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Chapter 12. Enabling Asynchronous I/O and Direct I/O Support
12.2. Relinking Oracle 10g to Enable Asynchronous I/O
Support
Ensure that for 10g Release 1 and 2 the libaio and libaio-devel RPMs are installed on the
system:
# rpm -q libaio libaio-devel
libaio-0.3.96-5
libaio-devel-0.3.96-5
If you relink Oracle for asynchronous I/O without installing the libaio RPM, then you will get an error
message similar to this one:
SQL> connect / as sysdba
oracleorcl: error while loading shared libraries: libaio.so.1: cannot open \
shared object file: No such file or directory
ERROR:
ORA-12547: TNS:lost contact
The libaio RPMs provide a native Linux asynchronous I/O API. In other words this is a kernel
accelerated asynchronous I/O for the POSIX asynchronous I/O facility.
Note
10g Release 2 is shipped with asynchronous I/O support enabled. This means that 10g
Release 2 does not need to be relinked. However, there is a bug in Oracle 10.1.0.2
that causes asynchronous I/O not to be installed correctly which can result in poor DB
performance, see Bug:3438751 and Note:270213.1.
To relink Oracle 10g R1 for asynchronous I/O, execute the following commands:
# shutdown Oracle
SQL> shutdown
su - oracle
$ cd $ORACLE_HOME/rdbms/lib
$ make PL_ORALIBS=-laio -f ins_rdbms.mk async_on
If asynchronous I/O needs to be disabled, run the following commands:
# shutdown Oracle
SQL> shutdown
su - oracle
$ cd $ORACLE_HOME/rdbms/lib
$ make -f ins_rdbms.mk async_off
12.3. Enabling Asynchronous I/O in Oracle 9i and 10g
If you use file systems instead of raw devices or ASM for data files, then you need to ensure that the
data files reside on file systems that support asynchronous I/O (OCFS/OCFS2, ext2 and ext3). To
do asynchronous I/O on file systems the filesystemio_options parameter needs to be set to
"asynch".
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