IBM TotalStorage DS4000 Hardware Maintenance Manual page 173

integrated drive electronics (IDE). A disk drive
interface based on the 16-bit IBM personal computer
Industry Standard Architecture (ISA) in which the
controller electronics reside on the drive itself,
eliminating the need for a separate adapter card. Also
known as an Advanced Technology Attachment
Interface (ATA).
Internet Protocol (IP). A protocol that routes data
through a network or interconnected networks. IP acts
as an intermediary between the higher protocol layers
and the physical network.
Internet Protocol (IP) address. The unique 32-bit
address that specifies the location of each device or
workstation on the Internet. For example, 9.67.97.103 is
an IP address.
interrupt request (IRQ). A type of input found on
many processors that causes the processor to suspend
normal processing temporarily and start running an
interrupt handler routine. Some processors have several
interrupt request inputs that allow different priority
interrupts.
IP. See Internet Protocol.
IPL. See initial program load.
IRQ. See interrupt request.
ISA. See Industry Standard Architecture.
Java Runtime Environment (JRE). A subset of the
Java Development Kit (JDK) for end users and
developers who want to redistribute the Java Runtime
Environment (JRE). The JRE consists of the Java virtual
machine, the Java Core Classes, and supporting files.
JRE. See Java Runtime Environment.
label. A discovered or user entered property value
that is displayed underneath each device in the
Physical and Data Path maps.
LAN. See local area network.
LBA. See logical block address.
local area network (LAN). A computer network
located on a user's premises within a limited
geographic area.
logical block address (LBA). The address of a logical
block. Logical block addresses are typically used in
hosts' I/O commands. The SCSI disk command
protocol, for example, uses logical block addresses.
logical partition (LPAR). (1) A subset of a single
system that contains resources (processors, memory,
and input/output devices). A logical partition operates
as an independent system. If hardware requirements
are met, multiple logical partitions can exist within a
system. (2) A fixed-size portion of a logical volume. A
logical partition is the same size as the physical
partitions in its volume group. Unless the logical
volume of which it is a part is mirrored, each logical
partition corresponds to, and its contents are stored on,
a single physical partition. (3) One to three physical
partitions (copies). The number of logical partitions
within a logical volume is variable.
logical unit number (LUN). An identifier used on a
small computer system interface (SCSI) bus to
distinguish among up to eight devices (logical units)
with the same SCSI ID.
loop address. The unique ID of a node in
fibre-channel loop topology sometimes referred to as a
loop ID.
loop group. A collection of storage area network
(SAN) devices that are interconnected serially in a
single loop circuit.
loop port. A node port (N_port) or fabric port (F_port)
that supports arbitrated loop functions associated with
an arbitrated loop topology.
LPAR. See logical partition.
LUN. See logical unit number.
MAC. See medium access control.
management information base (MIB). The
information that is on an agent. It is an abstraction of
configuration and status information.
man pages. In UNIX-based operating systems, online
documentation for operating system commands,
subroutines, system calls, file formats, special files,
stand-alone utilities, and miscellaneous facilities.
Invoked by the man command.
MCA. See micro channel architecture.
media scan. A media scan is a background process
that runs on all logical drives in the storage subsystem
for which it has been enabled, providing error detection
on the drive media. The media scan process scans all
logical drive data to verify that it can be accessed, and
optionally scans the logical drive data also.
medium access control (MAC). In local area networks
(LANs), the sublayer of the data link control layer that
supports medium-dependent functions and uses the
services of the physical layer to provide services to the
logical link control sublayer. The MAC sublayer
includes the method of determining when a device has
access to the transmission medium.
Metro Mirroring. This term is used to refer to a
remote logical drive mirror pair which is set up with
synchronous write mode. See also remote mirroring,
Global Mirroring.
MIB. See management information base.
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Glossary