technical document ref# san_nascom.html
issue date: 1 Jul 2002
by Billy Ko - technical consultant

Network Attached Storage is designed to separate storage resources from network and application servers, in order to simplify storage management and improve the reliability, performance and efficiency of the network, thus increasing the overall productivity of the organization.

Network Attached Storage servers are self-contained, intelligent devices that attach directly to your existing LAN.  A file system is located and managed on the NAS device and data is transferred to clients over industry standard network protocols (TCP/IP or IPX) using industry standard file sharing protocols (SMB/CIFS, NCP, NFS, AFP or HTTP). This intelligence on the NAS device enables true data sharing among heterogeneous network clients.

Benefits of Network Attached Storage

    Streamlined Architecture
    Network Attached Storage Appliances have a streamlined architecture designed for one function, to serve data files to clients in heterogeneous network environments.  Powered by an operating system optimized for file I/O activity, file serving performance is greater than that of a general purpose server, which is designed to perform a multitude of functions. A modern multi-tasking operating system can have 6 million lines of code in order to provide multiple general-purpose functions. A file-serving specific NAS operating system is a fraction of the size and runs much faster and more efficiently. The result is improved data access times for network clients.

    Reduced Server I/O Bottlenecks
    The largest source of network and application server degradation is file service.  Carnegie Mellon University studies show that the server processor spends on the average 25% of its time serving file I/O requests. This percentage increases as simultaneous requests increase. Separating storage from the server reduces the file serving activity and I/O bottlenecks and increases server bandwidth. CPU cycles can then be dedicated to handling application requests, resulting in improved client response time.

    Increased Reliability and Data Availability
    The architecture of a thinserver appliance is designed around a specific function. All components, both hardware and firmware, are tightly integrated to perform that single function.  This “closed box” architecture provides for extremely high reliability.

    According to Dataquest over 60% of server failures are caused by storage related problems. Network downtime resulting from server failure costs organizations thousands of dollars per hour.  Separating storage resources from the server decreases both the number of components and the amount of file I/O activity. This reduces the probability of server downtime and increases the reliability of the network and application servers.  A more reliable and efficient network saves your organization time and money.

    Most networks do experience server downtime at some point, whether it’s for planned maintenance or due to unexpected crashes or outages. Because NAS Servers operate independent of network servers and communicate directly with the client, files remain available in the event of network server downtime. 

    Efficient Allocation and Use of Resources
    Network Attached Storage provides a common pool of storage that can be shared by multiple servers and clients, regardless of their file system or operating system.  This enables you to efficiently allocate storage, and alleviates the problem of one server running out of storage while another server might have more than needed.

    NAS enables you to locate storage where it's needed on the network and provide clients with direct, server independent communication to storage resources. Localizing file I/O traffic provides for a more efficient use of network resources.

    A NAS appliance connects directly to your existing LAN and transfers data over standard network access protocols (TCP/IP or IPX) using standard file sharing protocols (SMB/CIFS, NCP, NFS, FTP or HTTP). No additional software or client licenses are required for clients to access storage. This enables you to implement a storage solution and leverage your existing network investments.

    The traditional methods of adding storage are too cumbersome for today's network environments. Network Attached Storage enables you to add storage anywhere on your network in minutes simply by plugging in a network cable, applying power and configuring a few settings.  There is no server re-configuration and no network downtime.  And this can all be done during normal working hours.

    Management of NAS Appliances can be performed from anywhere on your network or over the Internet using a standard web browser or alternative management tools. Product enhancements and problem fixes are performed with a simple 3-minute flash upgrade.  A thinserver appliance is so simple, there is no need to understand or learn a complex operating system and anyone can administer one.

    Increased Productivity
    NAS Appliances provide increased productivity for your whole organization. Network clients benefit from the ability to share storage resources with clients from another network. They also benefit from reduced data access times and improved application server response times. And in the unlikely event of network server downtime, network clients can still access work files, therefore maintaining their productivity.  Network administrators, on the other hand, enjoy the luxury of simple installation, management and less storage related problems.

    Lower Total Cost of Ownership
    Although disk drives costs have dropped drastically in the last year, the average company spends roughly $3.50 per megabyte each year, in administrative and lost productivity costs, to manage its current storage.  Network Attached Storage, with its many benefits, features a lower total cost of ownership than other methods of adding storage to your network.

Network Attached Storage Appliances vs. General Purpose Servers

A NAS appliance is characterized by a streamlined architecture designed and optimized for performing one function - data delivery.  This "closed box" approach results in more efficient performance, higher reliability, easier installation, management and use, and lower total cost of ownership as compared to a general-purpose server.


NAS Appliance

General Purpose Server


Operating system and hardware platform designed and optimized to perform a specific function very efficiently

Low Overhead

Operating system and hardware platform designed for serving applications and multiple general-purpose functions

High Overhead

Reliability & Data Availability

Streamlined architecture with specialized OS results in high reliability and data availability

A greater number of non-embedded components and complex, general purpose software OS means a higher chance of failure and downtime


Simple administration of specialized operating system

High administration overhead of complex NOS system


Network operating system independent

Multi-protocol client support

Network operating system dependent

Client must meet the server’s interface and protocol requirements





Streamlined costs. All hardware and software components are for specific function - Data I/O

Unlimited Users - No license required

Unnecessary costs. More than the needed components for file services


Client licenses

Total Cost of Ownership



Network Attached Storage (NAS) vs. Storage Area Networking (SAN)

    Network Attached Storage (NAS)
    A NAS appliance is a self-contained, intelligent storage device that attaches directly to the LAN and transfers data over network protocols (TCP/IP or IPX) using industry standard file sharing protocols (SMB, CIFS, NCP,AFP, NFS, HTTP). Network clients communicate directly with the storage server

    Storage Area Network (SAN)
    A SAN is a discrete network of servers and storage devices (RAID, Tape Libraries, etc.) attached together via a high speed I/O interconnect, such as Fibre Channel. Data is transferred via serial I/O rather than network protocols, and raw data requests are made directly to disk and not over the LAN. All storage transactions are processed on a separate network with dedicated bandwidth for data.




Network Wires

TCP/IP or IPX over Ethernet, Fast Ethernet, Token Ring, FDDI & ATM

Fibre Channel


Industry standard file sharing protocols; SMB, CIFS, NCP, AFP, NFS & HTTP

Raw data requests directly to disk drive

File System

The file system is located at the storage

The file system is located at the application server

Data Sharing

True data sharing between heterogeneous clients because file system is at the storage side and data is transferred to client using industry standard file sharing protocols

Software required on all nodes on SAN in order for heterogeneous nodes to share files


Workgroup to Enterprise



Plug and Play into existing network

Difficult and expensive

Fibre Channel based hubs and switches to channel traffic; routers to interconnect data devices; and servers and software to link them all.


Based on industry standard technologies

Based on newer immature technologies