swapping

Hot swapping (frequently inaccurately called hot plugging) is replacing or adding components without stopping or shutting down the system. With the appropriate software installed on the computer, a user can plug and unplug such components without rebooting. Specifically, hot swapping describes inserting and/or removing components without interruption to the system. A well-known example of this hot swap functionality is the Universal Serial Bus (USB) that allows users to add or remove peripheral components such as a mouse, keyboard, printer, or portable hard drive; depending upon the supplier such devices are characterized as hot-swappable or hot-pluggable.
Hot plugging on the other hand describes only the addition of components that would expand the system without significant interruption to the system.Computer components are usually cold-pluggable since the computer system must be powered down to add or remove them. Most components in computer systems, such as CPUs and memory, are only cold-pluggable. However it is common for high-end servers and mainframes to feature hot-swappable capability for other components, such as PCIe and SATA drives.

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