HP StorageWorks HSG60 and HSG80 Array Controller and Array Controller Software Troubleshooting Guide (EK-G80TS-SA. C01, March 2005)

Glossary
289HSG60 and HSG80 Array Controller and Array Controller Software Troubleshooting Guide
LRU
Least recently used. A cache term used to describe the block replacement policy for read
cache.
LUN
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 task I/O
operations. Each task in the system must establish its own correspondence between logical
unit numbers and physical devices.
See also logical unit.
maintenance terminal
An EIA-423-compatible terminal used with the controller. This terminal is used to identify
the controller, enable host paths, enter configuration information, and check controller
status. The maintenance terminal is not required for normal operations.
See also local terminal and local connection.
mass storage control protocol
See MSCP.
Mbps
Approximately one million (10
6
) bits per second—that is, megabits per second.
MBps
Approximately one million (10
6
) bytes per second—that is, megabytes per second.
member
A container that is a storage element in a RAID array.
metadata
The data written to a disk for the purposes of controller administration. Metadata improves
error detection and media defect management for the disk drive. Metadata is also used to
support storageset configuration and partitioning. Nontransportable disks also contain
metadata to indicate they are uniquely configured for HP StorageWorks environments.
Metadata can be thought of as data about data.
mirrored writeback caching
A method of caching data that maintains two copies of the cached data. The copy is
available if either cache module fails.
mirroring
The act of creating an exact copy or image of data.
mirrorset
See RAID level 1.