Veritas Storage Foundation 5.1 SP1 Cluster File System Administrator"s Guide (5900-1738, April 2011)

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Restart the database instance.
Using Cached ODM
ODM I/O normally bypasses the file system cache and directly reads from and
writes to disk. Cached ODM enables some I/O to use caching and read ahead, which
can improve ODM I/O performance. Cached ODM performs a conditional form of
caching that is based on per-I/O hints from Oracle. The hints indicate what Oracle
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 137.
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 138.
See “Adding Cached ODM settings via the cachemap” on page 139.
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.
137Using Veritas Extension for Oracle Disk Manager
Using Cached ODM