1.  Direct Attached Storage (DAS): is a traditional mass storage system that is either within or connected directly to a server, without a storage network in between. 


2.  Network Attached Storage (NAS): is mass storage attached to a computer which other computers (typically PCs) can access at file level over a network. 


3.  Storage Area Network (SAN): 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 to the operating system.  A SAN typically has its own network of storage devices that are generally not accessible through the local area network by other devices.  The cost and complexity of SANs has dropped in recent years to levels allowing wider adoption across both enterprise and small to medium sized business environments. 


The strength of a SAN over DAS and NAS: 

A Storage Area Network (SAN) is a dedicated network that provides access to consolidated, block level data storage, and helps you:


Eliminate Sprawl and maximise Utilisation

  • Handle all your storage needs with a single storage architecture – Eliminate individual DAS, NAS and file server silos
  • Optimise storage efficiency – maximise utilisation
  • Regain control over budget – Reduce administration

Reduce Overhead

  • Consolidate and automate administration – Infrastructure, storage, application, and data
  • Speed time to deployment – Deploy in minutes, not hours or days
  • Integrate with existing Windows management – Spend time on productive tasks

Reduce disruptions - Provision in minutes rather than days

  • Near-instant backups of all data – Eliminate backup windows and application downtime
  • Application-aware backup to produce consistent backups – Exchange, SQL Servers, SharePoint and Virtualisation
  • Simple restores – View previous backups and restore individual files and single mailboxes


Vendors and Products

  • NetApp – FAS 2020, FAS 2040, FAS 2060
  • HP – 2000, 4500