Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

Enabling and disabling Cached Quick I/O for individual
files
After using qiostat or other analysis tools to determine the appropriate files for
Cached Quick I/O, you need to disable Cached Quick I/O for those individual files
that do not benefit from caching using the qioadmin command.
■ Enable Cached Quick I/O for the file system before enabling or
disabling Cached Quick I/O at the individual file level.
Prerequisites
■ You can enable or disable Cached Quick I/O for individual files
while the database is online.
■ You should monitor files regularly using qiostat to ensure that
a file's cache-hit ratio has not changed enough to reconsider
enabling or disabling Cached Quick I/O for the file.
■ Enabling or disabling Cached Quick I/O for an individual file is also
referred to as setting the cache advisory on or off.
■ See the qioadmin (1) manual page.
Usage notes
Setting cache advisories for individual files
You can enable and disable Cached Quick I/O for individual files by changing the
cache advisory settings for those files.
To disable Cached Quick I/O for an individual file
◆
Use the qioadmin command to set the cache advisory to OFF as follows:
$ /opt/VRTS/bin/qioadmin -S filename=OFF /mount_point
For example, to disable Cached Quick I/O for the file /db01/dbfile, set the
cache advisory to OFF:
$ /opt/VRTS/bin/qioadmin -S dbfile=OFF /db01
To enable Cached Quick I/O for an individual file
◆
Use the qioadmin command to set the cache advisory to ON as follows:
$ /opt/VRTS/bin/qioadmin -S filename=ON /mount_point
For example, running qiostatshows the cache hit ratio for the file
/db01/dbfilereaches a level that would benefit from caching. To enable
Cached Quick I/O for the file /db01/dbfile, set the cache advisory to ON:
$ /opt/VRTS/bin/qioadmin -S dbfile=ON /db01
85Improving DB2 database performance with Veritas Cached Quick I/O
Enabling and disabling Cached Quick I/O for individual files