VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Determining Candidates for Cached Quick I/O Prerelease 8 September 2005, 8:54am
116 VERITAS Storage Foundation for Oracle Administrator’s Guide
Determining Candidates for Cached Quick I/O
Determining which files can benefit from Cached Quick I/O is an iterative process that varies with
each application. For this reason, you may need to complete the following steps more than once to
determine the best possible candidates for Cached Quick I/O.
Prerequisites
◆ You must enable Cached Quick I/O for the file systems. See “Enabling Cached Quick I/O on
the File System” on page 113.
Usage Notes
◆ See the qiostat(1M) manual page for more information.
Collecting I/O Statistics
▼ To collect statistics needed to determine files that benefit from Cached Quick I/O
1. Reset the qiostat counters by entering:
$ /opt/VRTS/bin/qiostat -r /mount_point/filenames
2. Run the database under full normal load and through a complete cycle (24 to 48 hours in most
cases) to determine your system I/O patterns and database traffic in different usage categories
(for example, OLTP, reports, and backups) at different times of the day.
3. While the database is running, run qiostat -l to report the caching statistics as follows:
$ /opt/VRTS/bin/qiostat -l /mount_point/filenames
or, use the -i option to see statistic reports at specified intervals:
$ /opt/VRTS/bin/qiostat -i n /mount_point/filenames
where n is time in seconds
Example
To collect I/O statistics from all database files on file system /db01:
$ /opt/VRTS/bin/qiostat -l /db01/*.dbf