The 19-inch part of a 19-inch server chassis refers to the width of the rack's front panel. Mounting equipment is included in this measurement. The height is denoted through another measurement called U, which is typically 1.75 inches high. This is a standard size for server components such as motherboards and hard drives. The 19-inch server chassis is also commonly used for audio equipment.
A Redundant power supply works best with server chassis that is set up for dual power supplies. It's important to keep redundant systems in place to support network equipment in the event of a power failure. The amount of space this equipment takes on a rack depends on the U measurement. A typical Rack Cabinets has 42U, so equipment can be added in a number of configurations. 1U to 4U is the typical size for most rack mounted equipment.
The mount points have a few features to be aware of. Some server-chassis can be attached with front and rear mounting, adding stability to its installation. The redundant power supply can also be mounted on the rack. Other options include a feature that prevents the rack from being pulled out all the way, but provides accessibility to the equipment as needed. The racks themselves also have securing mounts.