(alternating current) (n.) Power supplied to the computer through an electrical outlet.

active cluster

(n.) A pair of identical high-availability servers that offer NAS services to client communities. In the event of a failure, the surviving server takes on the services and client community of its failed peer.


(n.) The storage system that attaches to the Sun StorageTek 5320 NAS Appliance or the Sun StorageTek 5320 NAS Cluster Appliance. The array consists of one or two Sun StorEdge 5300 RAID Controller Enclosures (CUs) that, optionally, can be connected to up to six Sun StorEdge 5300 Expansion Enclosures (EUs). An array can contain a mixture of EUs containing all Fibre Channel or all SATA disk drives.


(American wire gauge) (n.) A unit for measuring the thickness of wire.


(n.) A pair of identical servers providing redundant high-availability NAS services with failover protection.


(1) (n.) The manner in which the software and hardware of an information processing system are organized and interconnected. (2) (n.) The physical and logical arrangement of programs and devices that make up a data processing system. (3) (n.) The devices and programs that make up a system, subsystem, or network.


(controller unit) (n.) The Sun StorEdge 5300 RAID Controller Enclosure, which contains two controllers.


(direct current) (n.) Power typically supplied through a DC adapter or battery.


(n.) A software program that enables a computer to communicate with a peripheral device. Examples include a SCSI driver, a CD-ROM driver, and printer drivers.

dual head

(adj.) A reference to a pair of clustered servers. Servers can be referred to as "heads."


(expansion unit) (n.) The Sun StorEdge 5300 Expansion Enclosure, which contains hard drives in RAID-5 groups. An expansion unit can contain all Fibre Channel hard drives or all SATA hard drives.


(n.) A detectable physical change in hardware or software that disrupts normal (proper) operation. A failure is repaired by the replacement of a physical component or software.

Fast Ethernet (single and multiport)

(n.) A high-speed version of Ethernet transmitting data at 100 Mbps. Fast Ethernet networks use the same media access control method that 10BASE-T Ethernet networks use but achieve 10 times the data transmission speed.

flash memory

(n.) A special type of read-only memory (ROM) that enables users to upgrade the information contained in the memory chips.


(1) (n.) A way of accessing a network. (2) (n.) A configuration that enables a NAS server to share storage over a network.


(gigabyte) (n.) A unit of information equal to 1024 megabytes.

Gigabit Ethernet

(n.) An Ethernet technology that enables data transfer rates of up to 1 Gbps using optical fiber cable or unshielded twisted-pair cable.


(v.) To replace a failed component without interruption of system service.

interface cable

(n.) A cable designed to connect a computer to a peripheral device, or a peripheral device to another peripheral device, allowing each device to communicate with the other.


(kilobyte) (n.) A unit of information equal to 1024 bytes.


(liquid crystal display) (n.) A low-power display technology that uses rod-shaped crystal molecules that change their orientation when an electrical current flows through them.


(light-emitting diode) (n.) A semiconductor device that converts electrical energy into light.


(megabyte) (n.) A unit of information equivalent to 1,048,576 bytes or 1024 kilobytes. Most uses of "megabyte," however, refer to exactly 1 million bytes.


(megahertz) (n.) A measure of frequency equivalent to 1 million cycles per second.


(n.) A large circuit board that contains the computer's central processing unit (CPU), microprocessor support chips, random-access memory (RAM), and expansion slots.


(Mean Time Between Failures) (n.) The estimated time a device operates before a failure occurs.


(network-attached storage) (n.) A storage appliance that connects directly to the network. NAS does not usually perform network directory services or function as an application server; instead, it augments storage capacities. Quick and easy to set up, NAS appliances also typically provide cross-platform file sharing.


(network interface card) (n.) An adapter that lets you connect a network cable to a microcomputer. The card includes encoding and decoding circuitry and a receptacle for a network cable connection.


(adj.) Refers to data created by combining the bits in the information to be stored and creating a small amount of data from which the rest of the information can be extracted.


(Redundant Array of Independent Disks) (n.) A group of hard disks under the control of array management software that work together to improve performance and decrease the odds of losing data to mechanical or electronic failure by using techniques such as data striping.


(n.) The most commonly used RAID implementation. RAID-5 uses striping and parity information.


(random access memory) (n.) Semiconductor-based memory that can be read and written by the microprocessor or other hardware devices. Generally understood to refer to volatile memory, which can be written as well as read.


(storage area network) (n.) A network that includes various storage devices shared by multiple servers.


(Small Computer Systems Interface) (n.) A standard interface for PCs that enables you to connect up to 15 peripheral devices, such as CD-ROM drives.

SCSI bus

(n.) A pathway between SCSI hardware devices.

SCSI host adapter

(n.) A printed circuit board (also called an interface card) that enables the computer to use a peripheral device for which it does not already have the necessary connections or circuit boards.


(n.) Priority number (address) of a SCSI device in a SCSI device chain. Only one device at a time can transmit through a SCSI connection (port), and priority is given to the device with the highest priority address. SCSI IDs range from 0 to 15, and each SCSI device must be given a unique and unused SCSI ID.

single head

(adj.) A reference to a single server or "head."


(server message block) (n.) A Microsoft-compatible network protocol for exchanging files. SMB is typically used by Windows for Workgroups, OS/2 Warp Connect, and DEC Pathworks.


(n.) A RAID-based method for data storage in which data is divided into "stripes." One stripe is written to the first drive, the next to the second drive, and so on. The primary advantage of striping is the ability for all drives in the array to process reads and writes simultaneously.


(n.) The electrical connection at each end of the SCSI bus, composed of a set of resistors on internal SCSI devices or an active or passive SCSI terminator block on external SCSI devices.