VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Enabling Cached Quick I/O on the File System Prerelease 8 September 2005, 8:54am
112 VERITAS Storage Foundation for Oracle Administrator’s Guide
Enabling Cached Quick I/O on the File System
Cached Quick I/O depends on VERITAS Quick I/O running as an underlying system enhancement
in order to function correctly. Follow the procedures listed here to ensure that you have the correct
setup to use Cached Quick I/O successfully.
Prerequisites
◆ You must have permission to change file system behavior using the vxtunefs command to
enable or disable Cached Quick I/O. By default, you need superuser (root) permissions to
run the vxtunefs command, but other system users do not. Superuser (root) must
specifically grant database administrators permission to use this command as follows:
# chown root:dba /sbin/fs/vxfs4.1/vxtunefs
# chmod 4550 /sbin/fs/vxfs4.1/vxtunefs
where users belonging to the dba group are granted permission to run the vxtunefs
command. We recommend this selective, more secure approach for granting access to
powerful commands.
◆ You must enable Quick I/O on the file system. Quick I/O is enabled automatically at file
system mount time.
If you have correctly enabled Quick I/O on your system, you can proceed to enable Cached Quick
I/O as follows:
◆ Set the file system Cached Quick I/O flag, which enables Cached Quick I/O for all files in the
file system.
Setting the file system Cached Quick I/O flag enables caching for all files in the file system.
You must disable Cached Quick I/O on individual Quick I/O files that do not benefit from
caching to avoid consuming memory unnecessarily. This final task occurs at the end of the
enabling process.
Usage Notes
◆ Do not enable Cached Quick I/O if Oracle is using Oracle Disk Manager.
Enabling and Disabling the qio_cache_enable Flag
As superuser (root), set the qio_cache_enable flag using the vxtunefs command after
you mount the file system.
▼ To enable the qio_cache_enable flag for a file system
Use the vxtunefs command as follows: