Veritas™ File System 5.0.1 Administrator's Guide
Online system administration
VxFS provides command line interface (CLI) operations that are described
throughout this guide and in manual pages.
VxFS allows you to run a number of administration tasks while the file system is
online. Two of the more important tasks include:
■ Defragmentation
■ File system resizing
About defragmentation
Free resources are initially aligned and allocated to files in an order that provides
optimal performance. On an active file system, the original order of free resources
is lost over time as files are created, removed, and resized. The file system is
spread farther along the disk, leaving unused gaps or fragments between areas
that are in use. This process is known as fragmentation and leads to degraded
performance because the file system has fewer options when assigning a free
extent to a file (a group of contiguous data blocks).
VxFS provides the online administration utility fsadm to resolve the problem of
fragmentation.
The fsadm utility defragments a mounted file system by performing the following
actions:
■ Removing unused space from directories
■ Making all small files contiguous
■ Consolidating free blocks for file system use
This utility can run on demand and should be scheduled regularly as a cron job.
About file system resizing
A file system is assigned a specific size as soon as it is created; the file system may
become too small or too large as changes in file system usage take place over time.
VxFS is capable of increasing or decreasing the file system size while in use. Many
competing file systems can not do this. The VxFS utility fsadm can expand or
shrink a file system without unmounting the file system or interrupting user
productivity. However, to expand a file system, the underlying device on which
it is mounted must be expandable.
VxVM facilitates expansion using virtual disks that can be increased in size while
in use. The VxFS and VxVM packages complement each other to provide online
expansion capability. Use the vxresize command when resizing both the volume
Introducing Veritas File System
Using Veritas File System
30