hotplug

Hotplug is the capability to attach or detach hardware while a computer system is running. It is common for interfaces such as USB and SATA and is central to hot-pluggable or hot-swappable devices, which are designed to be replaced without powering down. Hotplug requires hardware support on the device and bus, along with operating system support to detect, configure, and use the device automatically.

Historically, hot-plugging began with SCSI and became widespread with USB. PCI and PCIe platforms later added hot-plug features to enable dynamic expansion and the replacement of components in servers and high-end workstations.

How it works: when a hot-plug event occurs, the bus controller signals the OS. The kernel or driver stack queries the new device, loads suitable drivers if needed, and assigns resources without reboot. For storage devices, safe removal procedures help prevent data loss by ensuring I/O operations have completed before the device is disconnected.

Safe use: always follow proper removal procedures: stop or unmount the device, then eject or physically remove. Many systems handle this automatically; in others, a dedicated hot-swap controller is required. Some devices, such as consumer USB drives, are designed for quick plug-in and removal, while enterprise storage and PCIe hot-swap trays emphasize redundancy and fault tolerance.

Limitations: not all hardware supports hot-plug; removing or inserting components during operation can cause instability if the system or drivers are not prepared. In well-designed environments, hot-plug improves uptime but requires careful management.