Chapter 12.31Enabling Asynchronous I/O and DirectI/O SupportAsynchronous I/O permits Oracle to continue processing after issuing I/Os requests which leads tohigher I/O performance. Red Hat Enterprise Linux also allows Oracle to issue multiple simultaneousI/O requests with a single system call. This reduces context switch overhead and allows the kernel tooptimize disk activity.To enable asynchronous I/O in Oracle Database, it is necessary to relink Oracle 9i and 10g Release 1.Note10g Release 2 is shipped with asynchronous I/O support enabled and does not need to berelinked. But you may have to apply a patch, see below.12.1. Relinking Oracle9i R2 to Enable Asynchronous I/OSupportNoteOracle 9iR2 on Red Hat Enterprise Linux 3, 4 and 5 the 9.2.0.4 patchset or higherneeds to be installed together with another patch for asynchronous I/O, see MetalinkNote:279069.1.To relink Oracle9i R2 for asynchronous I/O, execute the following commands:# shutdown OracleSQL> shutdownsu - oracle$ cd $ORACLE_HOME/rdbms/lib$ make -f ins_rdbms.mk async_on$ make -f ins_rdbms.mk ioracle# The last step creates a new "oracle" executable "$ORACLE_HOME/bin/oracle".# It backs up the old oracle executable to $ORACLE_HOME/bin/oracleO,# it sets the correct privileges for the new Oracle executable "oracle",# and moves the new executable "oracle" into the $ORACLE_HOME/bin directory.If asynchronous I/O needs to be disabled, execute the following commands:# shutdown OracleSQL> shutdownsu - oracle$ cd $ORACLE_HOME/rdbms/lib$ make -f ins_rdbms.mk async_off$ make -f ins_rdbms.mk ioracle
