An external drive enclosure is the physical case that houses and powers a hard drive.
Enclosures, which can be purchased separately, contain the electronics and interfaces that allow a hard drive to connect to a computer. External hard drive enclosures may also be called disk enclosures or disk caddies.
In small business and home use, external drive enclosures can be useful for data recovery. Many times when a hard drive fails and the data it contains seems to be inaccessible, it is actually the electronics or connection points in the external drive enclosure that no longer work properly. Swapping the hard drive out to a different hard drive enclosure may be the only thing that's necessary for the data to be accessed again. Small business and home users can also use external drive enclosure to increase storage capacity by turning working hard drives from older desktop computers or laptops into external hard drives.
When purchasing external hard drive enclosures for small business or home use, the customer should look for a case that is compatible with the original drive's operating system and disk drive size.
In the enterprise, multi-bay external hard drive enclosures can be used to cluster hard drives for network-attached storage (NAS) and storage area networks (SANs) and RAID. Multi-bay drive enclosures typically have may built-in cooling fans.