关于asm上使用filesystemio_options初始化参数的问题
关于asm上使用filesystemio_options初始化参数的问题。
昨天有个哥们问我，他的数据库是linux x86-64bit下的rac（使用asm），设置filesystemio_options初始化参数能提高数据库性能么？
我查了一下mos文章，Things To Consider For Setting filesystemio_options And disk_asynch_io (文档 ID 1987437.1)
在该文章中的“File System–specific Notes”部分,有如下论述
File System–specific Notes
| File System | Notes |
|---|---|
| Raw device |
Raw device access to disks does not involve a file system. The filesystemio_options parameters is always ignored and direct I/O is always used. Under Linux, block devices are also treated this way. Direct use of raw or block devices is not supported as of 12c. |
| ACFS |
ACFS is not supported for database files that can be stored directly in ASM, including data files, redo files, and control files, but there is an exception for Linux Exadata. SeeDocument 1929629.1 and Document 1369107.1. |
| ASM---->此处 | Oracle bypasses the file system layer for ASM. Thefilesystemio_options parameters is always ignored and direct I/O is always used. SeeDocument 751463.1 for more.---->此处 |
| FUSE (Linux) |
Direct I/O cannot be enabled on FUSE-based file systems. |
| JFS (IBM) |
Not to be confused with JFS or OnlineJFS on HP-UX, which is VxFS as supplied with HP-UX. JFS comes in two versions. Version 1 of JFS (JFS1) is available on AIX only. Version 2 of JFS (JFS2) is available on several OSes, and is usually called "JFS" on operating systems other than AIX. JFS1 does not support concurrent I/O, but JFS2 does. |
| NFS |
Using direct I/O is recommended to avoid potential data corruption. See Document 437005.1 for more. Whether concurrent I/O is used is controlled by the NFS server. |
| Direct NFS (dNFS) | Oracle bypasses the file system layer when using Direct NFS. The filesystemio_options parameters is always ignored and direct I/O is always used. |
| VxFS/JFS/OnlineJFS (Veritas) |
VxFS as supplied with HP-UX is known as JFS or OnlineJFS; not to be confused with IBM JFS. Direct I/O cannot be set using filesystemio_options on platforms other than HP-UX. Instead, use the convosync=direct and mincache=direct mount options to force direct I/O or the cio option to force concurrent I/O. Concurrent I/O is an extra option on VxFS (called "Concurrent I/O"). It is also available through the Quick IO option or ODM. Otherwise concurrency will be limited. NB: ODM is the preferred method of accessing Oracle files on VxFS. |
| VxFS ODM | Oracle bypasses the file system layer when using ODM on VxFS. The filesystemio_options parameters is always ignored and direct I/O is always used. Asynchronous I/O is supported natively by the ODM interface. |
| ZFS |
ZFS does not support direct I/O and consequently cannot be used with RAC. With ZFS you can limit how much RAM the ARC consumes in certain Solaris releases. SeeDocument 1663862.1. |
额外说一个很严重的bug：
ORA-1578 ORA-353 ORA-19599 Corrupt blocks with zeros when filesystemio_options=SETALL on ext4 file system using Linux (Doc ID 1487957.1)