Hot Swapping: What it is, how it works, and other frequently asked questions

Hot swapping is the act of replacing components of a device while the device is powered on, with no need to shut down or restart. Eligible components are referred to as hot-swappable. The term was popularized in the 1990s and hot swapping is now the standard for many types of devices.

A brief aside: what isn’t hot swapping?

• The “swap” refers specifically to removing a part and replacing it with a new or different one. Connecting only a new part without disconnecting an existing one is known as hot insertion or hot plugging.
• With many devices, powering down is required to exchange components, especially ones essential to its function, such as a power source or data drive. The process of powering down to disconnect and reconnect is called, as you might guess, cold swapping. Cold swapping is required in many cases not only for the safety of the data and device, but also that of the user.

Hot swapping is possible in many cases because the swapped device is not essential to the device’s function. Operation can continue unimpeded when a tertiary accessory, one that doesn’t affect most functions or data, is removed or replaced.

In other cases, where the component being swapped is core to the function of the device, such as a hard drive, hot swapping is made possible by the creation of duplicate or “dummy” data. By mirroring the content or function of the hard drive, the device can operate for a brief period of time by using its copy of the drive’s actions until that drive is physically replaced.

Another way hot swapping is possible is simply from the device having multiple bays or insertion points for components. When more than one of a type of component is inserted — a battery, for instance — the device can rely on just one of them while the redundant one(s) are replaced.

Common hot-swappable components

These types of devices are usually hot-swappable in consumer and commercial devices alike.

Audio devices

Think of any accessory you might use with a 3.5mm audio jack cable. Speakers, microphones, headphones, and headsets can all plug in or unplug without interfering with your device’s operation.

USB devices

This category encompasses all kinds of devices that use a USB connection — from USB-A to Micro- and Mini-USB. Some examples may include a storage flash drive, a webcam, and most keyboards.

Network cables

Hookups to Ethernet and phone modem cables are both examples of network connections that may be established without powering down the attached device.

Less common hot-swappable components

These cases may be more commonplace in industrial or medical technology, but are not always readily available in consumer-grade products.

Battery

A device with a rechargeable battery can last for a limited time off of its charger but removing its internal battery would immediately power it down, or worse — damage the boards and even put you in danger of electrical shock. Similarly, an average battery-powered consumer device, such as a TV remote with AA batteries, will cease functioning when even one of the batteries is removed. Even wired products, such as a kitchen blender plugged into the wall, cannot operate without a constant connection to their power supply.

To combat these issues, a device with hot-swappable batteries will contain multiple bays for batteries. In this case, keeping the device powered is as simple as adding a charged battery to a separate bay before removing the old one to charge.

Some smaller devices, such as some tablets, will have a small non-removeable reserve battery that allows the device to sustain itself briefly while the user exchanges the hot-swappable batteries.

Hard drive

Many drives can be hot-swappable, including even internal and external hard drives. A computer relies on duplicate copies of data created by the hard drive to continue operating while the drive is being replaced, preventing loss or corruption of data.