VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Chapter 1, VERITAS Storage Foundation for Oracle
Prerelease 8 September 2005, 8:54am VERITAS File System
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VERITAS File System
VERITAS File System (referred to as VxFS) is an extent-based, intent logging file system intended
for use in UNIX environments that deal with large volumes of data and that require high file system
performance, availability, and manageability. VxFS also provides enhancements that make file
systems more viable in database environments.
The VxFS file system included in this product has all the features of the optional HP OnlineJFS file
system product available from HP-UX; however, VxFS also includes Quick I/O, Storage
Checkpoints, and Storage Rollback. In this document, the terms “VxFS” and “HP OnlineJFS” are
synonymous in all contexts except in relation to Quick I/O, Storage Checkpoints, and Storage
Rollback.
The following sections provide a brief overview of VxFS concepts and features that are relevant to
database administration. For a more detailed description of VxFS and its complete feature set, see
the VERITAS File System Administrator’s Guide.
VERITAS Quick I/O
Databases can run on either file systems or raw devices. Database administrators often create their
databases on file systems because it makes common administrative tasks (such as moving, copying,
and backing up) easier. However, running databases on most file systems significantly reduces
database performance.
When performance is an issue, database administrators create their databases on raw devices. VxFS
with Quick I/O presents regular, preallocated files as raw character devices to the application.
Using Quick I/O, you can enjoy the management advantages of databases created on file systems
and achieve the same performance as databases created on raw devices. See “Using VERITAS
Quick I/O” on page 83 for more information.
Quick I/O can be used on Oracle9i and Oracle 10g. However, if you are using Oracle9i or Oracle
10g, we recommend that you use Oracle Disk Manager.
VERITAS Cached Quick I/O
ached Quick I/O allows databases to make more efficient use of large system memory while still
maintaining the performance benefits of Quick I/O. Cached Quick I/O provides an efficient,
selective buffering mechanism to back asynchronous I/O. Using Cached Quick I/O, you can enjoy
all the benefits of Quick I/O and achieve even better performance.
Cached Quick I/O is first enabled for the file system and then enabled on a per file basis. See“Using
VERITAS Cached Quick I/O” on page 109for more information.