bitfile segment An internal metadata structure, not normally visible, used by the Core Server to 
map contiguous pieces of a bitfile to underlying storage.
Bitfile Service Portion of the HPSS Core Server that provides a logical abstraction of bitfiles to 
its clients.
BMUX Block Multiplexer Channel
bytes between tape marks The number of data bytes that are written to a tape virtual volume before a tape 
mark is required on the physical media.
CAP Cartridge Access Port
cartridge A physical media container, such as a tape reel or cassette, capable of being 
mounted on and dismounted from a drive. A fixed disk is technically considered 
to be a cartridge because it meets this definition and can be logically mounted 
and dismounted.
central log The main repository of logged messages from all HPSS servers enabled to send 
messages to the Log Daemon.
class A type definition in Java. It defines a template on which objects with similar 
characteristics can be built, and includes variables and methods specific to the 
class.
Class of Service A set of storage system characteristics used to group bitfiles with similar logical 
characteristics and performance requirements together. A Class of Service is 
supported by an underlying hierarchy of storage classes.
cluster The unit of storage space allocation on HPSS disks.   The smallest amount of 
disk space that can be allocated from a virtual volume is a cluster.  The size of 
the cluster on any given disk volume is determined by the size of the smallest 
storage segment that will be allocated on the volume, and other factors.
configuration The process of initializing or modifying various parameters affecting the 
behavior of an HPSS server or infrastructure service.
COS Class of Service
Core Server An HPSS server which manages the namespace and storage for an HPSS system. 
The Core Server manages the Name Space in which files are defined, the 
attributes of the files, and the storage media on which the files are stored.  The 
Core Server is the central server of an HPSS system.  Each storage sub-system 
uses exactly one Core Server.
daemon A UNIX program that runs continuously in the background.
DB2 A relational database system, a product of IBM Corporation, used by HPSS to 
store and manage HPSS system metadata.
debug A log record message type used to log lower-level error conditions.
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