Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

■ special is a block special device
■ /mount_point is the location where the file system is mounted
■ -f forcibly unmounts the mount point
The following is an example of unmounting a file system:
To verify that the file system /db01 is not in use and then unmount the file
system:
# fuser -c /db01
/db01:
# umount /db01
About fragmentation
When free resources are initially allocated to files in a Veritas file system, they
are aligned in the most efficient order possible to provide optimal performance.
On an active file system, the original order is lost over time as files are created,
removed, or resized. As space is allocated and deallocated from files, the available
free space becomes broken into fragments. This means that space must be assigned
to files in smaller and smaller extents. This process is known as fragmentation.
Fragmentation leads to degraded performance and availability. The degree of
fragmentation depends on file system usage and activity.
How to control fragmentation
VxFS provides online reporting and optimization utilities to enable you to monitor
and defragment a mounted file system. These utilities are accessible through the
file system administration command, fsadm. Using the fsadm command, you can
track and eliminate fragmentation without interrupting user access to the file
system.
Types of fragmentation
VxFS addresses two types of fragmentation:
■ Directory Fragmentation
As files are created and removed, gaps are left in directory inodes. This is
known as directory fragmentation. Directory fragmentation causes directory
lookups to become slower.
■ Extent Fragmentation
61Setting up databases
About fragmentation