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The Way Business Is Moving

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Issue Date: October 2008

The NAS vs SAN debate rages on

October 2008
Armand Steffens, Netgear business development manager at Duxbury Networking

The low costs associated with disk-based data storage in the past motivated companies to simply add more disk space when capacity problems arose. Now, in the light of rapidly rising costs linked to this resource, Armand Steffens, a Netgear business development manager at Duxbury Networking, revives the long running debate as to which storage technology is best – network-attached storage (NAS) or the storage area network (SAN) – from a cost-efficiency point of view.

Vendors have been warning corporate users for some time now to revise their data storage strategies in the light of imminent price rises on disk-based storage resources.
Today, a more scientific approach is needed to the management of short- medium- and long-term data storage. In essence, companies need to actively manage data from the moment it is created until it is no longer needed, rather than passively warehousing it forever at ever-increasing cost.
They will also have to come to terms with the two technologies that are vying for pride of place in the corporate storage landscape: network-attached storage (NAS) and the storage area network (SAN).
At first glance NAS and SAN technologies may seem similar. A SAN is a dedicated network that is interconnected through a Fibre Channel protocol using Fibre Channel switches and Fibre Channel host bus adaptors.
Devices such as file servers connect directly to the SAN through the Fibre Channel protocol.
NAS, on the other hand, connects directly to the network using TCP/IP over Ethernet CAT 5 or equivalent cabling. In most cases, no changes to the existing network infrastructure need to be made in order to install a NAS solution. The NAS device is attached to the corporate network and assigned an IP address just like any other network device.
Best option
SAN protagonists have always underlined the highly redundant features of SANs through the implementation of multipathing and the ability to create fully redundant fibre meshes, obviating a single point of failure.
However, the initial investment in a SAN is expensive due to the high cost of Fibre Channel switches and host bus adaptors and the need for additional software – because SAN file sharing is operating-system-dependent and the facility does not exist in many operating systems.
When cost is a factor, NAS supporters point to the fact that NAS products are able to run over an existing TCP/IP network and, as such, are cheaper to implement than SANs.
What is more, NAS challenges the traditional file server approach by creating systems designed specifically for data storage. Instead of starting with a general-purpose computer and configuring or removing features from that base, NAS designs begin with the bare-bones components necessary to support file transfers and then add features.
Ease-of-use is an obvious feature of NAS. NAS products simply plug into the IP network and appear as ‘just another device’ using the file system and operating system used by client PCs. These include Windows, Unix, Linux, NetWare and Macintosh clients.
In addition, users can access files held in personal and shared directories on the NAS server and interrogate it in the same way they do on a normal Windows or Unix Server – with similar security and permissions.
And unlike general purpose file servers, client licence fees are not required, reducing cost of ownership as the network grows.
Cost effective
NAS servers are also the most cost effective way of adding storage capacity to the network, scaling from entry level 1U rack mount units, to fully redundant NAS Storage Servers incorporating RAID (redundant array of independent disks) technology.
With constant interest rate hikes, return on investment (ROI) is a big consideration today. NAS systems attempt to reduce the cost associated with traditional file servers. Rather than use general-purpose computer hardware and a full-featured network operating system – such as NetWare – NAS devices generally run an embedded operating system on simplified hardware.
Because of this feature, NAS storage servers install without the need to change the standard network configuration. And as they are designed specifically for network storage, a NAS tends to be easier to manage than a file server and can be up and running very quickly.
Reliability, ease of administration
NAS systems strive for reliable operation and easy administration. They often include built-in features such as disk space quotas, secure authentication, or the automatic sending of e-mail alerts should an error be detected.
Many NAS systems also support the Hypertext Transfer Protocol (HTTP) allowing users to download files in their Web browser from a NAS that supports HTTP. NAS systems also commonly employ HTTP as an access protocol for Web-based administrative user interfaces.
Opinion
Besides providing a reasonable alternative to traditional file servers in client/server networks, the new breed of NAS networking products has succeeded in cutting costs for most users. For example, entry-level NAS products containing 250-1000 gigabytes of storage can be purchased for less than R5000.
Besides cost, a NAS promises reliable operation and easy management. Expect NAS technology to keep evolving as the field matures even further over the next decade.


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