Server Cabinets
A 19-inch rack is a standardized frame or enclosure for mounting multiple equipment modules. Each module has a front panel that is 19 inches (480 mm) wide, including edges or ears that protrude on each side which allow the module to be fastened to the rack frame with screws.
Computer Mounting in the Server Cabinet
Computer servers designed for rack-mounting often include a number of extra features to make the server easy to use in the rack:
The sliding rails can lock in the extended position to prevent the equipment from moving when extended out from the rack into the service position.
The server often has locking pins on the sides that just drop into slots on the extended rail assembly. This permits a very easy server installation and removal since there is no need for the server to be held in midair while someone fastens each rail to the sides of the server with screws.
The rack-mount hardware often includes a folding cable tray behind the server, so that the cables are held into a neat and tidy folded channel when inside the rack, and unfolds out into a long strip when pulled out of the rack, allowing the server to continue to be plugged in and operating normally even while fully extended and hanging in midair in front of the rack. This cable tray also helps prevent an often huge cable tangle from forming at the rear of the rack, as unbound cables from upper equipment drape down onto equipment below.
Rack-optimized servers often include an indicator light on the front and rear of the rack to help identify a machine needing attention. Since there can be up to 45 1U servers in a single rack, it can be difficult to determine exactly which machine is having a problem when at the rear of the rack.
A handle may be provided at the rear of the server rails, to help pull or push the server without having to pull on the cables.
When there are a large number of computers in a single rack, it is impractical for each one to have its own separate keyboard, mouse, and monitor. Instead, a controlling device known as a KVM switch is used to share a single keyboard/video/mouse set amongst many different computers.
Since the mounting hole arrangement is vertically symmetric, it is possible to mount rack-mountable equipment upside-down. However, not all equipment is suitable for this type of mounting. For instance, most optical disc players will not work upside-down because the driving motor mechanism does not grip the disc.