Veritas File System 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Quality of Storage Service
Customizing QoSS
Chapter 10140
Customizing QoSS
The following information is not essential to QoSS daily operation and management. This section describes
the relationship between the fssweep/fsmove utilities and the allocation policies and how files and
volumes are selected for relocation.
Mapping Relocation Policies to Allocation Policies
The fssweep and fsmove utilities use relocation policies to relocate existing files. Relocation uses the file
system’s allocation policies to determine the current location of each file and to move files to new locations.
Allocation policies also control newly created files. You can manage allocation policies using the fsapadm
utility (see the fsapadm(1M) manual page). In addition, some allocation policies are automatically
managed by the fssweep and fsmove utilities.
The fssweep and fsmove utilities create allocation policies that have names starting with the characters
fsmove_.
Each component volume has an allocation policy with a name created by appending the volume name to the
string fsmove_. For example, a volume named qoss1a has an allocation policy named fsmove_qoss1a.
The file system also has an allocation policy named fsmove_ALL that includes all component volumes.
VxFS default behavior is to assign fsmove_ALL to the file system’s mount point as the allocation policy to
be used for the newly created files.
By convention, fssweep and fsmove use volume names, so you need not specify the string fsmove_
when using these utilities.
The fsmove_ALL allocation policy allows newly created files to reside on any volume. The order in which
volumes are used is by ascending device index numbers. When the fssweep utility compares a newly
created file’s residence against a relocation policy’s list of source volumes, fssweep treats the files as if
they reside on the volume of lowest device index.
When you use the fssweep and fsmove utilities for the first time, the file system can already contain files
that have no allocation policies. The fssweep utility treats such files as though they reside in the
fsmove_ALL allocation policy.
If you use the fssweep and fsmove utilities infrequently, the default allocation policy allows overflow
as each volume becomes full. To the extent that this happens, it becomes ambiguous where the recently
created files really reside.
You can use the fsapadm utility to create allocation policies. Avoid using names that would be created
by fsmove. If a file was moved using fsapadm into an allocation policy whose name is something other
than the allocation policies used by fssweep and fsmove, the fssweep utility disregards the file when it
searches the file system.