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The Tivoli Space Manager Hierarchical Storage Management (HSM) client migrates files from your local file system to storage and recalls them either automatically or selectively. Migrating files to a distributed storage device frees space for new data on your local file system, and takes advantage of lower-cost storage resources that are available in your network environment.
Your Tivoli Storage Manager (TSM) administrator defines management classes to files. You, as root user:
These options and settings determine which files are eligible for automatic migration, the order in which files are migrated, where the migrated files are stored, and how much free space is maintained on your local file system. You prioritize files for migration by their file size, or by the number of days since your files were last accessed. Stub files that contain the necessary information to recall your migrated files remain on your local file system so that the files appear to reside locally. When you access migrated files, they are recalled automatically to your local file system. Contrast this with archiving, which completely removes files from your local file system.
The HSM client provides space management services for locally-mounted file systems, and it migrates regular files only. It does not migrate character special files, block special files, named pipe files, or directories.
File migration, unlike file backup, does not protect against accidental file deletion, file corruption, or disk failure. Continue to back up your files whether they reside on your local file system or in storage. You can use the Tivoli Storage Manager backup-archive client to back up and restore migrated files in the same manner as you would back up and restore files that reside on your local file system. If you accidentally delete stub files from your local file system, or if you lose your local file system, you can restore the stub files.
For planned processes, such as storing a large group of files in storage and returning them to your local file system for processing, use the archive and retrieve processes. You can use the backup-archive client to archive and retrieve copies of migrated files in the same manner as you would archive and retrieve copies of files that reside on your local file system.