Network Attached Storage

PDF version of this report
You must have Adobe Acrobat reader to view, save, or print PDF files. The reader
is available for free

Network Attached Storage

by Faulkner Staff

Docid: 00017962

Publication Date: 2106

Report Type: TUTORIAL


Network attached storage (NAS) devices are self-contained appliances that
connect directly to a network without need for an external server.
Although market growth slowed as new technology made storage area networks
(SANs) more affordable, the NAS product class is still expanding. This
report looks at the technology, describes some representative products,
and points out appropriate applications for these inexpensive, robust, and
manageable devices.

Report Contents:

Executive Summary

[return to top of this

In the beginning, traditional servers were built to include sufficient
directly attached storage to serve their roles.

Related Faulkner Reports
Storage Area Networks Tutorial

If the server crashed or became overloaded by its file serving functions,
the networked clients suffered slowdowns or were unable to access their
data, preventing them from doing their work.

The idea behind network attached storage is to enable application servers
to better serve clients by moving most of their file serving functions to
dedicated devices specifically designed for that task. These devices
provide an inexpensive way for companies to add large amounts of storage
to their networks while minimizing additional management overhead and
providing almost infinite scalability.


[return to top of this

The NAS server is essentially a small, special-purpose server that is
optimized for file sharing.

Like traditional file servers, a NAS server follows the conventional
client/server design. A single hardware device, often referred to as a NAS
box or NAS head, acts as the interface between the NAS system and its
clients. These NAS devices require no monitor, keyboard, or mouse, and
they generally run an embedded OS (often Unix or Linux-based) rather than
a full-featured server operating system. In a NAS environment, clients
connect to shared drives, much as they would on a traditional server, but
without the overhead of the traditional server’s additional functionality.
A NAS server can store any data that appears in the form of files such as
e-mail, Web content, and remote system backups.

Some people confuse network attached storage (NAS) with storage area
networks (SANs). While both technologies allow customers to share storage
among multiple hosts, there are some not-so-subtle differences:

  • NAS – A NAS appliance is a self-contained,
    intelligent storage device that attaches directly to the LAN (local area
    network) and transfers data using standard network protocols such as
    TCP/IP, using industry-standard file-sharing protocols (such as SMB,
    CIFS, NCP, AFP, ftp, NFS, or HTTP).
  • SAN – A SAN is a discrete network of servers and
    storage devices (RAID, tape libraries) connected together via a
    high-speed I/O interconnect (such as Fibre Channel).

Figure 1 depicts a typical NAS configuration.

Figure 1. Typical NAS Deployment

Figure 1. Typical NAS Deployment

Source: Wikimedia

While the benefits of network attached storage include streamlined
architecture, improved resource allocation, and simpler management, the
real selling points are a reduction in I/O bottlenecks and increased data
availability, not to mention considerably lower pricetags than those
attached to SANs.

Reduced Server I/O Bottlenecks

Studies at Carnegie Mellon University show that a conventional server
processor spends (on average) 25 percent of its time handling file I/O
requests, a percentage that increases as the number of simultaneous
requests increase.

Separating the storage from the server reduces this activity, decreasing
I/O bottlenecks. CPU cycles which would normally be dedicated to
input/output functions are now free to process application requests,
improving both customer response time and user satisfaction.

Increased Data Availability

On average, more than 60 percent of server failures are caused by
storage-related problems, resulting in extensive – and expensive – network

Separating the storage from the server decreases the number of hardware
components and amount of file I/O activity. As a consequence, server
downtime is “down” and the reliability of network and application servers
is correspondingly up.

NAS Appliances vs. General Purpose Servers

The differences between a network attached storage server and a general
purpose server are summarized in Table 1.

Table 1. NAS Servers vs. General Purpose Servers

Server Attribute

NAS Appliance

General Purpose Server


The hardware and operating systems are
designed and optimized to perform a single function very

Supervisory overhead is low.

The hardware and operating systems are
designed to support application serving and multiple general
purpose functions.

Supervisory overhead is high.


The streamlined, i.e., simple, architecture
promotes high reliability.

The large number of non-embedded components
plus a complex operating system contribute to a higher
probability of failure.


The relatively simple operating system
requires less “care and feeding.”

The more complex network operating system
demands greater attention.


The server is network operating system
independent, supporting multiple client protocols.

The server is network operating system
dependent. Clients must accommodate the server’s interface and
protocol requirements.





“Transparent” to other application

Diverts resources from other application


All hardware and software components
facilitate a single function – data I/O. There are no
extraneous, i.e., non-data I/O, expenses.

The hardware and software support both data
I/O and non-data I/O functions.

Total Cost of Ownership (TCO)



Source: Advanced
Media Services

The market for network attached storage is still rising steadily,
outpacing SAN revenue growth. Industry analysts predict that NAS sales
will continue to grow, but pricing battles will prevent the capacity
increase from being fully reflected in revenue figures. Analysts say that
network-attached storage (the combination of SAN and NAS) has far
outstripped direct-attached storage in the marketplace.

The major manufacturers of enterprise-class NAS appliances include firms
such as NetApp (formerly Network Appliance), EMC, Hitachi Data Systems,
Dell, IBM and HP. These manufacturers offer a range of systems spanning
the needs of small to large enterprise clients. For example, NetApp offers
its “AFF A-Series” line, which supports from 35 to 702.7 PB of raw storage
space, with the option to stack units in a rack server configuration for even
more storage.1

Current View

[return to top of this

Networked storage of some description (SAN or NAS) has gained favor over
direct-attached storage thanks to the ability to dynamically reallocate
resources as required by workload. In general, however, network attached
storage appliances have not provided the full end-to-end data integrity
required for critical database operations. Oracle itself has acknowledged
that managing databases using new and dynamic storage technologies, such
as network attached storage, storage area networks, and Fibre Channel, can
be “challenging”. NAS vendors, however, are constantly enhancing the
technology, to the point that some will now support databases or e-mail
data stores, and virtualization technology is addressing scalability and
provisioning issues. In addition, new high capacity disk drives allow NAS
appliances to contain more storage per box.

Since NAS devices are directly attached to a network and many do not
offer any other direct connections such as SCSI ports, backup can be an
issue. Software such as CA’s ArcServe and Symantec NetBackup do directly
access NAS devices that support NDMP (Network Data Management Protocol),
and most programs will allow backup of devices that are mounted as share
points on workstations or servers. Some NAS devices now offer their own
mirroring capabilities and offer RAID to enhance reliability. Throughput,
however, can become a major problem in these cases, although today’s
high-end systems offer everything from Fibre Channel to gigabit Ethernet

Vendors have been successfully addressing these issues and growth in the
higher-end segment of the NAS market continues. NAS devices are even being
included in SAN infrastructures.

As high-capacity disk drives have become less expensive, a number of
vendors such as Seagate and Buffalo began
offering NAS appliances for home and small business networks to allow
consumers and SMBs to easily share their digital media, further expanding
the market.


[return to top of this

Contrary to predictions that it would be supplanted by the SAN product
category, the NAS
market is alive and well. Growth continues at a steady pace, especially in
entry-and mid-level products, and NAS appliances are finding homes in
organizations of all sizes, as well as on home networks. Vendors continue
to increase capacity and address shortcomings such as difficulties with
backups, and customers continue to snap up these cost-effective, easy to
manage storage devices to provide accessible file space, especially for
workgroups and remote offices.

According to MarketsandMarkets, the global NAS market is estimated to
grow from 23.2 billion USD in 2020 to 48.0 billion USD by 2025 with a CAGR
of 15.7%. The firm reports that the increasing use of smartphones,
laptops, and tablets resulting in the generation of large volumes of data
and the adoption of 4G and 5G technologies are attributing to the growth
in this market.2

IBM offers devices that unify SAN and NAS and it has introduced an
innovative twist into the market: a NAS gateway that gives NAS
capabilities to standard storage devices. EMC, too, is taking this
approach, as is disk vendor Seagate which has produced docks that allow
its standalone desktop external disks and portable units to become NAS
appliances. This provides additional scope for the product category.


[return to top of this

Network attached storage is ideal for small to medium-sized businesses,
owing to three factors:

  • The simplicity of installation and maintenance.
  • The support for cross-platform file sharing.
  • Cost.

These factors also make the technology attractive to enterprises in need
of workgroup or special-purpose storage. More recently, NAS devices have
also been incorporated into enterprise SANs, where any management
deficiencies are compensated for by the SAN.


Today’s NAS systems are “plug and play.” Any customer, regardless of
experience or expertise, should be able to install and configure a NAS
appliance quickly, often within minutes.

Normally, NAS systems can:

  • Be deployed anywhere in the enterprise.
  • Provide a pool of storage that all customers can share.
  • Offer unlimited customer access with no additional license fees.
  • Organize storage according to customer and/or workgroup needs.
  • Require little maintenance of their stripped-down operating systems.

File Sharing

Many small businesses boast a wide variety of systems – and operating
systems – including Windows, Apple Macintosh, UNIX, and Linux. A NAS
appliance can appear like a native file server to each of its different
clients. That means that files can be saved on a NAS system, as well as
retrieved from a NAS device, in their native file formats. It also means
that native security can be put in place to protect sensitive data. Most
NAS appliances, for example, can be integrated with Microsoft’s Active
Directory authentication.


Expanding a general purpose server is often not a cost-effective way to
increase storage capacity. Implementing a NAS system is. For a few
thousand dollars, today’s NAS appliances offer the same performance,
reliability, and feature sets for which enterprises have typically paid
$10,000 or more, and their management cost is significantly lower.

Personal NAS

Just as enterprise workers employ personal computers to satisfy their
remote computing needs, they will soon deploy personal NAS devices to
manage their escalating – and distributed – storage requirements. A
personal NAS consists of “a central hard drive on which you can store,
share and back up all files from multiple computers in the household. The
NAS drive connects via an Ethernet cable to a wireless home-network
router, which enables laptops and other devices equipped with Wi-Fi
networking to use the drive wirelessly.”

Since most enterprises, especially large enterprises, now support telework or
telecommuting operations, enabling employees to leverage their home
computing equipment for business purposes, enterprise officials will have
to revisit – and potentially rework – their telework protocols to accommodate
the use of personal NAS devices while still protecting and isolating corporate
data. This will become especially important in a post-COVID-19 world where work
will be handled on a more distributed and remote basis than ever before.

[return to top of this


1 “AFF A-Series." NetAPP. Retrieved June 2021.

2 “Network Attached Storage (NAS) Market Worth $48.0 Billion
by 2025 – Exclusive Report by MarketsandMarkets.” PRNewswire.
June 15, 2020.

[return to top of this