NonStop S-Series Hardware Installation and FastPath Guide (G06.25+)

Glossary
HP NonStop S-Series Hardware Installation and FastPath Guide—529443-001
Glossary-61
logic board (LB)
logic board (LB). (1) See cluster switch logic board. (2) A printed wiring assembly (PWA)
on which computer circuits (chips and wiring) are mounted. One type of logic board is a
processor and memory board (PMB). Another type is a multifunction I/O board
(MFIOB).
logical device name. The name assigned to an I/O process during its configuration. Other
processes use the logical device name when issuing Guardian procedure calls to the
I/O process.
logical device number (ldev). For a device or named process, the index into the
destination control table (DCT); or more precisely, into the named resource list (NRL).
Each device or named process in the system has an ldev.
logical disk volume. A hardware device or device pair that provides persistent, highly
accessible storage for data on a medium that is either magnetic or optical.
logical interface (LIF). A process that allows an application or another process to
communicate with data communications hardware.
logical memory unit (LMU). A group of four memory units on an HP NonStop™ S-series
processor and memory board. Memory on a processor and memory board (PMB) is
divided into two LMUs. One LMU contains memory units in slots MS1 through MS4.
The other LMU contains memory units in slots MS5 through MS8. An LMU must have
memory units installed either in all of its slots or in none of its slots. See also memory
unit.
logical segment. A single data area consisting of one or more consecutive 128-kilobyte
unitary segments that is dynamically allocated by a process. The two types of logical
segments are selectable segments and flat segments. See also selectable segment
and flat segment.
logical network partitioning. An HP NonStop™ TCP/IPv6 feature that allows you to divide
the system into separately addressed IP subnetworks whereby applications have
access only to a defined set of network interfaces (IP addresses).
logical unit number (LUN). (1) A unique number used on a SCSI bus to differentiate
between devices on the bus. (2) The logical unit in the Enterprise Storage System
(ESS) that maps the LDEV onto a port. Specification of the port and LUN specifies an
LDEV.
login. The activity by which a user establishes a locally authenticated identity on a server.
Each login has one login name.
login name. A user name associated with a session.
logon sequence. The process through which the HP NonStop™ server to be managed is
determined, the security constraints to interact with that server are met, and a
connection with that server is established.