Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

Note: Veritas recommends that you use Veritas Extension for Oracle Disk Manager.

See “Setting up Veritas Extension for Oracle Disk Manager” on page 125.

How Quick I/O works

Veritas Quick I/O supports direct I/O and kernel asynchronous I/O and allows

databases to access regular files on a VxFS file system as raw character devices.

The benefits of using Quick I/O are:

■ Improved performance and processing throughput by having Quick I/O files

act as raw devices.

■ Ability to manage Quick I/O files as regular files, which simplifies

administrative tasks such as allocating, moving, copying, resizing, and backing

up datafiles.

Note: Veritas recommends using Oracle Disk Manager.

See “Converting Quick I/O files to Oracle Disk Manager files” on page 129.

How Quick I/O improves database performance

Quick I/O's ability to access regular files as raw devices improves database

performance by:

■ Supporting asynchronous I/O

■ Supporting direct I/O

■ Avoiding kernel write locks on database files

■ Avoiding double buffering

Supporting asynchronous I/O

Asynchronous I/O is a form of I/O that performs non-blocking system level reads

and writes, allowing the system to handle multiple I/O requests simultaneously.

Operating systems such as HP-UX provide kernel support for asynchronous I/O

on raw devices, but not on regular files. As a result, even if the database server is

capable of using asynchronous I/O, it cannot issue asynchronous I/O requests

when the database runs on file systems. Lack of asynchronous I/O significantly

degrades performance. Quick I/O lets the database server take advantage of

kernel-supported asynchronous I/O on file system files accessed using the Quick

I/O interface.

Using Veritas Quick I/O

About Quick I/O