facility.Note10g Release 2 is shipped with asynchronous I/O support enabled. This means that 10gRelease 2 does not need to be relinked. However, there is a bug in Oracle 10.1.0.2that causes asynchronous I/O not to be installed correctly which can result in poor DBperformance, see Bug:3438751 and Note:270213.1.To relink Oracle 10g R1 for asynchronous I/O, execute the following commands:# shutdown OracleSQL> shutdownsu - oracle$ cd $ORACLE_HOME/rdbms/lib$ make PL_ORALIBS=-laio -f ins_rdbms.mk async_onIf asynchronous I/O needs to be disabled, run the following commands:# shutdown OracleSQL> shutdownsu - oracle$ cd $ORACLE_HOME/rdbms/lib$ make -f ins_rdbms.mk async_off12.3. Enabling Asynchronous I/O in Oracle 9i and 10gIf you use file systems instead of raw devices or ASM for data files, then you need to ensure that thedata files reside on file systems that support asynchronous I/O (OCFS/OCFS2, ext2 and ext3). Todo asynchronous I/O on file systems the filesystemio_options parameter needs to be set to"asynch".
