You can specify a value for the Prefer attribute for the <IOTEMP> and <ACCESSTEMP> criteria, which gives preference to relocating files. The Prefer attribute can take two values: low or high. If you specify low, Veritas File System (VxFS) relocates the files with the lower I/O temperature before relocating the files with the higher I/O temperature. If you specify high, VxFS relocates the files with the higher I/O temperature before relocating the files with the lower I/O temperature. Symantec recommends that you specify a Prefer attribute value only if you are using solid state disks (SSDs).

See Prefer mechanism with solid state disks.

Different <PERIOD> elements may be used in the <IOTEMP> and <ACCESSTEMP> criteria of different RELOCATE statements within the same policy.

The following placement policy snippet gives an example of the Prefer criteria:

   <RELOCATE>
      ...
      <WHEN>
         <IOTEMP Type="nrbytes" Prefer="high">
            <MIN Flags="gteq"> 3.4 </MIN>
            <PERIOD Units="hours"> 6 </PERIOD>
         </IOTEMP>
      </WHEN>
   </RELOCATE>

If there are a number of files whose I/O temperature is greater than the given minimum value, the files with the higher temperature are first subject to the RELOCATE operation before the files with the lower temperature.