IBM DS8000 User Manual page 229

logical volume
The storage medium that is associated
with a logical disk drive. A logical
volume typically resides on one or more
storage devices. The DS8000 administrator
defines this unit of storage. The logical
volume, when residing on a
RAID-formatted array, is spread over the
drives in the array.
logical volume manager (LVM)
A set of system commands, library
routines, and other tools that allow the
user to establish and control logical
volume storage. The LVM maps data
between the logical view of storage space
and the physical disk drive module.
longitudinal redundancy check (LRC)
1) A method of error checking during
data transfer that involves checking parity
on a row of binary digits that are
members of a set that forms a matrix.
Longitudinal redundancy check is also
called a longitudinal parity check.
2) A mechanism that the DS8000 uses for
locating errors. The LRC checks the data
as it progresses from the host, through
theDS8000 controller, into the device
adapter, and to the array.
longwave laser adapter
A connector that is used between a host
and the DS8000 to support longwave
fibre-channel communication.
loop The physical connection between a pair of
device adapters in the DS8000 storage
unit. See also device adapter.
LPAR See logical partition.
LRC See longitudinal redundancy check.
LRU See least recently used.
LSS See logical subsystem.
LUN See logical unit number.
LVM See logical volume manager.
M
machine level control (MLC)
A database that contains the EC level and
configuration of products in the field.
machine reported product data (MRPD)
Product data gathered by a machine and
sent to a destination such as an IBM
support server or RETAIN
might include such information as feature
code information and product logical
configuration information.
mainframe
A computer, usually in a computer center,
with extensive capabilities and resources
to which other computers may be
connected so that they can share facilities.
(T)
maintenance analysis procedure (MAP)
A hardware maintenance document that
gives an IBM service representative a
step-by-step procedure for tracing a
symptom to the cause of a failure.
management console
See IBM System Storage Management
Console.
management information base (MIB)
1) A collection of objects that can be
accessed by means of a network
management protocol. (GC)
2) The MIB record conforms to the Open
Systems Interconnection (OSI) standard
defined by the International Organization
for Standardization (ISO) for the exchange
of information. See also simple network
management protocol.
MAP See maintenance analysis procedure.
master storage unit
The physical unit that controls the
creation of consistency groups in a Global
Mirror session. The master storage unit
sends commands to subordinate storage
units. A storage unit can be a master for
only one Global Mirror session. Contrast
with subordinate storage unit.
maximum consistency group drain time
The value in seconds that indicates the
maximum time that writes from the local
site are delayed to the remote site while
the current consistency group is being
formed at the remote site. When this time
is exceeded, the current attempt to form a
consistency group is ended and another
attempt is started. If this time is exceeded
five times, this maximum time is ignored
on the next attempt to form a consistency
group. The default value is the larger of
four minutes or two times the consistency
group interval time if this value is set to
zero.
®
. These records
201
Glossary