Hotpluggable

Hot-pluggable, also written hot-pluggable or hot-swappable, refers to hardware components that can be connected or removed from a system while it is running. The term describes devices designed to withstand electrical transients and to be safely seated or removed without powering down, enabling maintenance, upgrades, or expansion with minimal downtime. In practice, hot-pluggable components usually rely on dedicated hardware support such as backplanes, hot-swap controllers, and standardized interfaces, coupled with operating system support for dynamic device enumeration and safe removal.

Common hot-pluggable components include storage drives in hot-swap bays (SATA/SAS), redundant power supplies, cooling fans, line cards or modules in servers and network equipment, and PCIe or USB devices that support hot-plug operations. In data centers, hot-swappable drives and redundant power modules are essential for high availability.

To avoid data loss and electrical issues, hot-plug operations are typically accompanied by a graceful dismount or unmount, ensuring I/O completes before removal; the system may temporarily pause I/O or flush caches. Hot-plug controllers manage power sequencing and signaling to prevent arcing or bus contention.

Not all components are hot-pluggable; implementing hot-plug requires hardware, firmware, and software support, and some systems may require warnings or utilities to safely remove devices. Designs that support hot pluggability increase availability in servers and network gear, but require clear operating procedures and proper hardware design to minimize risk.