In an acronym-laden industry, it's no wonder there's confusion between the terms SAN (storage area network) and NAS (network attached storage). Sometimes, deciphering these acronyms feels more like a game of anagrams than a lesson in technology. Beyond that, though, both technologies are storage solutions. That creates additional confusion.
Despite these similarities, SAN and NAS are two distinct solutions. So, when looking for the right solution to your storage problem, don't pick haphazardly between technologies. Learn the distinctions between SAN and NAS, and choose the one that best fits your business needs.
Getting A Handle On NAS
The best way to define NAS technology might be to describe it as a "toaster," or network storage appliance. You simply plug it in and it works. This moniker speaks for one of the biggest advantages of NAS storage devices: the devices are extremely easy to install. "Even someone without an IT background can probably have a NAS device up and running within 15 minutes," says Kanti Purohit, CEO of TAC Systems (Huntsville, AL). "The devices are attached to a LAN (local area network) between the server and clients. The distinct advantage of this setup is that it provides storage to specific groups within the network." For example, if you had a marketing project group that was using scads of huge, scanned images, you wouldn't want to buy a server just to solve that specific storage problem. If you could find a cheaper solution to meet the group's needs, however, that might be a good alternative.
That is what NAS technology allows you to do. A NAS device could be hooked up to the network, so that only one specific group of users could access it. Everyone in the marketing project group could be connected to the NAS device, using it outside of the server to save scanned images. This scenario also touches upon several of the other advantages behind NAS devices.
Additionally, NAS devices can be a benefit because they take some of the burden off the server. Instead of bogging a server down with additional work, NAS devices handle storage needs separately. With NAS devices, requests for information are routed directly to the NAS device - not through the server.
What Is A SAN?
According to Scott Slack, vice president of marketing at Cranel (Columbus, OH), a fundamental definition of SAN would be, "‘An overall architecture that creates a separate network for a company's storage.' It uses traditional networking concepts, like hubs and switches, found in the LAN. A SAN is really a place to offload the storage from the LAN. It increases overall bandwidth, reduces distance constraints, and improves the overall connectibility and scalability of storage behind the servers." The complexity of the definition suggests that SAN is a more complicated solution than NAS. For this reason, there are probably more questions that a business should answer before diving into a SAN solution. Slack himself cautions that "SAN solutions are really a much more serious approach to architecting a company's data storage."
One of the first things that customers should be aware of when purchasing SAN storage is the distinction between SCSI- (small computer systems interface) and Fibre Channel-based solutions. SCSI devices, in all incarnations, have long been a standard for connecting devices to a network. While the envelope for SCSI technology is always being pushed, it is reaching its maximum capabilities. Fibre Channel technology, once prohibitively expensive, is dropping in price as it matures. The result is that SCSI devices will eventually be replaced by Fibre Channel-based solutions. Fibre Channel technology is, without doubt, superior. It offers far greater throughput than its SCSI predecessor. And, there are fewer distance restrictions when locating devices. But, because Fibre Channel technology is still emerging, it brings with it a degree of uncertainty. With so many vendors trying to establish themselves in this space, there arise issues regarding connectivity standards between available Fibre Channel devices.
Choosing From Proprietary And Open Solutions
As yet, no industry standards for Fibre Channel connectivity have been established, although they are currently being developed. If you purchase all of the components for a SAN from one vendor, then most of the connectivity problems will be eliminated. However, you may want to buy tape storage from one vendor and online storage devices from another. It's also likely that several other vendors will supply components for your SAN beyond storage
hardware. There's also software. And, this is where the lack of standards comes into play. If the hardware and software that make up your SAN cannot communicate, your business could experience a very costly mistake.
Slack suggests that businesses looking for a SAN solution conduct research to find a good vendor. There are two reasons for doing so. First, most businesses go back to their server vendor when looking for a storage solution. "That's a mistake," says Slack. "Most likely, the vendor will try to sell you another server - which is not often the right choice. You should find the solution that is best for your business, not for the vendor's."
The second reason to research a vendor relates to the state that most businesses are in when searching for a storage solution; they already have an existing IT infrastructure, storage, and networks. Adding a storage device can be complicated by the existing technology infrastructure. "That's why you should take a multi-vendor approach," says Slack. "Do not use a single vendor. A vendor that partners with other vendors will pull all the separate pieces of your existing system together and make them work. That's not the case with single vendor solutions."
Choosing The Right Storage Solution For Your Business
Businesses that want solutions to their storage problems have several options available. And, although NAS and SAN have been presented separately here, many experts agree the two technologies can complement one another. The specifics behind that integration will continue to evolve until both technologies mature.
In the meantime, companies should examine the needs of their businesses and compare those criteria with the solutions available at this time. The best match will be the solution that works best for the business — not the one that works best for the vendor.
Questions about this article? E-mail the author at DougC@corrypub.com.