Sun Microsystems Sun Fire X4200 - Manual (Page 193)

Glossary-21
U
uninterruptible power
supply (UPS) An auxiliary or backup power supply that provides electrical service over
extended system power outages. A UPS for a LAN or computer system
provides continuous power in the event of a power failure.
Universal Serial Bus
(USB) An external bus standard that supports data transfer rates of 450M bits per
second (USB 2.0). A USB port connects devices, such as mouse pointers,
keyboards, modems, and printers, to the computer system.
unshielded twisted
pair/shielded twisted
pair (UTP/STP) A type of Ethernet cable.
user account A record of essential user information that is stored on the system. Each user
who accesses a system has a user account.
User Datagram Protocol
(UDP) A connectionless, transport layer protocol that adds some reliability and
multiplexing to the Internet Protocol (IP). UDP enables one application
program to deliver, via IP, datagrams to another application program on
another machine. The Simple Network Management Protocol (SNMP) is
usually implemented over UDP.
user identification
(userid) A unique string identifying a user to a system.
user identification
number (UID
number) The number assigned to each user accessing a UNIX system. The system uses
UID numbers to identify, by number, the owners of files and directories.
user name A combination of letters, and possibly numbers, that identifies a user to the
system.
V
voltage regulator
module (VRM) An electronic device that regulates a system’s microprocessor voltage
requirements in order to maintain the correct voltage.
volume One or more disk drives that can be grouped into a unit for data storage.