Some people confuse NAS with storage area networks (SANs); after all NAS is SAN spelled backwards. The technologies also share a number of common attributes. Both provide optimal consolidation, centralized data storage, and efficient file access. Both allow you to share storage among a number of hosts, support multiple different operating systems at the same time, and separate storage from the application server. In addition, both can provide high data availability and can ensure integrity with redundant components and redundant array of independent disks (RAID).

Figure 1. A basic configuration for a NAS filer on LAN.

Others may view NAS as competitive to SAN, when both can, in fact, work quite well in tandem. Their differences? NAS and SAN represent two different storage technologies and they attach to your network in very different places. NAS is a defined product that sits between your application server and your file system (see Figure 1). SAN is a defined architecture that sits between your file system and your underlying physical storage (see Figure 2). A SAN is its own network, connecting all storage and all servers. For these reasons, each lends itself to supporting the storage needs of different areas of your business.

Figure 2. A typical SAN configuration.

NAS: Think Network Users

NAS is network-centric. Typically used for client storage consolidation on a LAN, NAS is a preferred storage capacity solution for enabling clients to access files quickly and directly. This eliminates the bottlenecks users often encounter when accessing files from a general-purpose server.

NAS provides security and performs all file and storage services through standard network protocols, using TCP/IP for data transfer, Ethernet and Gigabit Ethernet for media access, and CIFS, http, and NFS for remote file service. In addition, NAS can serve both UNIX and Microsoft Windows users seamlessly, sharing the same data between the different architectures. For client users, NAS is the technology of choice for providing storage with unen-cumbered access to files.

Although NAS trades some performance for manageability and simplicity, it is by no means a lazy technology. Gigabit Ethernet allows NAS to scale to high performance and low latency, making it possible to support a myriad of clients through a single interface. Many NAS devices support multiple interfaces and can support multiple networks at the same time. As networks evolve, gain speed, and achieve latency (connection speed between nodes) that approaches locally attached latency, NAS will become a real option for applications that demand high performance.

SANs: Think Back-End/Computer Room Storage Needs

A SAN is data-centric - a network dedicated to storage of data. Unlike NAS, a SAN is separate from the traditional LAN or messaging network. Therefore, a SAN is able to avoid standard network traffic, which often inhibits performance. Fibre channel-based SANs further enhance performance and decrease latency by combining the advantages of I/O channels with a distinct, dedicated network.

SANs employ gateways, switches, and routers to facilitate data movement between heterogeneous server and storage environments. This allows you to bring both network connectivity and the potential for semi-remote storage (up to 10 km distances are feasible) to your storage management efforts. SAN architecture is optimal for transferring storage blocks. Inside the computer room, a SAN is often the preferred choice for addressing issues of bandwidth and data accessibility as well as for handling consolidations.

Due to their fundamentally different technologies and purposes, you need not choose between NAS and SAN. Either or both can be used to address your storage needs. In fact, in the future, the lines between the two may blur a bit according to Evaluator Group, Inc. analysts. For example, down the road you may choose to back up your NAS devices with your SAN, or attach your NAS devices directly to your SAN to allow immediate, non-bottlenecked access to storage.

For small office requirements, to large corporate data-centres, ITMS Ltd can provide a suitable storage solution for your business.

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