NORCO Intelligent Technology CO., LTD

A disk array is a disk storage system which contains multiple disk drives. It is differentiated from a disk enclosure, in that an array has cache memory and advanced functionality, like RAID and virtualization.

Components of a typical disk array include:

Disk array controllers
Cache memories
Disk enclosures
Power supplies
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 (SPOFs) are eliminated from the design. Additionally those components are often hot-swappable.

Typically, disk arrays are divided into five categories: NAS, Modular SAN arrays, Monolithic SAN arrays, Storage Virtualization and Utility SAN Arrays.

Contents Below
1 Network attached storage (NAS) arrays
2 Modular storage area network (SAN) arrays
3 Monolithic (enterprise) arrays
4 Storage virtualization
5 Utility Storage arrays:
 

Network attached storage (NAS) arrays
Network attached storage is a hard disk storage system on a network with its own LAN IP address. NAS arrays provide file-level access to storage through such protocols as CIFS and NFS. Examples:

3PAR and ONStor UtiliCat Unified Storage
EMC Celerra family
HP StorageWorks All-In-One Storage Systems
HP ProLiant' Storage Server
NetApp Filer
Sun StorageTek 5000 family

Modular storage area network (SAN) arrays
A SAN is a dedicated network, separate from LANs and WANs, that is generally used to connect numerous storage resources to one or many servers. SAN arrays provide block-level access to storage through SCSI-based protocols such as Fibre Channel and iSCSI. Modular storage system typcally consist of separate modules, which afford some level of scalability, and can be mounted in a standard rack cabinet. Modular storage systems are also sometimes referred as departmental. Examples:

3PAR InServ E-Class
EMC CLARiiON
Fujitsu ETERNUS 4000/3000 series storage arrays
HP Storageworks EVA family products
Hitachi Thunder family products
IBM DS4000/FAStT family of storage servers
IBM DS6000 series storage servers
Arena Maxtronic Janus Fibre Channel and iSCSI RAID systems
Infortrend EonStor/EonRAID family
NetApp FAS series Unified storage servers
ONStor Pantera
Sun StorageTek 6x40
Xiotech Magnitude 3D

Monolithic (enterprise) arrays
Although this is not a strict definition, the array is considered monolithic when even basic configuration is physically too large to fit into a standard rack cabinet. These arrays are suited for large-scale environments. Often Enterprise storage systems provide ESCON and FICON protocols for mainframes in addition to Fibre Channel and iSCSI for open systems SANs. Examples:

EMC Symmetrix
Fujitsu ETERNUS 8000/6000 series storage arrays
Hitachi Lightning and TagmaStore USP family products
HP XP
IBM Enterprise Storage Server (ESS)
IBM DS8000 series of storage servers
Infortrend EonStor / EonRAID family
Sun StorEdge 99xx (9970, 9980, 9985, 9990)

[edit] Storage virtualization
Intelligent SAN or Storage Servers (Software that adds disk controller functionality to standard server hardware platforms). Hardware independent software that typically runs as a control program on top of a standard OS platform (Windows, Linux, etc.):

DataCore Software Corporation SANsymphony and SANmelody Storage Server Virtualization Software
Falconstor IPStor Software
IBM SAN Volume Controller
NetApp V-Series storage virtualization solutions
RELDATA Unified Storage Gateway Appliance
EMC inVista