NAS and SAN - a meeting of distinction

Journalists wanting a black-and-white distinction between what a NAS is and what a SAN is are partly to blame for the misunderstanding that two technologies will ultimately be decided by the click of a button in software, according to IDC's Asia Pacific storage research vice president Graeme Penn.

"It's a grey area with about 15 percent overlap in technology," Penn said, adding the two architectures will eventually converge. "Above the hardware there are two or three layers of software where the smarts are."

Penn said storage is not just about NAS and SAN and the distinction is so artificial that it is better to talk about the network storage architecture than the specific device.

"When data is stored on the network, end users don't need to know or care about the system in place," he said. "Which one you choose will depend on what you want to do. For an office, a NAS should be fine but if you have a requirement for database transactions a SAN is more appropriate."

Penn said the distinction is particularly blurred when the ability to partition one box into NAS and SAN functionality is exercised. And vendors like NetApp have had hybrid NAS-SAN solutions for about two years so users can't buy a pure NAS box as the hardware can handle both architectures together.

"The limitations are still with software development and APIs to enable end users to take advantage of a true network architecture; this will take time," he said. "Storage management software has come a long way from the NAS and SAN of five years ago. No one vendor has all the pieces, but this is improving because of licensing and package deals."

Penn said the software layer is becoming more integrated in response to user demands. For example, HP did have its system and storage management software separate but now the two are part of an integrated package.

IDC's Penn said the ABC and SBS are good cases of building storage networks with both disk and tape.

"Some of SBS and ABC's data needs to last for years and be accessed in a reasonable period of time," he said. "Object-based storage stores data in a different way again by storing multiple instances once."

Penn believes the drive towards software as being the key differentiator between vendors is the main reason why Sun Microsystems recently acquired StorageTek.

"Sun clearly didn't buy StorageTek for its tape libraries which it is already reselling; it bought it for the software technology and consulting expertise," Penn said, adding that Sun had little storage focus outside Solaris.

"The move also marks Sun's entrance into the ILM (information lifecycle management) space. The acquisition makes sense and gives StorageTek some benefits too."

Penn said customers are moving way from the purchasing trend of buying storage only from existing server vendors.

"Server virtualization is slowing server purchases [and] the ongoing server and storage consolidation has many facets - the data centre, servers, storage, and applications," he said.

Penn said RAID on individual storage within servers spread across many systems becomes a storage grid, which is indicative of the way the market is going - using software smarts to save purchasing more capacity.

"This is a threat to NAS and SAN," he said.

The demands of rich-media storage

With a five-year-old SAN information systems manager Greg Koen describes as "not suitable for streaming media", SBS is looking for a new solution that can cater for its complex corporate and media storage requirements.

SBS's existing enterprise storage environment consists of a pair of 880GB HP SANs and it is in discussions with HP, EMC and Sun to replace it. SBS will go to tender within three months and hopes to start building the new SAN within six months. The previous SAN was around the $1 million mark and Koen is confident of getting 10 times the storage for the same price.

"The current generation of SAN management software promises to be a lot better," Koen said, adding that SBS doesn't have NAS appliance but will consider it even though NetApp was "very expensive".

"For anything over Ethernet a NAS probably won't cut it," he said. "For really high data volumes a SAN is the way to go."

Over the past two years SBS has replaced a legacy card retrieval system for its news and current affairs tape archives, and has looked at digitizing all the subtitle footage to turn it into meta data.

"We try to make an informed guess [about storage] so we can move data to other positions," Koen said. "Oracle and Microsoft have tried to show us a few things but the real gotcha is the meta data."

SBS is now working on getting its second generation digital television systems running this month in time for the Ashes cricket series. This system is pure digital television.

At fellow government-owned broadcaster ABC, both a NAS and SAN environment is managed after it went to market for a commercial offering. Hitachi Data Systems (HDS) won the SAN system, and NetApp won the NAS space. The NAS houses the data for the Web sites, intranet, radio archives, and a number of file-based applications like file serving, while the SAN infrastructure is used for anything database driven or host-reliant, such as the CMS for publishing content to the Web sites.

Fred Spark, the ABC's systems management services manager, said to create an architecture without both [NAS and SAN] "doesn't make sense".

"In the long term, NAS and SAN architectures will merge and the software will be the differentiator," he said. "Tick a box if you want a NAS or a SAN."

Spark said a SAN is applicable for anything that is host-based or closely integrated with the host.

"A SAN with block-level read is ideal for data-intensive applications," he said. "There is movement in the commercial SAN market. A lot of the 'magic' around the SAN is being replaced by easy-to-manage commercial components and this is beginning to happen now."

Spark said the NAS market is becoming very much commoditized and shopfronts and branch offices will benefit most.

"IBM is now re-branding the NetApp kit and it is certainly easier to move from one to another," he said.

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