HP File System Extender (FSE) manual FSE disk buffer

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.

124 Migration, release, recall, and deletion