Hub/Switch Installation Guide

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.
ObjectsmanagedbytheNSarefiles,filesets,directories,symboliclinks,junctions andhard
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,andlinks.FilesetsallowcollectionsofNSobjectstobemanagedasasingle
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 abitfileby specifyingthe bitfileIDand astarting addressand length.The reads
and writes to a bitfile are random, and BFS supports the notion of holes (areas of a bitfile
where no datahas been written). The BFSsupports parallel reading and writing ofdata 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 themigration, purging,and staging ofdata in astorage
hierarchy.