|
Hot Spare
A hot spare or warm spare or hot standby is a component used as a failover mechanism to provide reliability in system configurations. The hot spare is active and connected as part of a working system. When a key component fails, the hot spare is switched into operation. More generally, a hot standby can be used to refer to any device or system that is held in readiness to overcome an otherwise significant start-up delay. Examples Examples of hot spares are components such as A/V switches, computers, network printers, and hard disks. The equipment is powered on, or considered "hot," but not actively functioning in (i.e. used by) the system. Electrical generators may be held on hot standby, or a steam train may be held at the shed fired up (literally hot) ready to replace a possible failure of an engine in service. Explanation In designing a reliable system, it is recognized that there will be failures. At the extreme, a complete system can be duplicated and kept up to date� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Failover
Failover is switching to a redundant or standby computer server, system, hardware component or network upon the failure or abnormal termination of the previously active application, server, system, hardware component, or network in a computer network. Failover and switchover are essentially the same operation, except that failover is automatic and usually operates without warning, while switchover requires human intervention. History The term "failover", although probably in use by engineers much earlier, can be found in a 1962 declassified NASA report. The term "switchover" can be found in the 1950s when describing '"Hot" and "Cold" Standby Systems', with the current meaning of immediate switchover to a running system (hot) and delayed switchover to a system that needs starting (cold). A conference proceedings from 1957 describes computer systems with both Emergency Switchover (i.e. failover) and Scheduled Failover (for maintenance). Failover Systems designers usually pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System Configuration
A system configuration (SC) in systems engineering defines the computers, processes, and devices that compose the system and its boundary. More generally, the system configuration is the specific definition of the elements that define and/or prescribe what a system is composed of. Alternatively, the term "system configuration" can be used to relate to a ''model'' (declarative) for abstract generalized systems. In this sense, the usage of the configuration information is not tailored to any specific usage, but stands alone as a data set. A properly-configured system avoids resource-conflict problems, and makes it easier to upgrade a system with new equipment. Sample configuration The following is a basic SC XML System Configuration: ''Description'': This provides information about a single "site" (MyHouse) and specifies that there is one host with ''user-setup'' and ''mysql-db'' components. The host must have an account on it for a user named ''mysql'', with appropriate paramete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A/V Switch
AV, Av or A.V. may refer to: Arts and entertainment * The abbreviation of audiovisual, possessing both a sound and a visual component * ''A.V.'' (film), a 2005 Hong Kong film directed by Pang Ho-Cheung * Adult video, an alternative name/synonym of a pornographic film * ''AV The Hunt'', a 2020 Turkish thriller film directed by Emre Akay Businesses and organizations * America Votes, an American 501(c)4 organization that promotes progressive causes * Ambulance Victoria, an ambulance service operated in the Australian state of Victoria * Anonymous for the Voiceless, a grassroots animal rights organization specializing in street activism * Aston Villa F.C. Aston Villa Football Club (commonly referred to as simply Villa) is a professional Association football, football club based in Aston, Birmingham, England. The club, founded in 1874, compete in the Premier League, the top tier of English foot ..., an English professional football club * AV Akademikerverlag GmbH & Co. KG an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic sets of operations known as Computer program, ''programs'', which enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the Computer hardware, hardware, operating system, software, and peripheral equipment needed and used for full operation; or to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of Programmable logic controller, industrial and Consumer electronics, consumer products use computers as control systems, including simple special-purpose devices like microwave ovens and remote controls, and factory devices like industrial robots. Computers are at the core of general-purpose devices ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Printer
A printer is a peripheral machine which makes a durable representation of graphics or text, usually on paper. While most output is human-readable, bar code printers are an example of an expanded use for printers. Different types of printers include 3D printers, inkjet printers, laser printers, and thermal printers. History The first computer printer designed was a mechanically driven apparatus by Charles Babbage for his difference engine in the 19th century; however, his mechanical printer design was not built until 2000. He also had plans for a curve plotter, which would have been the first computer graphics printer if it was built. The first patented printing mechanism for applying a marking medium to a recording medium or more particularly an electrostatic inking apparatus and a method for electrostatically depositing ink on controlled areas of a receiving medium, was in 1962 by C. R. Winston, Teletype Corporation, using continuous inkjet printing. The ink was a red sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, platters coated with magnetic material. The platters are paired with disk read-and-write head, magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual Block (data storage), blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small disk enclosure, rectangular box. Hard disk drives were introduced by IBM in 1956, and were the dominant secondary storage device for History of general-purpose CPUs, general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern er ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Generator
In electricity generation, a generator, also called an ''electric generator'', ''electrical generator'', and ''electromagnetic generator'' is an electromechanical device that converts mechanical energy to electrical energy for use in an external circuit. In most generators which are rotating machines, a source of kinetic power rotates the generator's shaft, and the generator produces an electric current at its output terminals which flows through an external circuit, powering electrical loads. Sources of mechanical energy used to drive generators include steam turbines, gas turbines, water turbines, internal combustion engines, wind turbines and even hand cranks. Generators produce nearly all of the electric power for worldwide electric power grids. The first electromagnetic generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday. The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coal-fired Power Station
A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide there are about 2,500 coal-fired power stations, on average capable of generating a gigawatt each. They generate about a third of the world's electricity, but cause many illnesses and the most early deaths per unit of energy produced, mainly from air pollution. World installed capacity doubled from 2000 to 2023 and increased 2% in 2023. A coal-fired power station is a type of fossil fuel power station. The coal is usually pulverized and then burned in a pulverized coal-fired boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines that turn generators. Thus chemical energy stored in coal is converted successively into thermal energy, mechanical energy and, finally, electrical energy. Coal-fired power stations are the largest single contributor to climate change, releasing approximately 12 billion tonnes of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hot Swapping
Hot swapping is the replacement or addition of components to a computer system without stopping, shutting down, or rebooting the system. Hot plugging describes only the addition of components to a running computer system. Components which have such functionality are said to be ''hot-swappable'' or ''hot-pluggable''; likewise, components which do not are ''cold-swappable'' or ''cold-pluggable''. Although the broader concept of hot swapping can apply to electrical or mechanical systems, it is usually mentioned in the context of computer systems. An example of hot swapping is the express ability to pull a Universal Serial Bus (USB) peripheral device, such as a thumb drive, mouse, keyboard, or printer out of a computer's USB slot without powering down the computer first. Most desktop computer hardware, such as CPUs and memory, are only cold-pluggable. However, it is common for mid to high-end servers and mainframes to feature hot-swappable capability for hardware componen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RAID
RAID (; redundant array of inexpensive disks or redundant array of independent disks) is a data storage virtualization technology that combines multiple physical Computer data storage, data storage components into one or more logical units for the purposes of data redundancy, performance improvement, or both. This is in contrast to the previous concept of highly reliable mainframe disk drives known as ''single large expensive disk'' (''SLED''). Data is distributed across the drives in one of several ways, referred to as RAID levels, depending on the required level of redundancy (engineering), redundancy and performance. The different schemes, or data distribution layouts, are named by the word "RAID" followed by a number, for example RAID 0 or RAID 1. Each scheme, or RAID level, provides a different balance among the key goals: reliability engineering, reliability, availability, computer performance, performance, and computer data storage#Capacity, capacity. RAID levels ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Time To Recovery
Mean time to recovery (MTTR) is the average time that a device will take to recover from any failure. Examples of such devices range from self-resetting fuses (where the MTTR would be very short, probably seconds), to whole systems which have to be repaired or replaced. The MTTR would usually be part of a maintenance contract, where the user would pay more for a system MTTR of which was 24 hours, than for one of, say, 7 days. This does not mean the supplier is guaranteeing to have the system up and running again within 24 hours (or 7 days) of being notified of the failure. It does mean the average repair time will tend towards 24 hours (or 7 days). A more useful maintenance contract measure is the maximum time to recovery which can be easily measured and the supplier held accountably. Note that some suppliers will interpret MTTR to mean 'mean time to respond' and others will take it to mean 'mean time to replace/repair/recover/resolve'. The former indicates that the supplier wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Tube
A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It takes the form of an evacuated tubular envelope of glass or sometimes metal containing electrodes connected to external connection pins. The type known as a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot cathode for fundamental Electronics, electronic functions such as signal amplifier, amplification and current Rectifier, rectification. Non-thermionic types such as vacuum phototubes achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light and measurement of its intensity. In both types the electrons are accelerated from the cathode to the anode by the electric field in the tube. The first, and simplest, vacuum tube, the diode or Flem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
