Glossary
This glossary provides definitions for the
terminology and abbreviations used in IBM
System Storage DS5000 and DS4000
publications.
If you do not find the term you are looking for, see
the IBM Glossary of Computing Termslocated at
the following Web site:
www.ibm.com/ibm/terminology
This glossary also includes terms and definitions
from:
vInformation TechnologyVocabulary by
Subcommittee 1, Joint TechnicalCommittee 1,
of the International Organization for
Standardization and the International
Electrotechnical Commission (ISO/IEC
JTC1/SC1). Definitions are identified by the
symbol (I) after the definition; definitions taken
from draft international standards, committee
drafts, and working papers by ISO/IEC
JTC1/SC1 are identified by the symbol (T) after
the definition, indicating that final agreement
has not yet been reached among the
participating National Bodies of SC1.
vIBM Glossary of Computing Terms.New York:
McGraw-Hill, 1994.
The following cross-reference conventions are
used in this glossary:
See Refers you to (a) a term that is the
expanded form of an abbreviation or
acronym, or (b) a synonym or more
preferred term.
See also
Refers you to a related term.
Abstract Windowing Toolkit(AWT). AJava graphical
user interface (GUI).
accelerated graphics port (AGP). Abus specification
that gives low-cost 3D graphics cards faster access to
main memory on personal computers than the usual
peripheral component interconnect (PCI) bus.AGP
reduces the overall cost of creating high-end graphics
subsystems by using existing system memory.
access volume. A special logical drive that allows the
host-agent to communicate with the controllers in the
storage subsystem.
adapter. Aprinted circuit assembly that transmits user
data input/output (I/O) between the internal bus of the
host system and the external Fibre Channel link and
vice versa.Also called an I/O adapter, host adapter, or
Fibre Channel adapter.
advanced technology (AT)bus architecture. A bus
standard for IBM compatibles. It extends the XT bus
architecture to 16 bits and also allows for bus
mastering, although only the first 16 MB of main
memory are available for direct access.
agent. Aserver program that receives virtual
connections from the network manager (the client
program) in a Simple Network Management
Protocol-Transmission Control Protocol/Internet Protocol
(SNMP-TCP/IP) network-managing environment.
AGP. Seeaccelerated graphics port.
AL_PA. Seearbitrated loop physical address.
arbitrated loop. One of three existing fibre-channel
topologies, in which 2 - 126 ports are interconnected
serially in a single loop circuit.Access to the Fibre
ChannelArbitrated Loop (FC-AL) is controlled by an
arbitration scheme. The FC-ALtopology supports all
classes of service and guarantees in-order delivery of
Fibre Channel frames when the originator and
responder are on the same FC-AL. The default topology
for the disk array is arbitrated loop.An arbitrated loop is
sometimes referred to as a Stealth Mode.
arbitrated loop physical address (AL_PA). An 8-bit
value that is used to uniquely identify an individual port
within a loop.A loop can have one or more AL_PAs.
array. Acollection of fibre-channel or SATA hard drives
that are logically grouped together.All the drives in the
array are assigned the same RAID level.An array is
sometimes referred to as a ″RAID set.″See also
redundant array of independent disks (RAID),RAID
level.
asynchronous write mode. Inremote mirroring, an
option that allows the primary controller to return a write
I/O request completion to the host server before data
has been successfully written by the secondary
controller.See also synchronous write mode,remote
mirroring,Global Copy,Global Mirroring.
AT. See advanced technology (AT)bus architecture.
ATA. See AT-attached.
AT-attached. Peripheraldevices that are compatible
with the original IBMAT computer standard in which
signals on a 40-pinAT-attached (ATA) ribbon cable
followed the timings and constraints of the Industry
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