Hot-plugging, also known as Hot Swap, is a feature that allows users to remove and replace damaged hardware components such as hard drives, power supplies, or expansion cards without shutting down the system or cutting off power. This capability enhances the system’s ability for timely disaster recovery, scalability, and flexibility. For instance, advanced disk mirroring systems designed for high-end applications often offer hot-plugging functionality.
In academic terms, hot-plugging encompasses Hot Replacement, Hot Expansion, and Hot Upgrade. It was initially introduced in the server domain to improve server usability. In our everyday computers, USB interfaces are common examples of hot-plugging. Without hot-plugging, even if a disk is damaged and data loss is prevented, users still need to temporarily shut down the system to replace the disk. In contrast, with hot-plugging technology, users can simply open the connection switch or handle to remove the disk while the system continues to operate uninterrupted.
Implementing hot-plugging requires support in several aspects, including bus electrical characteristics, motherboard BIOS, operating system, and device drivers. Ensuring that the environment meets specific requirements allows the realization of hot-plugging. Current system buses partially support hot-plugging technology, especially since the 586 era when external bus expansion was introduced. Starting from 1997, new BIOS versions began supporting plug-and-play capabilities, though this support didn’t encompass full hot-plugging but only covered hot addition and hot replacement. However, this technology is the most commonly used in hot-plugging scenarios, thus overcoming the motherboard BIOS concern.
Regarding the operating system, support for plug-and-play was introduced with Windows 95. However, support for hot-plugging was limited until Windows NT 4.0. Microsoft recognized the importance of hot-plugging in the server domain and consequently, full hot-plugging support was added to the operating system. This feature continued through subsequent versions of Windows based on the NT technology, including Windows 2000/XP. As long as an operating system version above NT 4.0 is used, comprehensive hot-plugging support is provided. In terms of drivers, hot-plugging functionality has been integrated into drivers for Windows NT, Novell’s NetWare, and SCO UNIX. By selecting drivers compatible with these operating systems, the final element for achieving hot-plugging capability is fulfilled.
In ordinary computers, devices connected through USB (Universal Serial Bus) interfaces and IEEE 1394 interfaces can achieve hot-plugging. In servers, components that can be hot-plugged mainly include hard drives, CPUs, memory, power supplies, fans, PCI adapters, and network cards. When purchasing servers, it is crucial to pay attention to which components support hot-plugging, as this will significantly impact future operations.
Post time: Jul-21-2023
