User's Manual

124 Migration, release, recall, and deletion
With migration and recall jobs, the Partition Manager executes the appropriate sub-process—the job that
executes the defined task. When the FSE job completes its task, it is terminated. Release, however, is a
simpler process that does not require an FSE job. It is managed and executed locally by the Hierarchical
Storage Manager (HSM).
FSE disk buffer
FSE tries to unlock files on the HSM file system during migration, and de-allocate FSE media during recall
as fast as possible. For this purpose, while waiting for free resources, FSE copies file data and metadata to
a special directory on the consolidated FSE system or the FSE server. For example, during migration, files
are copied before they are written to the FSE media, and during recall, files are copied after they have
been read from FSE media.
Storage space in the special directory is called FSE disk buffer. FSE disk buffer plays an important role in
FSE implementation. It is managed by the Resource Manager and the temporary files in it are created and
removed by the Hierarchical Storage Managers and Back End Agents. The following figure shows how FSE
disk buffer is used during migration and recall.
Figure 24 Migration and recall path
Back End Agents automatically remove temporary data as soon as the particular process ceases to use
them. For example, during migration, the data are removed from the FSE disk buffer as soon as the
belonging files are written to the FSE media and their statuses are updated on the HSM file system. During
recall, the data are removed after the belonging file contents are recreated and the file statuses are
updated on the HSM file system.
NOTE: Similarly to migration and recall, FSE disk buffer is used for reorganization and duplication of FSE
media and for the redundant copy recreation.
The root directory of FSE disk buffer is platform-dependent.
Linux specific
The root directory of the FSE disk buffer is /var/opt/fse/diskbuf.
Windows specific
The root directory of the FSE disk buffer is %InstallPath%\var\diskbuf.
The value of %InstallPath% depends on the choice made in the FSE installation process. It defaults to
C:\Program Files\Hewlett-Packard\FSE.
IMPORTANT: To improve robustness and avoid potential data loss, a separate file system or volume (disk
partition) is usually allocated for the FSE disk buffer storage space.
TIP: To increase FSE job throughput and consequently speed of the FSE implementation, FSE disk buffer
can be extended by allocating additional file systems or volumes to its storage space. For details, see
chapter ”Monitoring and maintaining FSE”, section ”Extending storage space of FSE disk buffer” on
page 176.