Veritas File System 5.1 SP1 Administrator"s Guide (5900-1499, April 2011)

does with the data. ODM uses these hints to perform caching and read ahead for

some reads, but ODM avoids caching other reads, even for the same file.

You can enable cached ODM for local mount files and cluster mount files.

See “Enabling Cached ODM for file systems” on page 118.

Cached ODM can be configured in two ways. The primary configuration method

is to turn caching on or off for all I/O on a per-file basis. The secondary

configuration method is to adjust the ODM cachemap. The cachemap maps file

type and I/O type combinations into caching advisories.

See “Modifying Cached ODM settings for individual files” on page 118.

See “Adding Cached ODM settings via the cachemap” on page 119.

Enabling Cached ODM for file systems

Cached ODM is initially disabled on a file system. You enable Cached ODM for a

file system by setting the odm_cache_enable option of the vxtunefs command

after the file system is mounted.

See the vxtunefs(1M) manual page.

Note: The vxtunefs command enables conditional caching for all of the ODM files

on the file system.

To enable Cached ODM for a file system

Enable Cached ODM on the VxFS file system /database01:

# vxtunefs -s -o odm_cache_enable=1 /database01

Optionally, you can make this setting persistent across mounts by adding a

file system entry in the file /etc/vx/tunefstab:

/dev/vx/dsk/datadg/database01 odm_cache_enable=1

See the tunefstab(4) manual page.

Modifying Cached ODM settings for individual files

You can use the odmadm setcachefile command to override the cachemap for a

specific file so that ODM caches either all or none of the I/O to the file. The caching

state can be ON, OFF, or DEF (default). The DEF caching state is conditional

caching, meaning that for each I/O, ODM consults the cachemap and determines

whether the specified file type and I/O type combination should be cached. The

Using Veritas Extension for Oracle Disk Manager

Using Cached ODM

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