I.          INTRODUCTION

The Network Attached Storage (NAS) server is a specialized data delivery appliance designed specifically for performance, low cost of ownership, and reliability.

The SPANStor NAS file server comprises industry standard server hardware, specialized software and standard storage sub-systems that have been tailored to send data very quickly across the network, supplementing an organization's existing network server.

The emergence of NAS appliances for the storage marketplace is analogous to the development of network routers.  Originally, customers used a DEC VAX, Sun workstation, or IBM System/38 running routing software with a network interface card installed to provide network routing services.  Cisco and Synoptics recognized that a dedicated routing appliance would provide superior value and introduced products specifically designed to provide routing services.

Performance for routers sharply increased, system administration went way down, and reliability increased.  NAS appliances provide similar benefits for data storage access in the information infrastructure.  Explosive data growth has created problems of accessibility, manageability, and reliability for the Information Technology manager.  

II.                STREAMLINED ARCHITECTURE

Network Attached Storage 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, says Greg Garry, server analyst for Dataquest, a market research unit of Gartner Group Inc.  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, many NAS systems are still widely referred to as NFS servers, even though products like SPANStor support multiple protocols including Microsoft's Windows SMB/CIFS Common Internet File system.

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.

Network Storage Solutions, Inc. was started in October of 1996 with the management led buyout of the assets of industry pioneer Symmetrical Technologies, Inc, who began shipping network attached Optical storage devices in 1990.  NSS introduced the latest generation of SPANStor network attached RAID and disk products in May of 1998.  The SPANStor line of NAS devices provides unmatched speed, scalability, reliability, and ease of management.

NSS Network Attached SPANStor RAID offers many benefits over other disk storage subsystems including:

·         Lower maintenance costs

·         Faster data response times and application speeds

·         Higher Availability and Reliability

·         Y2K compliance

·         Enhanced Migration of existing data

·         Scalability

II.                STORAGE ARCHITECTURES

Traditionally, host servers attached to disk resources using direct connected SCSI connections.  As servers data loads and volumes increased, and server processing capacity increased, data I/O became a limiting factor in system performance.  Additionally, as the complexity of these systems increased, management costs and total cost of ownership climbed dramatically.

As direct connected systems grow in terms of capacity and the number of files stored, problems with performance and reliability grow significantly.  SPANStor NAS systems solve these problems by accelerating I/O and reducing data response times, in a simple data appliance model that is simple to install and manage.

The problems of increasing capacity, heterogeneous system access, manageability, and performance led to the development of the Storage Networking industry.  The Storage Networking industry includes both the Storage Area Network (SAN) and Network Attached Storage (NAS) product manufacturers.  SAN technology today is being driven by the various Fibre Channel manufacturers and includes both Fibre Channel Arbitrated Loop and Fabric Switched technologies.  SAN adoption has been hampered by vendor incompatibilities due to a loose specification, and a lack of standard access methods to allow sharing of data across platforms.  SAN architectures and products are designed to address the need for higher bandwidth connections between servers and storage nodes, with support for gigabit transfer rates.  Most SAN vendors today can support data transfer rates of 60 to 80 megabytes per second. 

 
However, SAN solutions address only a portion of the data I/O problem.  The overriding factor for most applications is not bandwidth, but response times.  Efficient data delivery to the client or application sitting on the network in the terms of quick responses to data requests is much more important to most common business applications than streaming data rates (bandwidth).  The Fibre Channel storage industry is responding to two major customer desires, the need for additional performance (bandwidth), and the ability to physically locate storage at a distance from the host server.  SPANStor Network Attached Storage provides an efficient, reliable, solution to both these requirements today, using standards based hardware and software.  

SPANStor network attached storage servers eliminate the server as a data bottleneck, delivering fast, and reliable and scaleable data access.   The SPANStor-GT product provides a highly scaleable data server that installs easily and integrates into existing information infrastructures.  Each SPANStor-GT supports up to four Network Processors (NPs), running on standard Intel Pentium-II hardware, in a single 19-inch rack mount chassis.  Each NP operates autonomously, providing linear scalability, high performance, and reliable data access.    Supporting NFS, SMB/CIFS, and HTTP protocols, the SPANStor-GT can be accessed by both UNIX and Windows clients concurrently.  Each NP can manage over a Terabyte of data supporting multiple Ultra Wide SCSI connections at speeds of 80 megabytes per second per SCSI interface.

 

As the number of Internet users and publishers grows, the demand for data-rich multimedia information is growing exponentially.  Rapid data access is key to the Internets Information Infrastructure.  Traditional measures of performance like storage bandwidth or throughput are rendered obsolete in an age where network clients require rapid data response times.  Increased demand stresses and overloads the traditional servers that are directly connected to storage resources, resulting in sluggish and erratic performance.  Network attaching storage with SPANStor provides the fast data response times demanded by the changing Internet Information Infrastructure.  Data response times have become the key storage metric in the Internet Information Infrastructure, and SPANStor products deliver high performance with exceptional response times.

Network attaching 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, which keeps the 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 of the tape transport, which 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 Quadratec.