VERITAS File SystemÖ 3.5 (HP OnlineJFS/JFS3.5) AdministratorÆs Guide (December 2002)

Chapter 8

Quick I/O for Databases

Cached Quick I/O For Databases

$ qioadmin -S

filename

=on

mount_point

To enable caching for the Quick I/O file /database01/names.dbf, type:

$ qioadmin -S names.dbf=ON /database01

To disable the caching for that file, enter:

$ qioadmin -S names.dbf=OFF /database01

To make the setting persistent across mounts, create a qiotab file, /etc/vx/qioadmin, to list files and their

caching advisories. Based on the following example, the file /database/sell.dbf will have caching turned

on whenever the file system /database is mounted:

device=/dev/vx/dsk/datadg/database01

dates.dbf,off

names.dbf,off

sell.dbf,on

NOTE The cache advisories operate only if Cached Quick I/O is enabled for the file system. If the

qio_cache_enable flag is zero, Cached Quick I/O is OFF for all the files in that file system even

if the individual file cache advisory for a file is ON.

To check on the current cache advisory settings for a file, enter:

$ qioadmin -P names.dbf /database01

names.dbf,OFF

To check the setting of the qio_cache_enable flag for a file system, enter:

$ vxtunefs -p /database01

qio_cache_enable = 1

For more information on the format of the /etc/vx/qioadmin file and the command syntax, see the qioadmin

(1) manual page.

NOTE Check the setting of the flag qio_cache_enable using the vxtunefs command, and the

individual cache advisories for each file, to verify caching.

Tuning Cached Quick I/O

Not all database files can take advantage of caching. Performance may even degrade in some instances (due

to double buffering, for example). Determining which files and applications can benefit from Cached Quick

I/O requires that you first collect and analyze the caching statistics.

See the qiostat (1) man page for information on gathering statistics, and the VERITAS Editions products

documentation for a description of the Cached Quick I/O tuning methodology.