HP StorageWorks Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide (AA-RPHZF-TE, March 2004)

Glossary
244 Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide
logical unit number
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, which represents the 127 legal AL_PA or
ALPA 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.
LUN
An acronym for logical unit number.
See logical unit number.
M-series switches
Fibre Channel Director and Edge switches made by McDATA and sold by HP.
mini-merge
As applied to the Data Replication Manager, a term representing the data transfers to be made from the write
history log when the target becomes available after having been unavailable. This happens when both links or
both target controllers have gone 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 continuously creating an exact physical copy or image of data.
mirrorset
1. A group of storage devices organized as duplicate copies of each other. Mirrorsets provide the highest level
of data availability at the highest cost. Another name for
RAID 1. Also called mirrored units or mirrored virtual disks.
2. Two or more physical disks configured to present one highly reliable virtual unit to the host.
3. A virtual disk drive consisting of multiple physical disk drives, each of which contains a complete and
independent copy of the entire virtual disk's data.
multiple intersite links
Each intersite link (ILS) is a fiber link between two switches. As applied to Data Replication Manager,
increasing bandwidth between switches is handled by adding connections between the switches, to a maximum
of two connections.