hotunplug

Hot-unplug, or hot-unplugging, is the process of disconnecting a hardware device from a powered-on computer system without shutting the system down. The term is commonly contrasted with cold unplugging, which requires powering off. Hot-unplug is supported when hardware and software are designed to handle dynamic device removal. It is widely used for peripheral devices and removable media, and is particularly important in environments where downtime is costly.

Support for hot-unplug relies on both hardware and software mechanisms. Hardware backplanes and controllers detect device insertion and removal, and interfaces such as USB, USB-C, SATA with hot-plug support, PCI Express hot-plug, and certain NVMe backplanes enable safe removal. The operating system typically provides a safe-removal workflow to unmount storage, flush caches, and prepare the device for removal while preserving data integrity. Some devices can be removed without a formal eject step if the system is configured accordingly, but best practice is to use the provided safe-removal or ejection procedure.

Risks associated with hot-unplug include data loss, file-system corruption, and potential hardware damage if a device is removed during active input/output operations. Mitigation strategies include unmounting volumes, closing applications that may be using the device, using the operating system’s safely remove hardware feature, and relying on hardware designed for hot-unplug in critical applications. In server environments, hot-unplug may be supported alongside redundant paths and failover features to minimize disruption.

Related terms include hot-plug and hot-swapping, which describe the insertion or replacement of components while powered. See also hot plug, hot swap, and removable media.