User's Manual

hp StorageWorks File System Extender User Guide 109
5 Migration, release, recall, and deletion
This chapter includes the following topics:
• FSE operation basics, page 109
• Migration, page 112
• Release, page 114
• Recall, page 121
• Deletion, page 122
• Resource allocation, page 125
• System allocation and job priority policy, page 127
• Partition allocation and job priority policy, page 128
• Priority calculation, page 130
• Multiple copying, page 131
• HSM file system access modes, page 132
FSE operation basics
How does FSE function?
FSE keeps track of all migration and release tasks, thereby freeing users and administrators from constantly
monitoring the state and use of disk capacity. Once the file data is released, the file directory containing
information such as filename, access rights, time and date, and so on is maintained on the disk. This way
you can access and recall the files at any time. The file location—that is, whether its data resides on the
primary storage space (directly on the hard disk partition) or on the secondary storage space (media)—is
transparent to the user. You see network file systems or network drive letters (CIFS) in your list of system
drives. If you want to access one of these files, the file is either available on the file system or automatically
recalled from the fastest available secondary medium transparently to the user or application.
Policies
FSE uses a powerful sets of rules to automate migration and release jobs and the deletion of expired files:
the migration, release, and deletion policies.
• The migration policy defines a set of migration rules that govern the behavior of FSE’s automatic and
regular migration of files to FSE media.
• The release policy includes watermarks that control file data release jobs and rules for exclusion of
particular files from the release process.
• The deletion policy defines expiration periods for directories on the HSM file system, which are
considered when the deletion job is triggered by an FSE user.
Recalls are handled differently: they are started automatically when an FSE user wants to read an offline
file or write to it.
HSM lists
FSE manages migration and release jobs using lists of files that are candidates for migration or release,
handled by the Hierarchical Storage Manager (HSM). Both jobs are configured and controlled
independently.
FSE jobs
The essential jobs that are executed in FSE are migration, recall and release jobs. Migration and release
jobs are usually configured to be triggered when certain criteria are fulfilled. These criteria are defined by
the corresponding migration and release policies. In some situations, an explicit migration or release is
required, which can be started by an FSE user with the fsefile command. A recall job is always
triggered implicitly, when an FSE implementation user requests access to an offline file.
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