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Hewlett-Packard Disk-Arrays: HASS (top) and NIKE (OEM'd Data General SCSI Clariion)

EMC CLARiiON CX500 (Cover removed on one Shelf)

EMC Symmetrix DMX1000

A disk array is an enterprise storage system which contains multiple disk drives. It is differentiated from a disk enclosure in that an array has cache and intelligence so that it can perform functions like RAID and virtualization. Typically disk arrays provide some level of redundancy by use of mirrored or N+1 components (controllers, power supplies, fans, etc.) which are often hot-swappable.

Components of a typical disk array include

• Disk array controller
• Cache
• Disk enclosures
• Power supply

Typical disk arrays fall into five categories: NAS, Modular SAN arrays, Monolithic SAN arrays, Storage Virtualization and Utility SAN 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 trough 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
• Network Appliance Filer
• Sun StorageTek 5000 family

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 reffered as departmental. Examples:

• 3PAR Inc. 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
• Network Appliance FAS series Unified storage servers
• ONStor Pantera
• Sun StorageTek 6x40
• Xiotech Magnitude 3D

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 for mainframes in addition to Fibre Channel and iSCSI for open systems. 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)

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
• Network Appliance V-Series storage virtualization solutions

• 3PAR InServ Storage Servers
• Network Appliance FAS GX Series
• Pillar Data Systems Axiom

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