Network Attached Storage Overview

Network attached storage (NAS) has come a long way from the early 1990s when companies brought NAS optical devices to market. The NAS market includes products ranging from low-end workgroup servers with limited features and few expansion capabilities to enterprise solutions that are scalable, manageable, and expandable. NAS products have found their way into the enterprise as companies look for alternatives to costly and challenging to manage direct-attached storage (DAS). NAS products have also become the perfect complement to highly capable storage area networks (SAN). The integration of NAS and SAN has been a huge development in the networked storage world, offering customers flexible solutions that allow them to stretch their storage dollars.

The Network Attached Storage (NAS) server, appliance, or device is a specialized data delivery product designed specifically for performance, low cost of ownership, and reliability. NAS devices are designed to provide a safe, secure means of housing files and other data in an easy to access and manage storage subsystem.

Streamlined Architecture
NAS servers address this problem by streamlining file server configurations and operations, stripping away everything that is not needed to store and distribute data. Typically, a general file server would involve a reduced instruction-set computing (RISC) chip-based server for Unix systems or an Intel Corp. PC-based server for Windows NT networks, with a disk drive storage array attached to the server.

Much of the computing power of general servers is wasted in file server operations, which makes it a very poor investment. According to a study conducted by Carnegie Mellon University most servers require 25% of available CPU cycles for file I/O. Being a file server has everything to do with the [input/output] data path, not computing power. The general-purpose flexibility of such servers extends all the way down to the operating system. A modern multitasking operating system can have 6 million lines of code, and it provides many functions that are not needed for file services. A stripped-down file-serving-specific program is a fraction of the size and runs much faster.

Networked file systems originally gained popularity after Sun Microsystems' Network File System (NFS) was placed in the public domain and most UNIX-based systems adopted the protocol for networked file access. Today, in some circles, NAS systems may still be referred to as NFS servers, even though products like NSS Thunderbolt support multiple protocols including Microsoft's Windows SMB/CIFS Common Internet File system, HTTP, and ftp.

Keeping files on a server in a format that is accessible by different users on different types of computers lets users share data and integrate various types of computers on a network. This is a key benefit for NAS systems. Because NAS systems use open, industry standard protocols, dissimilar clients running various operating systems can access the same data. So it does not matter if there are Windows users or UNIX users on the network. Both can utilize the NAS device safely and securely.

NAS products provide many benefits over other disk storage subsystems. Benefits include:

• Lower maintenance costs
• Faster data response times and application speeds
• Higher Availability and Reliability
• Y2K compliance
• Enhanced Migration of existing data
• Scalability

Network attached storage can reduce traffic on backbones by best locating data on virtual sub-nets closest to the user population that most accesses the data on a particular network processor. Backup times are reduced with local backups on the NAS appliance keeping backup data off the network by streaming data from the disk volumes to tape devices attached to the NAS server. This approach permits the tape devices to run at their streaming speed, avoiding the stop/ start cycles (shoe-shine) of the tape transport that greatly reduces throughput. SPANStor supports both a Native Backup mode and the Network Data Management Protocol (NDMP). NDMP enables the NAS appliance to fulfill backup and restore commands locally for high performance, yet operate under the control of a host based NDMP compliant backup program from vendors like Legato, Veritas, or Syncsort. For more information on NDMP visit the NDMP web site at URL http://www.ndmp.org.

In summary, NAS servers or appliances are designed to provide industry standard interfaces to information, in a fast, reliable, easy to manage device. Either as standalone storage solutions or as part of an integrated NAS-SAN solution they make a lot of sense for companies who are concerned about their data being safe, secure, and accessible.

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