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Hot swapping and hot plugging are terms used to describe the functions of replacing computer system components without shutting down the system. More specifically, hot swapping describes replacing components without significant interruption to the system, while hot plugging describes the addition of components that would expand the system without significant interruption to the operation of the system. Once the appropriate software is installed on the computer, a user can plug and unplug the component without rebooting. A well-known example of this functionality is the Universal Serial Bus (USB) that allows users to add or remove peripheral components such as a mouse, keyboard, or printer. Computer components are usually described as cold-pluggable if the computer system must be powered down to add or remove them. The opposite term is hot-pluggable; hot-pluggable components can be added or removed without powering down the computer. In most computer systems, CPUs and memory are coldpluggable, but it is common for high-end servers and mainframes to feature hotplug capability of these components. Sometimes, devices that would be hot-pluggable may appear to only be cold-pluggable because of deficiencies in the system software. For example, PS/2 pointer devices are generally hot-pluggable (although they are not designed to be), but Microsoft Windows 95 and related operating systems would commonly have to be rebooted every time a PS/2 mouse was replaced, in order to detect the new mouse. The terms ''hot plug'' and ''cold plug'', can be taken to mean two different things, depending on the context. In a more generic context, ''hot plug'' is the ability to add or remove hardware without powering down the system, while ''cold plug'' is the inability to do so. In the context of comparing certain hot-pluggable devices, however, ''hot plug'' can be taken to mean the ability of the system to autonomously detect the addition or removal of hardware as it occurs, while ''cold plug'' can be taken to mean the ability to add or remove devices without powering down or rebooting the system, but the inability of the system to detect these changes, in which case the system operator would have to tell the system software that the change has occurred. ==Reasons for hot-swapping== Hot swapping is used whenever it is desirable to change the configuration or repair a working system without interrupting its operation. It may simply be for convenience of avoiding the delay and nuisance of shutting down and then restarting complex equipment or because it is essential for equipment, such as a server, to be continually active. Hot swapping may be used to add or remove peripherals or components, to allow a device to synchronize data with a computer, and to replace faulty modules without interrupting equipment operation. Equipment may be designed with redundancy so that in the event of the failure of a component, other parts of the system carry out its functions while the faulty component is removed and a replacement connected. For example, computer RAID disk arrays allow a faulty disk to be hot-swapped for a new one; the new one is configured to become part of the array automatically or by user command. A machine may have dual power supplies, each adequate to power the machine; a faulty one may be hot-swapped. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hot swapping」の詳細全文を読む スポンサード リンク
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