HPSS Servers
HPSS servers include the Core Server, Migration/Purge Server, Gatekeeper, Location Server, Log Client, Log Daemon, Physical Volume Library, Physical Volume Repository, Mover, Storage System Management System Manager, and Startup Daemon. Figure 3: HPSS Components provides a simplified view of the HPSS system. Each major server component is shown, along with the basic control communication paths (thin arrowed lines). Infrastructure items (those components that “glue together” the distributed servers) are shown at the top of the cube.
Core Server. The Core Server provides several key sets of functionality.
First, the Core Server provides translation between human-oriented names and HPSS object identifiers. Name space objects managed by the Core Server are filesets, junctions, directories, files, hard links, and symbolic links. The Core Server provides access verification to objects and mechanisms for manipulating access to these objects via a Portable Operating System Interface (POSIX) view of the name space. This name space is a hierarchical structure consisting of directories, files, and links. These name space objects may exist within filesets that are connected via junctions.
Second, the Core Server provides the abstraction of logical bitfiles to its clients. A bitfile is identified by a Core Server generated name called a bitfile ID. Clients may reference portions of a bitfile by specifying the bitfile ID and a starting address and length. The Core Server supports random access to files and sparsely written files. It supports parallel reading and writing of data to bitfiles and performs the mapping of logical portions of bitfiles onto physical storage devices. The Core Server supports the migration, purging, and staging of data in a storage hierarchy (though the migration/purge policies are implemented through the Migration/Purge Server, a client to the Core Server).
Third, the Core Server provides a hierarchy of storage objects: storage segments, virtual volumes, and physical volumes. The Core Server translates storage segment references into virtual volume references and then into physical volume references, handles the mapping of physical resources into striped virtual volumes to allow parallel I/O to that set of resources, and schedules the