Hitachi 9900 manual Glossary, Switch, Synchronous, Veritas, Virtual Logical Volume Image Manager

Glossary

Switch

A switch is a network device that examines and forwards packets between LAN segments.

Synchronous

Synchronous communications occur when the transmission of data between two devices is synchronized with a clocking scheme or other technique. The sender and receiver need to synchronize with one another before data is sent. In synchronous communication, the bit stream and the clock pulse are synchronized by a special bit transition pattern in the digital signal, creating an exactly timed stream of bits from the sending device to the receiving device. An example of such a mechanism is bipolar encoding. Synchronous communication is either character or bit oriented. Character oriented synchronous transmissions are used to send blocks of characters, such as those found in ASCII (American Standard Code for Information Interchange) files. Bit-oriented synchronous communication is used primarily for the transmission of binary data. See also Asynchronous Remote Copy and Hitachi TrueCopy™.

TCO

Total cost of ownership or TCO is a computer industry financial method of identifying the cost of operating computer equipment. TCO includes depreciated capital costs, manpower expense, power costs, communication costs, overhead, etc.

TCP

Transmission Control Protocol or TCP is a transport layer component of the Internet’s TCP/IP protocol suite. It sits above IP in the protocol stack and provides reliable data delivery services over connection-oriented links. TCP uses IP to deliver information across a network and makes up for the deficiency of IP, providing a guarantee of reliable delivery services that IP does not. TCP messages and data are encapsulated into IP datagrams and IP delivers them across the network.

VERITAS®

A Mountain View, California software company that develops and supports volume and file management software products for a variety of UNIX® and Microsoft® Windows® platforms.

Virtual Logical Volume Image Manager

Virtual Logical Volume Image (VLVI) Manager is a software utility in the Hitachi Resource Manager™ package that allows for RAID configurations, and create, delete, verify, rebuild, tune, and abort operations. See also RAID and Hitachi Resource Manager.

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