Hot swap

The hot-plugging (Hot Swap or Hot Swap) function allows users to remove and replace damaged hard disks, power supplies, or board components without shutting down the system and without interrupting the power supply. This improves the system's ability to recover from disasters in time. , scalability, and flexibility. For example, some disk mirroring systems for high-end applications can provide hot-swappable disks.

Specifically, the academic arguments are: Hot replacement, hot expansion, and hot upgrade. The earliest hot plugging was in the server field. It was proposed to improve server usability. Usually used computers have a USB interface, this interface can be hot-swappable. If there is no hot swap function, even if the disk is damaged, data will not be lost. Users still need to temporarily shut down the system so that the hard disk can be replaced. Using the hot swapping technology, simply open the connection switch or turn the handle to remove the data directly. Hard disk, and the system can still operate without interruption.

Hot swapping requires support in the following areas: bus electrical characteristics, motherboard BIOS, operating system, and device drivers. So we only need to make sure that the environment meets the above specific environment and we can implement hot plugging. The current system bus supports some of the hot-swap technologies, especially since the 586 era, the system bus has increased the expansion of the external bus, so our concerns can be eliminated in this regard. Since 1997, the new BIOS has added support for plug and play functionality. Although this plug and play support does not represent full hot swap support, only hot add and hot replacement are supported, but this is our The most used technology in hot swap, so the motherboard BIOS can overcome this problem. On the operating system side, it started to support plug-and-play from Windows 95, but support for hot plugging was very limited. Until NT 4.0 began, Microsoft began to notice that the NT operating system would be aimed at the server area, and this area was hot-plugged. Is a key technology, so the operating system has added full hot swap support, and this feature has been extended to the base NT technology Windows 2000/XP operating system, so as long as the operating system using NT4.0 above, hot Plug and play operating systems provide complete support. In terms of driving, the current Windows NT, Novell Netware, and SCO UNIX drivers all incorporate hot-swap functionality. As long as the drivers for the above operating systems are selected, the last element of hot-plugging is available.

In general, a complete hot-plug system includes hardware for hot-pluggable systems, hot-pluggable software and operating systems, hot-pluggable device drivers, and hot-pluggable user interfaces.

We know that in ordinary computers, USB (Universal Serial Bus) interface devices and IEEE 1394 interface devices can all be hot-swapped. The components that can be hot-swapped in servers are hard disks, CPUs, memory, and power supplies. , fans, PCI adapters, network cards, etc. When buying a server, be sure to note which components are hot-swappable, which is important for future work.