User's Manual

HP StorageWorks File System Extender Software user guide 123
5 Migration, release, recall, and deletion
This chapter includes the following topics:
FSE operation basics, page 123
Migration, page 127
Release, page 129
Recall, page 136
Deletion, page 137
Resource allocation, page 140
System allocation and job priority policy, page 142
Partition allocation and job priority policy, page 144
Priority calculation, page 146
Multiple copying, page 147
HSM file system access modes, page 148
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.
FSE handles recalls in a different way. A recall job is started automatically each time an FSE user tries to
read an offline file, write to it or change its attributes. Apart from such implicit recalls on demand, FSE also
enables its users to trigger recalls of files before they are needed. These so-called explicit recalls can be
triggered with the fsefile command.
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.