Hitachi 9900 manual Glossary, Logical Unit Number, Logical Volume, Lpar, Luse, Mips

Glossary

Logical Unit Number

See LUN.

Logical Volume

The storage medium associated with a logical disk drive. A logical volume typically resides on one or more storage devices. A host system sees a logical volume as a physical volume, although it does not correlate directly with a physical disk drive.

LUN

Logical Unit or Logical Unit Numbers. A SCSI term for the field in an identifying message that is used to select a logical unit on a given target.

LPAR

LPAR or logical partition is an IBM® ESA/390® term for a set of functions that create the programming environment that is defined by the ESA/390 architecture. ESA/390 architecture uses this term when more than one LPAR is established on an ESA/390 server. An LPAR is conceptually similar to a virtual machine environment, except that the LPAR is tied to one or more physical processors in a tightly coupled multiprocessor system. Also the LPAR does not depend on an operating system to create the virtual machine environment.

LUSE

LUN Size Expansion feature. This Lightning 9900 V Series feature allows standard-size

LUNs to be combined to create larger LUNs.

LRU

Least Recently Used. A policy for a caching algorithm that chooses to remove the data from cache which has the longest elapsed time since its last access. Least Recently Used algorithms are used in all major caching systems. The Lightning 9900 V Series LRU scheme keeps a table (in separate non-volatile memory) that chronicles the frequency of use of data in cache memory.

MAN

Metropolitan Area Networks. Networks within a metropolitan area, which might, for example, be used for a city government.

MIB

Management Information Base is a set of standards for detailed system information that is reported to a control console for SNMP compliance. Its intent is to provide common parameters for heterogeneous computer systems.

MIPS

Millions of Instructions Per Second (or MIPS) is a rough measure of processor performance within the same class of processor.

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