Veritas File System 5.0 Administrator's Guide (September 2006)

a file is designated by a SELECT statement is the only rule against which that file
is evaluated. Thus, rules whose purpose is to supersede a generally applicable
behavior for a special class of files should precede the general rules in a file
placement policy document.
The following XML snippet illustrates faulty rule placement with potentially
unintended consequences:
<?xml version="1.0"?>
<!DOCTYPE FILE_PLACEMENT_POLICY SYSTEM "placement.dtd">
<FILE_PLACEMENT_POLICY Version="5.0">
<RULE Name="GeneralRule">
<SELECT>
<PATTERN>*</PATTERN>
</SELECT>
<CREATE>
<ON>
<DESTINATION>
<CLASS>tier2</CLASS>
</DESTINATION>
</ON>
</CREATE>
...other statements...
</RULE>
<RULE Name="DatabaseRule">
<SELECT>
<PATTERN>*.db</PATTERN>
</SELECT>
<CREATE>
<ON>
<DESTINATION>
<CLASS>tier1</CLASS>
</DESTINATION>
</ON>
</CREATE>
...other statements...
</RULE>
</FILE_PLACEMENT_POLICY>
The GeneralRule rule specifies that all files created in the file system, designated
by <PATTERN>*</PATTERN>, should be created on tier2 volumes. The DatabaseRule
rule specifies that files whose names include an extension of .db should be created
on tier1 volumes. The GeneralRule rule applies to any file created in the file
system, including those with a naming pattern of *.db, so the DatabaseRule rule
Dynamic Storage Tiering
File placement policy rule and statement ordering
180