VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Chapter 14, Tuning for Performance
Prerelease 8 September 2005, 8:55am Tuning VxFS
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If your database is using one file system on a striped volume, you may only need to pay attention to
the file I/O activity statistics. If you have more than one file system, you may need to monitor
volume I/O activity as well.
First, use the qiostat -r command to clear all existing statistics. After clearing the statistics, let
the database run for a while during a typical database workload period. For example, if you are
monitoring a database with many users, let the statistics accumulate for a few hours during prime
working time before displaying the accumulated I/O statistics.
To display active file I/O statistics, use the qiostat command and specify an interval (using -i)
for displaying the statistics for a period of time. This command displays a list of statistics such as:
OPERATIONS FILE BLOCKS AVG TIME(ms)
FILENAME READ WRITE READ WRITE READ WRITE
/db01/cust1 218 36 872 144 22.8 55.6
/db01/hist1 0 1 0 4 0.0 10.0
/db01/nord1 10 14 40 56 21.0 75.0
/db01/ord1 19 16 76 64 17.4 56.2
/db01/ordl1 189 41 756 164 21.1 50.0
/db01/roll1 0 50 0 200 0.0 49.0
/db01/stk1 1614 238 6456 952 19.3 46.5
/db01/sys1 0 0 0 0 0.0 0.0
/db01/temp1 0 0 0 0 0.0 0.0
/db01/ware1 3 14 12 56 23.3 44.3
/logs/log1 0 0 0 0 0.0 0.0
/logs/log2 0 217 0 2255 0.0 6.8
File I/O statistics help identify files with an unusually large number of operations or excessive read
or write times. When this happens, try moving the “hot” files or busy file systems to different disks
or changing the layout to balance the I/O load.
Obtaining File I/O Statistics using VERITAS Extension for Oracle
Disk Manager
The odmstat command provides access to activity information on Oracle Disk Manager files on
VxFS systems. Refer to the odmstat(1M) manual page for more information. The command
reports statistics on the activity from the time that the files were opened by the Oracle Disk
Manager interface. The command has an option for zeroing the statistics. When the file is closed,
the statistics are discarded.
The odmstat command displays the following I/O statistics:
◆ Number of read and write operations
◆ Number of data blocks read and written