Compaq StorageWorks Data Replication Manager HSG80 ACS Version 8.5P Operations Guide

Glossary G–9
logical unit A physical or virtual device addressable through a target ID number. LUNs
use their target’s bus connection to communicate on the SCSI bus.
Logical Unit Number Abbreviated LUN. A value that identifies a specific logical unit belonging to
a SCSI target ID number. A number associated with a physical device unit
during a task’s I/O operations. Each task in the system must establish its own
correspondence between logical unit numbers and physical devices.
LOG_UNIT A CLI command switch that (when enabled) assigns a single, dedicated log
unit for a particular association set. The association set members must all be
in the NORMAL error mode (not failsafe).
See also write history logging.
long distance mirroring Also known as peer-to-peer remote copy.
See also remote copy sets
loop See arbitrated loop.
loop_ID A seven-bit value numbered contiguously from zero to 126-decimal and
represent the 127 legal AL_PA values on a loop (not all of the 256 hex values
are allowed as AL_PA values per FC-AL).
loop tenancy The period of time between the following two events:
when a port wins loop arbitration and when the port returns to a monitoring
state.
L_Port A node or fabric port capable of performing Arbitrated Loop functions and
protocols. NL_Ports and FL_Ports are loop-capable ports.
mini-merge As applied to the Data Replication manager: a term representing the data
transfers to be made whenever a target becomes inaccessible. Inaccessibility
would be both links or both target controllers going down. The transfers that
would have been made are instead logged into the association set’s assigned
log unit to wait until the remote copy set subsystem comes back online.
See fast failback, write history logging.
mirroring The act of creating an exact copy or image of data.
N_port A port attached to a node for use with point-to-point topology or fabric
topology.