---

Storage Area Networks

The proliferation of digital content across organizations in virtually every industry is causing storage needs to grow exponentially. In some industries, such as video processing and biotechnology, storage needs double every year. Three basic types of architectures have evolved to meet these growing storage needs:

• Direct-attached storage (DAS). A DAS solution consists of disk drives or storage systems connected directly to a server or workstation. Typically, the storage system is connected to a PCI card in the host server or workstation through a Fibre Channel interface. The server formats the DAS using a compatible disk file system, such as UFS or HFS+. It shares the storage with other computers over Ethernet using a network file sharing protocol, such as AFP, SMB, CIFS, or NFS.

• Network-attached storage (NAS). A NAS is a specialized storage device that connects to a local area network and shares files with clients using network file sharing protocols, such as AFP, SMB, CIFS, or NFS. True NAS devices use a specialized server operating system having limited functionality.

• Storage Area Network (SAN). A SAN is a network whose primary purpose is to connect (typically over Fibre Channel) multiple storage devices with multiple computers. Unlike a NAS, which uses network file sharing protocols to deliver stored data to network clients, a SAN connects multiple clients directly to the storage network through Fibre Channel switch. Data traverses the SAN using a high-speed SCSI data transfer protocol. A SAN pools storage resources by creating a network of physical storage devices that can be managed as a single virtual storage entity. A SAN centralizes storage management, which simplifies administration and allows storage resources to be used more efficiently.

All three storage architectures benefit from continual improvements in the size and performance of disk subsystems. However, only SANs can scale to meet the capacity and performance demands of users in the design and print, video, and biotechnology industries. SAN solutions streamline access to shared storage, simplifying workgroup collaboration and improving workflow productivity. SAN technology also increases the flexibility and scalability of storage deployments, making it easier for administrators to respond to growing capacity and performance requirements.

---