Chapter 1 HPSS Basics
26 September 2002 HPSS Installation Guide
Release 4.5, Revision 2
Figure 1-3 The HPSS System
NameServer (NS). The NS translates a human-oriented name to an HPSS object identifier.
Objectsmanaged 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 allow collections of NS objects to be managed as a single
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
portionsof 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
whereno 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
storagedevices. The BFS supports the migration, purging, and staging of data in a storage
hierarchy.