IBM System Storage Subsystem DS5020 - Manual (Page 238)

logical drive data to verify that it can be accessed, and
optionally scans the logical drive redundancy
information.
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.
micro channel architecture (MCA). Hardware that is
used for PS/2 Model 50 computers and above to
provide better growth potential and performance
characteristics when compared with the original
personal computer design.
Microsoft Cluster Server (MSCS). MSCS, a feature
of Windows NT Server (Enterprise Edition), supports the
connection of two servers into a cluster for higher
availability and easier manageability. MSCS can
automatically detect and recover from server or
application failures. It can also be used to balance
server workload and provide for planned maintenance.
mini hub. An interface card or port device that
receives short-wave fiber channel GBICs or SFPs.
These devices enable redundant Fibre Channel
connections from the host computers, either directly or
through a Fibre Channel switch or managed hub, over
optical fiber cables to the DS5020 Storage Server
controllers. Each DS5020 controller is responsible for
two mini hubs. Each mini hub has two ports. Four host
ports (two on each controller) provide a cluster solution
without use of a switch. Two host-side mini hubs are
shipped as standard. See also host port, gigabit
interface converter (GBIC), small form-factor pluggable
(SFP).
mirroring. A fault-tolerance technique in which
information on a hard disk is duplicated on additional
hard disks. See also remote mirroring.
model. The model identification that is assigned to a
device by its manufacturer.
MSCS. See Microsoft Cluster Server.
network management station (NMS). In the Simple
Network Management Protocol (SNMP), a station that
runs management application programs that monitor
and control network elements.
NMI. See non-maskable interrupt.
NMS. See network management station.
non-maskable interrupt (NMI). A hardware interrupt
that another service request cannot overrule (mask). An
NMI bypasses and takes priority over interrupt requests
generated by software, the keyboard, and other such
devices and is issued to the microprocessor only in
disastrous circumstances, such as severe memory
errors or impending power failures.
node. A physical device that allows for the
transmission of data within a network.
node port (N_port). A fibre-channel defined hardware
entity that performs data communications over the
fibre-channel link. It is identifiable by a unique worldwide
name. It can act as an originator or a responder.
nonvolatile storage (NVS). A storage device whose
contents are not lost when power is cut off.
N_port. See node port.
NVS. See nonvolatile storage.
NVSRAM. Nonvolatile storage random access
memory. See nonvolatile storage.
Object Data Manager (ODM). An AIX proprietary
storage mechanism for ASCII stanza files that are
edited as part of configuring a drive into the kernel.
ODM. See Object Data Manager.
out-of-band. Transmission of management protocols
outside of the fibre-channel network, typically over
Ethernet.
partitioning. See storage partition.
parity check. (1) A test to determine whether the
number of ones (or zeros) in an array of binary digits is
odd or even. (2) A mathematical operation on the
numerical representation of the information
communicated between two pieces. For example, if
parity is odd, any character represented by an even
number has a bit added to it, making it odd, and an
information receiver checks that each unit of information
has an odd value.
PCI local bus. See peripheral component interconnect
local bus.
PDF. See portable document format.
performance events. Events related to thresholds set
on storage area network (SAN) performance.
peripheral component interconnect local bus (PCI
local bus). A local bus for PCs, from Intel, that
provides a high-speed data path between the CPU and
up to 10 peripherals (video, disk, network, and so on).
The PCI bus coexists in the PC with the Industry
Standard Architecture (ISA) or Extended Industry
208 IBM System Storage DS5020 Storage Subsystem: Installation, User’s, and Maintenance Guide