Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

free space have less fragmentation and better extent allocation. Regular use of
the df command to monitor free space is desirable. Full file systems may have an
adverse effect on file system performance. Full file systems should therefore have
some files removed or should be expanded.
See the fsadm_vxfs(1M) manual page.
About monitoring fragmentation
Fragmentation reduces performance and availability. Regular use of fsadm's
fragmentation reporting and reorganization facilities is therefore advisable.
The easiest way to ensure that fragmentation does not become a problem is to
schedule regular defragmentation runs using the cron command.
Defragmentation scheduling should range from weekly (for frequently used file
systems) to monthly (for infrequently used file systems). Extent fragmentation
should be monitored with fsadmor the df -o scommands.
There are three factors that can be used to determine the degree of fragmentation:
■ Percentage of free space in extents that are less than eight blocks in length
■ Percentage of free space in extents that are less than 64 blocks in length
■ Percentage of free space in extents that are 64 or more blocks in length
An unfragmented file system will have the following characteristics:
■ Less than 1 percent of free space in extents that are less than eight blocks in
length
■ Less than 5 percent of free space in extents that are less than 64 blocks in
length
■ More than 5 percent of the total file system size available as free extents that
are 64 or more blocks in length
A badly fragmented file system will have one or more of the following
characteristics:
■ More than 5 percent of free space in extents that are less than 8 blocks in
length
■ More than 50 percent of free space in extents that are less than 64 blocks in
length
■ Less than 5 percent of the total file system size available as free extents that
are 64 or more blocks in length
The optimal period for scheduling extent reorganization runs can be determined
by choosing a reasonable interval, scheduling fsadm runs at the initial interval,
Tuning for performance
About tuning VxFS
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