Glossary 191MBR — Master boot record.memory address — A specific location, usually expressed as a hexadecimal number, inthe system’s RAM.memory module — A small circuit board containing DRAM chips that connects to thesystem board.memory — An area in your system that stores basic system data. A system can containseveral different forms of memory, such as integrated memory (ROM and RAM) andadd-in memory modules (DIMMs).memory key — A portable flash memory storage device integrated with a USBconnector.MHz — Megahertz.mirroring — A type of data redundancy in which a set of physical drives stores dataand one or more sets of additional drives stores duplicate copies of the data. Mirroringfunctionality is provided by software. See also striping and RAID.mm — Millimeter(s).ms — Millisecond(s).NAS — Network Attached Storage. NAS is one of the concepts used for implementingshared storage on a network. NAS systems have their own operating systems,integrated hardware, and software that are optimized to serve specific storage needs.NIC — Network interface controller. A device that is installed or integrated in asystem to allow connection to a network.NMI — Nonmaskable interrupt. A device sends an NMI to signal the processor abouthardware errors.ns — Nanosecond(s).NVRAM — Nonvolatile random-access memory. Memory that does not lose itscontents when you turn off your system. NVRAM is used for maintaining the date,time, and system configuration information.parity — Redundant information that is associated with a block of data.parity stripe — In RAID arrays, a striped hard drive containing parity data.partition — You can divide a hard drive into multiple physical sections calledpartitions with the fdisk command. Each partition can contain multiple logical drives.You must format each logical drive with the format command.PCI — Peripheral Component Interconnect. A standard for local-busimplementation.PDU — Power distribution unit. A power source with multiple power outlets thatprovides electrical power to servers and storage systems in a rack.
