A disk array is a disk storage

Disk storage

Disk storage or disc storage is a general category of storage mechanisms, in which data are digitally recorded by various electronic, magnetic, optical, or mechanical methods on a surface layer deposited of one or more planar, round and rotating disks...

 system which contains multiple disk drives. It is differentiated from a disk enclosure

Disk enclosure

A disk enclosure is essentially a specialized chassis designed to hold and power disk drives while providing a mechanism to allow them to communicate to one or more separate computers. Drive enclosures provide power to the drives therein and convert the data sent across their native data bus into a...

, in that an array has cache

Cache

In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...

 memory and advanced functionality, like RAID and virtualization

Storage Virtualization

Storage virtualization or storage virtualisation is a concept and term used within computer science. Specifically, storage systems may use virtualization concepts as a tool to enable better functionality and more advanced features within the storage system.Broadly speaking, a 'storage system' is...

.

Components of a typical disk array include:

• Disk array controller
  Disk array controller
  A disk array controller is a device which manages the physical disk drives and presents them to the computer as logical units. It almost always implements hardware RAID, thus it is sometimes referred to as RAID controller. It also often provides additional disk cache.A disk array controller name is...
  
  s
• Cache
  Cache
  In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
  
   memories
• Disk enclosure
  Disk enclosure
  A disk enclosure is essentially a specialized chassis designed to hold and power disk drives while providing a mechanism to allow them to communicate to one or more separate computers. Drive enclosures provide power to the drives therein and convert the data sent across their native data bus into a...
  
  s
• Power supplies
  Power supply
  A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
  
  

Typically a disk array provides increased availability, resiliency and maintainability by using additional, redundant components (controllers, power supplies, fans, etc.), often up to the point when all single points of failure

Single point of failure

A single point of failure is a part of a system that, if it fails, will stop the entire system from working. They are undesirable in any system with a goal of high availability or reliability, be it a business practice, software application, or other industrial system.-Overview:Systems can be made...

 (SPOFs) are eliminated from the design. Additionally those components are often hot-swappable.

Typically, disk arrays are divided into categories:

• Network attached storage (NAS) arrays
• storage area network
  Storage area network
  A storage area network is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices...
  
   (SAN) arrays:
  • Modular SAN arrays
  • Monolithic SAN arrays
  • Utility Storage Arrays
• Storage virtualization
  Storage Virtualization
  Storage virtualization or storage virtualisation is a concept and term used within computer science. Specifically, storage systems may use virtualization concepts as a tool to enable better functionality and more advanced features within the storage system.Broadly speaking, a 'storage system' is...