What Is NAS? Network Attached Storage

Network Attached Storage (NAS) is by far the easiest type of storage networking to implement. The simplest way to think of NAS is as a specialized kind of file server. Anyone who has used a server as a repository for user files should be able to easily grasp the concept of NAS. Instead of writing a file to the C drive on a local desktop, it is written to another drive – perhaps the N drive – which means the files are saved directly onto the NAS box (also known as a filer, or NAS filer).

While a file server has a limited supply of storage, NAS storage can provide you with terabytes (TB) of space that is instantly accessible to anyone over a standard Ethernet connection. Compared to a general-purpose server serving files, NAS offers faster data access and easier administration. It also offers:

· A simpler configuration Think of it as having to access each individual server to find files, versus having all files in one large NAS pool with a global namespace. This enables anyone to find and open files rapidly.

· Data manageability NAS has historically been the preferred means of network storage where data manageability was a higher priority than raw performance. Data manageability was particularly important for those with large files or large numbers of files. However, the advent of SSDs now enables NAS to deliver levels of performance traditionally only available from block-based Storage Area Network (SAN) systems.

·  Less expensive than SAN NAS provides a cheaper network storage system than a SAN. According to IDC, file-based data storage accounts for two thirds of the total storage capacity shipped each year. Part of the reason for this is simplicity and the other is cost. By deploying NAS, organizations avoid the need to purchase expensive storage arrays, an extensive Fibre Channel (FC) fabric and import SAN specialists to manage what is a highly technical infrastructure.

The simplicity associated with NAS storage, however, has changed somewhat in recent years. Modern day enterprise NAS tools now come prepackaged with all manner of bells and whistles. This might include dynamic point-in-time snapshots, replication, thin provisioning, deduplication and compression as well as faster speeds and larger capacities.

networked attached storage

Networked attached storage is a fundamental element of data storage infrastructure.

NAS: 3 Key Considerations

Realize that when deploying NAS, your business must weigh three core considerations.

·  Security From a security standpoint, NAS devices either provide file system security capabilities of their own, or allow user databases to be used for authentication purposes. Further NAS benefits include devices being located close to the users thereby reducing network traffic. Another advantage of NAS is that it offers platform independent access. For instance, as many environments now use more than one operating system, enterprise NAS provides a mechanism that allows users to access data irrespective of what OS is used to authorize them on the network. NAS, though, is not faster than DAS. Many times, the speed of the network impedes data retrieval. Even if NAS is armed with SSDs, it is unlikely to outperform a server using flash.

·  NAS is also cheap Starting from just a few hundred dollars, NAS is available as free-standing or rack-mounted units that can accommodate storage devices of all types and all capacities. Many NAS devices also incorporate technologies such as RAID and provide UPS capabilities as well. When you need network storage, but you don’t want to get involved with the complexity and expense of a SAN, NAS is the way to go. All it takes to start can be as simple as plugging a NAS box into the network and away you go.

·  The database question NAS, though, doesn’t do particularly well with databases. And large enterprises or those with the need for the highest possible network performance should probably stick to a SAN. But the firm line of separation that used to exist between NAS and SAN is changing due to convergence. Many recent NAS offerings support the NAS protocols (NFS, CIFS/SMB) and the SAN protocols (iSCSI, Fibre Channel) from a single piece of hardware.

Alternatives to NAS

Let’s look at how NAS measures up against Direct Attached Storage (DAS) and the SAN.

·  DAS is storage that is attached directly to a computer or server. Unlike the others systems, DAS isn’t part of a storage network. In a DAS configuration, storage devices such solid state drives (SSD) and hard drives are attached directly to the system through accessing them. It is called ‘direct’ as the connection between device and the server is typically achieved using a storage device interface such as Integrated Drive Electronics, or the Small Computer Systems Interface (SCSI). The storage devices are either physically inside the server to which they are attached or in external housings connected by a cable. DAS drawbacks include resource contention. The server hosting the data may be better employed crunching numbers or providing raw compute power than merely serving up files. There can also be a licensing issue. You need far more licenses with a lot of data on DAS than you would hosting them on some kind of network storage.

·  SAN is a form of network storage whereby multiple devices are connected to each other and to a server, or cluster of servers. They utilize special switches between devices, which make it possible them to communicate with each other on a network separate from routine Ethernet. This factor of isolation from other networks makes back-up much simpler and faster – the backup is not computing for bandwidth with other applications. SANs make use of either FC or iSCSI technology (iSCSI allows data to be transported to and from storage devices over an IP network). The SAN provides the highest performance type of storage network, However, if a SAN sprawls too widely, the enterprise may need to develop multiple SAN fabrics. SANs, too, are more complex than NAS and DAS. They are also more expensive.

In this article NAS vs. SAN, we discuss the fundamental differences and use cases between the two technologies.

·  Also be aware  SANs are separate networks dedicated to storage devices, while a NAS device is a storage subsystem that is connected to the network media. NAS, then, takes a more streamlined and dedicated approach to making data available to clients in a heterogeneous network. Their hardware components, software and firmware are tightly integrated and far more reliable than DAS. NAS devices operate independently of network servers and communicate directly with the client. In the event of a network server failure, clients will still be able to access files stored on a NAS storage device. NAS maintains its own file system and accommodates network protocols such as TCP/IP and IPX/SPX, and uses file access protocols such as SMB, CIFS, NCP, HTTP and NFS.

Real life applications for NAS

NAS has evolved tremendously since its early beginnings. Massively scalable, high performance file storage systems are now available to support intensive processing from a variety of applications. There are many examples and use cases:

·  An automotive services provider ingests several millions of image files every day. Streaming this amount of data to the cloud is a non-starter because of cloud latency. The provider uses massively scaled enterprise NAS to store the images and uses cloud caching to maintain pointers to the on-premise files.

·  A university digital library ingests huge volumes of raw data from oceanic, climate, and genomic studies all over the world. A high performance NAS system stores the data into a single namespace for analytics and scientific processing. These specialized single namespace NAS storage systems are custom-built using commodity hardware to store and process huge quantities of raw machine data. They are capable of storing billions to trillions of vastly differently sized files and linearly scale capacity and performance.

·  They easily support high-end applications such as rendering, microscopy, image processing, and 3-D animation.

·  NAS has been also been embraced by cloud providers such as Google, Microsoft and Amazon. They have incorporated NAS into their cloud storage architectures.

·  NAS incorporates far more analytics capabilities. Metadata analytics, for example, like those offered through data virtualization, are being packaged with NAS solutions to let users better search and utilize their data.

·  Machine learning is another area where NAS deployment is on the increase.

Open Source NAS storage

The open source community has adopted NAS in many diverse ways. Examples include:

·  Ceph (particular with the new Jewel release)

·  FreeNAS

·  OpenFiler

·  Red Hat Gluster

Red Hat Gluster, for example, can be employed to help enterprises build distributed NAS services either on bare metal, in virtualized and containerized environments or in the public cloud. Storage clusters can synchronize across long distances, and provide standard SMB and NFS interfaces for large numbers of simultaneous clients. This approach works well for rich media, archival, analytics, and generic file sharing workloads.

Overall, NAS usage is expanding in vertical markets and environments that require raw storage capacity and scalability, such as video surveillance, active archives, media asset management, video streaming, and post-production. Their workloads require a reliable and easy-to-manage NAS environment that can scale to their needs and support long-retention demands.

Overall, three markets appear to be emerging as bastions of NAS usage in the enterprise:

·  Traditional large-scale file repositories that can speak NFS and HTFS

·  Video surveillance and medical archiving 

·  File sharing for users with generic file share needs, including SMBs.

The Future of NAS

What the future of NAS? NAS is likely to continue in its role as a complement to block storage, where performance is not a big factor and ease of access is the major criteria. By utilizing the latest multi-core servers and flash, large-scale NAS deployments can offer even greater performance than ever. In any case, NAS is continuing to evolve and is likely to a major component of storage going forward. 

Drew Robb
Drew Robb
Drew Robb has been a full-time professional writer and editor for more than twenty years. He currently works freelance for a number of IT publications, including eSecurity Planet and CIO Insight. He is also the editor-in-chief of an international engineering magazine.

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