STORAGE: The Network-Attached Server

As
the network administrator for a workgroup LAN, consider this scenario:
once again, one of your network file servers is running out of storage space.
You send out the usual broadcast messages for users to delete old files, but you
know you haven’t eliminated the problem, only postponed solving it. It’s
time to rethink your options for increasing disk storage space.

If your network server has an available drive bay, you might consider adding
a hard disk. This sounds economical. But you’ll need to take the server off
line, and you’ll hear from your users about that. After totaling up the time
and effort it takes to reconfigure the server–and probably sacrificing part of
your weekend–it may not add up to much of a bargain.

You could add more network storage with another PC server. That would put a
bigger dent in your budget, especially after purchasing the usual operating
system software licenses. Plus, it will take a day or more of your time to
configure the new server and integrate it into your existing network.

Or you could consider a third alternative: a new network file-sharing
technology called network-attached storage (NAS). NAS file servers expand
storage capacity independent of the PC server and provide a simple,
cost-effective solution to adding network storage.

Traditional storage: Shortcomings

Traditionally, organizations have addressed the need for more storage by
adding disk drives to an existing server or installing a new general-purpose
server on the network. Both solutions can be time consuming for the IT
professional and disruptive to the workgroup, since the server must be taken off
line. To minimize such disruptions, hardware upgrades are usually scheduled for
off-hours, requiring the IT staff to work evenings or weekends. However, in
environments with demands for high data availability, there are few or no
convenient time periods for users to be without access to their network
resources. In addition to the user inconvenience, any time spent adding storage
is time that the IT professional is not available to deal with other network
problems.

After hardware, software licenses and installation time are considered, a new
server for the workgroup can cost anywhere between $3,000 to $10,000. It may
take a day or more to install. Even after the new server is installed and
tested, problems may occur once the system is on the network and put under load.
A new disk drive may be relatively inexpensive, but installation can take
several hours to half a day. As demands for data storage continue to grow,
traditional methods of adding storage to the workgroup have become costlier.

Next generation storage

The PC has paved the way for network server technology. Over the last two
decades, PCs have evolved into general-purpose network servers responsible for
managing a number of complex functions including storage, application delivery,
printing and gateway functions. All activity is routed through this
general-purpose server, taxing server resources and, often, creating a
bottleneck. Throughput and response time suffer as a result.

In an attempt to alleviate these conditions, system administrators have begun
to modify general-purpose network servers to deliver a limited set of
specialized functions. One such specialized need is file sharing. Many PC
servers are configured with a large amount of storage and dedicated as online
file repositories. Because of the general-purpose nature of PC server design,
its deployment as a network file server carries unnecessary and unused
components, not to mention the IT resources needed to fine-tune a multi-purpose
network operating system for a specific function.

NAS file servers were developed as an alternative to the general-purpose
server. They are single-purpose appliances, dedicated as file servers, which
provide a flexible and inexpensive alternative for adding storage to the
workgroup. NAS servers connect directly to the network, not to the file server,
giving rise to the term “network attached”. Workgroup users cannot
distinguish between accessing files on a general-purpose server and on a NAS
file server. The only difference a user might notice is improved network
performance and the ability to access files even if the general-purpose server
is taken off line.

Unlike traditional servers, whose operating systems charge a “per
seat” licensing fee for each user connected to the server, there are no
licensing fees with NAS servers. The system software is embedded, and software
upgrades are usually free via Web download. With a NAS server, you pay for only
those hardware and software components that are needed for network storage.

Choosing a NAS file server

To meet the workgroup’s increasing demand for data storage, NAS file
servers are rapidly growing as a product category. They are easy to install and
maintain, and they are more economical to own and operate than traditional,
general-purpose file servers. Because these products are relatively new, it may
not always be clear how to evaluate them compared to traditional storage
options. What product features are important when choosing a NAS server? What
benefits should you expect? The following criteria will help you evaluate and
select the best product for your workgroup LAN.

Easy installation: Adding a NAS file server to an existing network should be
as simple as “plug it in and turn it on”. The default installation
should take no more than 15 minutes. The NAS server should be easy to install
and integrated into an existing network without disrupting other servers, and
there should be no additional server or client software to install. Network
users will have access to all their files and network resources during the
installation process.

Look for a solution that is operational in no more than three steps:

  • Plug in the power cord

  • Connect the
    Ethernet cable

  • Turn on the
    power.

Compatibility with existing networks: To ensure easy
integration into an existing network, choose a NAS server that is compatible
with your established networking protocols and workstation types. Check to see
if the server can respond to a dynamic host configuration protocol (DHCP),
bootstrap protocol (BOOTP) or reverse address resolution protocol (RARP) server
to receive an automatic Internet protocol (IP) assignment. If you opt for manual
IP address assignment, look for an easy-to-use installation wizard that will
help you step through the task quickly. The better a NAS server supports your
existing workgroup environment, the less time and effort it will take you to
configure and integrate the new NAS server at installation.

Intuitive Web administration: Since a NAS server is
specialized for a single function, it requires limited maintenance. Any routine
administration or customization of the NAS server is easily performed via a
simple Web browser from any client on the network or from anywhere on the
Internet. While evaluating a NAS server, check for an intuitive, easy-to-use
graphical user interface to the Web browser.

Cross platform file sharing: Cross platform file
sharing can be a headache for the IT manager in workgroup environments where
there is a mix of Windows, Apple Macintosh and Unix or Linux workstations
requiring support for Microsoft, Novell, Apple and Unix networks. To address
this problem, some NAS file servers have been pre-configured to support more
than one network protocol for cross-platform file sharing. A NAS server should
appear on the network like a native file server to its clients with files saved
and retrieved in their native file formats. To protect your investment in
existing hardware and software, choose a NAS server that is pre-configured to
provide concurrent support for those network protocols and workstation types
already in use in your organization. Conformance to industry standards and
compatibility with existing equipment will ensure an easy installation and the
long-term use of the NAS server.

Network security: If security is a concern on your
network, choose a NAS server that integrates into your existing network security
by supporting NT Domain or NetWare Bindery for passthrough security. Integration
with NT domain security for passthrough user authentication provides a superior
solution over password security for network shares.

Compatibility with backup policy: After storage and
file serving, backup is the next most common use for a NAS server. There are two
types of backup usage that should be considered during your evaluation: using
the NAS server as a backup device on the network for workstations files; and
using the NAS server as part of an archival solution for enterprise backup.
Check to see if the NAS vendor offers a solution to back up workstation files
onto the file server. In addition, the NAS server should be compatible with
leading network backup application software used, or anticipated, in your
organization.

Improved performance under load: A NAS file server,
when all resources are optimized for the single task of file hosting, can offer
superior performance over a general-purpose server. Because a file server is
primarily I/O bound, criteria traditionally used in measuring PC server
performance may not always apply. For example, processor speed and memory do not
create as great an impact on a file server as they do on an application server.
When a file server is under load, data throughput is the most important
measurement. Investigate how many concurrent users the NAS server has been
routinely tested to support. A file server should be able to comfortably support
thirty or more concurrent users in a workgroup of average size without
experiencing a severe degradation of response or drop in network connections.
When performance is an important consideration, choose a product that supports
advanced disk configuration such as disk striping (RAID 0), where two or more
disks are combined into one large volume and the data striped across the disks.

High reliability: Single-purpose NAS servers are more
reliable than general-purpose servers that are designed to handle diverse tasks
are. With NAS servers, all unnecessary components have been removed, resulting
in a streamlined, highly integrated product. A higher degree or integration
enhances the NAS server’s ability, and fewer components reduce the risk of
failure. The embedded operating system has been optimized for file system I/O
and networking.

When reliability is important, look for NAS file servers that
support data redundancy features like disk mirroring (RAID 1) where the content
of one disk is duplicated onto a second disk. Data striping with parity (RAID 5)
is an important feature to look for in NAS servers configured with three or more
disks.

With NAS servers, users have access to their data even if the
general-purpose network server is unavailable. This in turn makes the network
more reliable, reduces the load on the general-purpose server, and minimizes the
exposure of a server outage.

Portable storage: Using the NAS server as a portable
or temporary storage device enables a number of new applications. For example,
the NAS server can be installed temporarily on the network as a scratch server
while the general-purpose server is taken off line for maintenance. Or the NAS
server can be used to store large graphical presentations and easily transported
and installed at trade shows, customer sites or remote offices. If the NAS
server is being considered for applications like these, look for a lightweight
device with a compact footprint.

Courtesy: Quantum Corp

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