Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

As files are created and removed, the free extent map for an allocation unit
changes from having one large free area to having many smaller free areas.
Extent fragmentation occurs when files cannot be allocated in contiguous
chunks and more extents must be referenced to access a file. In a case of
extreme fragmentation, a file system may have free space that cannot be
allocated.
How to monitor fragmentation
You can monitor fragmentation in VxFS by running reports that describe
fragmentation levels. Use the fsadm command to run reports on directory
fragmentation and extent fragmentation. The df command, which reports on file
system free space, also provides information useful in monitoring fragmentation.
Use the following commands to report fragmentation information:
■ fsadm -D, which reports on directory fragmentation.
■ fsadm -E, which reports on extent fragmentation.
■ /opt/VRTS/bin/fsadm [-F vxfs] -o , which prints the number of free extents
of each size.
Defragmenting a file system
You can use the online administration utility fsadm to defragment or reorganize
file system directories and extents.
The fsadm utility defragments a file system mounted for read/write access by:
■ Removing unused space from directories.
■ Making all small files contiguous.
■ Consolidating free blocks for file system.
The following options are for use with the fsadm utility:
Reorganizes directories. Directory entries are reordered to place
subdirectory entries first, then all other entries in decreasing order
of time of last access. The directory is also compacted to remove free
space.
Note: If you specify -d and -e, directory reorganization is always
completed first.
-d
Use in conjunction with the -d option to consider files not accessed
within the specified number of days as “aged” files. Aged files are
moved to the end of the directory. The default is 14 days.
-a
Setting up databases
About fragmentation
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