非同步IO

"Checked for relevance on 07-Feb-2007, archived"

PURPOSE
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To enable asynchronous I/O for Oracle9iR2 on Red Hat Linux Advanced Server
2.1, please execute the following steps:

1) cd to $ORACLE_HOME/rdbms/lib

   a) make -f ins_rdbms.mk async_on

   b) make -f ins_rdbms.mk ioracle


2) Parameter settings in init.ora for raw devices:

   a) set 'disk_asynch_io=true' (default value is true)


3) Parameter settings in init.ora for filesystem files:

   a) Make sure that all Oracle datafiles reside on filesystems that support
      asynchronous I/O. (For example, ext2)

   b) set 'disk_asynch_io=true' (note default value is true)

   c) set 'filesystemio_options=asynch'

4) Increase the size of sys.fs.aio-max-size using:

         echo >/proc/sys/fs/aio-max-size 1048576

   to get good performance.

If asynchronous I/O needs to be disabled for some reason

1) cd to $ORACLE_HOME/rdbms/lib

   a) make -f ins_rdbms.mk async_off

   b) make -f ins_rdbms.mk ioracle



Note : 
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A)Before relinking, please stop any processes running out of that 
ORACLE_HOME to ensure that none of those files are currently in use

B)By default, Oracle9iR2 is shipped with asynchronous I/O support disabled.




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