Glossary   ANSI American National Standards Institute ATA The Advanced Technology Attachment interface. An IDE interface standard that defines a 40-pin connection, also available in an enhanced version called ATA-2 or Fast ATA that increases the transfer modes and introduced Logical Block Addressing. Enhanced IDE (EIDE) is synonomous with Fast ATA and most people refer to EIDE/ATA-2 when speaking of IDE. ATM Asynchronous Transfer Mode. A network connection and interface standard that offers a fast 100Mbit bandwidth over copper or fibre cabling. Used primarily for backbone connectivity rather than to the desktop.   Bandwidth The total maximum quantity of data that any device, wiring, interface, or communication standard can carry at any single point in time.   Data Warehousing A concept concerning a methodology of storing, sorting, and catagorising the excessive amounts of data that is generated by large businesses by careful management of the data into logical and helpful organisation-wide databanks and/or databases that allow the retrieval of information in an easier and more logical manner. Data Warehousing usually requires very high capacity, more intelligent, storage systems that have a high acessibility factor. Conceptually simple but notoriously difficult to implement unless accomplished by experts. Data Mart A smaller, more focused implementation of Data Warehousing usually aimed at the departmental level rather than across an enterprise. DB-9 A copper interface consisting of a simple plug with 9-pins. Used in many environments including Fibre Channel. (See also HSSD)   ECC (Error Checking/Correction) EEPROM Electrically Erasable Programmable Read Only Memory. A non-volatile chip that contains software information (such as Frimware) that may be erased and reprogrammed without the need for specialised equipment. A Flash utility is usually supplied by the manufacturer to access and reprogramme the chip with the firmware update available as a separate file.   FC-AL Fibre Channel Arbitrated Loop (FC-AL) is an ANSI-standard serial connectivity technology designed for data and communication intensive storage applications operating over fibre or copper media. See also Fibre Channel. FDDI Fibre Distributed Data Interface. A 100Mbps half duplex; 200Mbps full duplex network protocol used over UTP Category 5, STP, or Fibre cable. Firmware Software contained in a read-only memory (ROM) device. Ahardware version of software, or a cross between the two. Some firmware can be upgraded by the use of a Flash utility that rewrites the ROM to contain an updated version of the operating software. All storage devices such as CD-Recorders, digital tape drives, and of course hardware RAID controllers, contain firmware. See also EEPROM and Flash ROM. Fibre Channel Flash ROM Upgradable Read Only Memory module. Another name for an EEPROM. See also Firmware.   Gigabit Link Modules (GLM) Used in Fibre Channel environments, a GLM is used change the media interface. For example from copper to fibre by simply plugging in the copper cable on one side and the fibre cable on the other.   HIPPI HSSD A copper interface used in Fibre Channel that forms and alternative to the DB-9 interface connector.   IDE or EIDE Integrated Device Electronics or Enhanced Integrated Device Electronics. IDE Master device The first or primary device on an ATA or IDE bus that has priority over any other device or Slave on the same bus. IDE Slave device The second or secondary device on an ATA or IDE bus that has a lower priority under the Master device on the same bus. IP Internet Protocol. The standard communication protocol used over the Internet and in internal many networks worldwide. Invariably has its brother TCP (Transmission Control Protocol) alongside for support.   Logical Block Addressing (LBA) A method of translating the logical parameters of a hard drive such as the cylinder, head, and sector sizes into a usable format for system BIOS. Some hardware RAID controllers will allow you to specify the logical parameters you wish the operating system to 'see' to ensure compatibility. Despite a great deal of shouting from OS manufacturers concerning the 32-bit capabilities of their product many 32-bit systems still use or used a 16-bit file system or component after release. Popular culprits include Microsoft (Win 95), Apple (all MacOS prior to version 8.0), and even recent Sun Solaris revs have 16 bit fields for cylinders, heads, and sectors. So if the cylinders are reported as being 2^16+1, the system will think that the device has only 1 cylinder.   MTBF Mean Time Between Failures - the average time a manufacturer calaculates a device will operate before failure. A purely theoretical figure that is based on individual component life expectancy probability and has little to do with reality. According to MTBF figures no hard drive has ever failed yet, and the first every failure is expected in 50 years or so. Yes, of course it is. Rare evidence of a sense of humour among manufacturers.   NAS Network Attached Storage. A controller, device, or bridge that acts as a server and allows the attachment of standard storage systems such as hard drive, CD-ROM, DVD, tape systems etc. to be attached directly to a network rather than to a server running a standard NOS. NOS Network Operating System. An operating system that provides functions and services to multiple systems rather than simply only running its own hardware. UNIX, NT Server, Win2000 Server, and NetWare are examples of a NOS.   RAB - RAID Advisory Board The international body formed of major manufacturers and technology companies that oversees standards and specifications regarding RAID technology. Their web site is at http://www.raid-advisory.com/   Scratch Drives Scratch drives are working drives that usually offer high performance and large capacity. Used extensively in media environments when working with very large data formats or files such as digital video editing, high resolution image manipulation, and digital music recording. Data is migrated to stable long-term storage at the end of each session leaving the scratch drive clean. SNMP Simple Network Management Protocol   T10 Committee The standards group who are responsible for devising and ratifying SCSI standards and specifications. This ensures all SCSI devices offer compatibility across platforms and manufacturers. The T10 web site is at http://www.symbios.com/t10/ T11 Committee The standards group also know as the Fibre Channel Standards Committee who are responsible for devising and ratifying Fibre Channel standards and specifications. This ensures all Fibre Channel devices offer compatibility across platforms and manufacturers. Web site is at http://www.ncits.org/ Tag or Command Queue TCP Transmission Control Protocol - the brother of IP and apparently inseparable at birth.     RaidHelp © Copyright 1999-2000 Discovery Business Systems Ltd