1. 參數說明

You can use the FILESYSTEMIO_OPTIONS initialization parameter to enable or disable asynchronous I/O or direct I/O on file system files. This parameter is platform-specific and has a default value that is best for a particular platform.

FILESYTEMIO_OPTIONS can be set to one of the following values:

ASYNCH: enable asynchronous I/O on file system files, which has no timing requirement for transmission.

DIRECTIO: enable direct I/O on file system files, which bypasses the buffer cache.

SETALL: enable both asynchronous and direct I/O on file system files.

NONE: disable both asynchronous and direct I/O on file system files.

2. 修改參數

SQL> show parameter filesystemio

NAME TYPE VALUE

------------------------------------ ----------- ------------------------------

filesystemio_options string none

SQL>

SQL> alter system set filesystemio_options=setall ;

alter system set filesystemio_options=setall

*

ERROR at line 1:

ORA-02095: specified initialization parameter cannot be modified

#文件系統如果出現io問題，建議設置為setall

SQL> alter system set filesystemio_options=setall scope=spfile;

System altered.

SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup

ORACLE instance started.

Total System Global Area 784998400 bytes

Fixed Size 2217464 bytes

Variable Size 473958920 bytes

Database Buffers 306184192 bytes

Redo Buffers 2637824 bytes

Database mounted.

Database opened.

SQL> show parameter filesystemio_options

NAME TYPE VALUE

------------------------------------ ----------- ------------------------------

filesystemio_options string SETALL

SQL>

3. 官方鏈接

https://docs.oracle.com/cd/E11882_01/server.112/e41573/os.htm#PFGRF94413

FILESYSTEMIO_OPTIONS-性能優化參數