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
37
Defragmentation Utility
Free resources are originally aligned in the most efficient order possible and are allocated to files in
a way that is considered by the system to provide optimal performance. When a file system is
active for extended periods of time, new files are created, old files are removed, and existing files
grow and shrink. Over time, the original ordering of free resources is lost and the file system tends
to spread along the disk, leaving unused gaps or fragments between areas that are in use. This
process, known as fragmentation, leads to degraded performance because the file system has fewer
choices when selecting an extent (a group of contiguous data blocks) to assign to a file. You should
analyze the degree of fragmentation before creating new database files.
VxFS provides the online administration utility fsadm to resolve fragmentation problems. The
utility can be run on demand and should be scheduled regularly as a cron job.
Resizing Utility
Changes in database size can result in file systems that are too large or too small for the current
database. Without special utilities, expanding or shrinking a file system becomes a a matter of
stopping applications, offloading the contents of the file system, rebuilding the file system to a new
size, and then restoring the data. Data is unavailable to users while these administrative tasks are
performed.
The VxFS file system utility fsadm provides a mechanism to resize file systems without
unmounting them or interrupting users’ productivity. Because the VxFS file system can only be
mounted on one device, expanding a file system means that the underlying device must also be
expandable while the file system is mounted. Working with VxVM, VxFS provides online
expansion capability.
Cross-Platform Data Sharing
VERITAS Cross-Platform Data Sharing allows data to be serially shared among heterogeneous
systems where each system has direct access to the physical devices that hold the data. This feature
can be used only in conjunction with VERITAS Volume Manager. See the VERITAS Storage
Foundation Cross-Platform Data Sharing Administrator’s Guide for more information. Shared or
parallel access is possible for read-only data.
Cross-Platform Data Sharing provides the fastest way to use Oracle’s Transportable Tablespace
(TTS) feature for migrating databases to different platforms in Oracle 10g or for moving sets of
tablespaces between databases on the same platform in Oracle9i.
Quality of Storage Service (Optional)
The Quality of Storage Service (QoSS) feature is included with the Enterprise Edition.