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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". 
filesystemio_options=asynch
This parameter is platform specific. By default, this parameter is set to none for Linux and thus needs to be changed: 
SQL> show parameter filesystemio_options;

NAME                                 TYPE        VALUE
------------------------------------ ----------- -----------
filesystemio_options                 string      none
SQL>
The filesystemio_options can have the following values with Oracle 9i R2:
  • asynch: This value enables asynchronous I/O on file system files.
  • directio: This value enables direct I/O on file system files.
  • setall: This value enables both asynchronous and direct I/O on file system files.
  • none: This value disables both asynchronous and direct I/O on file system files.
If you also want to enable Direct I/O Support which is available in Red Hat Enterprise Linux 4 or 5, set filesystemio_options to "setall".

Important

In Red Hat Enterprise Linux 3, it is recommended you use direct I/O only for ext2, ext3, GFS, NFS and OCFS file systems.

Important

In Red Hat Enterprise Linux 4 and 5, it is strongly recommended to use the “setall” parameter for ext2, ext3, GFS, NFS and OCFS file systems.