Chapter 1 HPSS Basics
26 September 2002 HPSS Installation Guide
Release 4.5, Revision 2
Figure 1-3 The HPSS System
• Name Server (NS). The NS translates a human-oriented name to an HPSS object identifier.
Objects managed by the NS are files, filesets, directories, symbolic links, junctions and hard
links. The NS provides access verification to objects and mechanisms for manipulating
access to these objects. The NS provides a Portable Operating System Interface (POSIX)
view of the name space. This name space is a hierarchical structure consisting of
directories, files, and links. Filesets allowcollections of NSobjects to bemanaged as asingle
administrative unit. Junctions are used to link filesets into the HPSS name space.
• Bitfile Server (BFS). The BFS provides the abstraction of logical bitfiles to its clients. A
bitfile is identified by a BFS-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 reads
and writes to a bitfile are random, and BFS supports the notion of holes (areas of a bitfile
where no data has been written). The BFS supports parallel reading and writing of data to
bitfiles. The BFS communicates with the storage segment layer interface of the Storage
Server (see below) to support the mapping of logical portions of bitfiles onto physical
storage devices. The BFS supports the migration, purging, and staging of data in a storage
hierarchy.
