22-09-2008, 10:29 AM
Definition
Information Technology (IT) departments are looking for cost-effective storage solutions that can offer performance, scalability, and reliability. As users on the network increase and the amounts of data generated multiply, the need for an optimized storage solution becomes essential. Network Attached Storage (NAS) is becoming a critical technology in this environment.
The benefit of NAS over the older Direct Attached Storage (DAS) technology is that it separates servers and storage, resulting in reduced costs and easier implementation. As the name implies, NAS attaches directly to the LAN, providing direct access to the file system and disk storage. Unlike DAS, the application layer no longer resides on the NAS platform, but on the client itself. This frees the NAS processor from functions that would ultimately slow down its ability to provide fast responses to data requests.
In addition, this architecture gives NAS the ability to service both Network File System (NFS) and Common Internet File System (CIFS) clients. As shown in the figure below, this allows the IT manager to provide a single shared storage solution that can simultaneously support both Windows*-and UNIX*-based clients and servers. In fact, a NAS system equipped with the right file system software can support clients based on any operating system.
NAS is typically implemented as a network appliance, requiring a small form factor (both real estate and height) as well as ease of use. NAS is a solution that meets the ever-demanding needs of today's networked storage market
NETWORK STORAGE CONCEPTS
In basic terms, network storage is simply about storing data using a method by which it can be made available to clients on the network. Over the years, the storage of data has evolved through various phases. This evolution has been driven partly by the changing ways in which we use technology, and in part by the exponential increase in the volume of data we need to store. It has also been driven by new technologies, which allow us to store and manage data in a more effective manner.
In the days of mainframes, data was stored physically separate from the actual processing unit, but was still only accessible through the processing units. As PC based servers became more commonplace, storage devices went 'inside the box' or in external boxes that were connected directly to the system. Each of these approaches was valid in its time, but as our need to store increasing volumes of data and our need to make it more accessible grew, other alternatives were needed. Enter network storage.
Network storage is a generic term used to describe network based data storage, but there are many technologies within it which all go to make the magic happen. Here is a rundown of some of the basic terminology that you might happen across when reading about network storage.
Direct Attached Storage (DAS)
Direct attached storage is the term used to describe a storage device that is directly attached to a host system. The simplest example of DAS is the internal hard drive of a server computer, though storage devices housed in an external box come under this banner as well. DAS is still, by far, the most common method of storing data for computer systems. Over the years, though, new technologies have emerged which work, if you'll excuse the pun, out of the box.
Network Attached Storage (NAS)
Network Attached Storage, or NAS, is a data storage mechanism that uses special devices connected directly to the network media. These devices are assigned an IP address and can then be accessed by clients via a server that acts as a gateway to the data, or in some cases allows the device to be accessed directly by the clients without an intermediary.
