Veritas™ File System 5.0.1 Administrator's Guide

Note: Some of the commands have changed or been removed between the 4.1
release and the 5.0 release to make placement policy management more
user-friendly. The following commands have been removed: fsrpadm, fsmove, and
fssweep. The output of the queryfile, queryfs, and list options of the fsapadm
command now print the allocation order by name instead of number.
DST allows administrators of multi-volume VxFS file systems to manage the
placement of files on individual volumes in a volume set by defining placement
policies. Placement policies control both initial file location and the circumstances
under which existing files are relocated. These placement policies cause the files
to which they apply to be created and extended on specific subsets of a file system's
volume set, known as placement classes. The files are relocated to volumes in
other placement classes when they meet the specified naming, timing, access rate,
and storage capacity-related conditions.
You make a VxVM volume part of a placement class by associating a volume tag
with it. For file placement purposes, VxFS treats all of the volumes in a placement
class as equivalent, and balances space allocation across them. A volume may
have more than one tag associated with it. If a volume has multiple tags, the
volume belongs to multiple placement classes and is subject to allocation and
relocation policies that relate to any of the placement classes. Multiple tagging
should be used carefully.
See “Placement classes” on page 145.
VxFS imposes no capacity, performance, availability, or other constraints on
placement classes. Any volume may be added to any placement class, no matter
what type the volume has nor what types other volumes in the class have. However,
a good practice is to place volumes of similar I/O performance and availability in
the same placement class.
Note: Dynamic Storage Tiering is a licensed feature. You must purchase a separate
license key for DST to operate. See the Veritas Storage Foundation Release Notes.
The Using Dynamic Storage Tiering Symantec Yellow Book provides additional
information regarding the Dynamic Storage Tiering feature, including the value
of DST and best practices for using DST. You can download Using Dynamic Storage
Tiering from the following Web page:
http://www.symantec.com/enterprise/yellowbooks/index.jsp
Dynamic Storage Tiering
About Dynamic Storage Tiering
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