NAS and SANS: which best suits your needs?

Is the network attached storage approach a mirror-image of storage area networks or are there distinct advantages to implementing...

Is the network attached storage approach a mirror-image of storage area networks or are there distinct advantages to implementing one over another? Simon Quicke reports

The mountain of data being generated by firms is causing a storage crisis which, if left ignored, could cripple the corporate network and cause businesses to lose competitive advantage. It is not too late to start tackling the problem and many of the solutions involve talking about storage area network (San) or networked attached storage (Nas). Despite rumours to the contrary the two approaches to solving network storage can be run together - it need not be an either/or decision.

San is a storage architecture based predominantly on a fibre-channel network, which can store and manage data on one independent system. Nas can be attached to the existing network and run off the Ethernet through TCP/IP connections. Both offer the ability to be more flexible with storage and increase capacity.

Deciding which option to choose depends very much on what your storage needs are and the kind of data being moved across the network. San is ideal for handling large blocks of data whereas Nas is more able to handlebyte-sized files.

"It is horses for courses," says Chris Atkins, storage marketing manager at Sun Microsystems. "Nas is the way of the world at the moment and will be for the next 12 months."

The impression that San is the inevitable goal that will provide all the answers permeates the storage world. But to claim that Nas is simply a stepping-stone towards a San environment is complete rubbish, says Frederick Fabricius, regional San manager at IBM. He says that many organisations will find all their needs satisfied by Nas, and that the San option is not universally applicable.

In terms of hype, San beats Nas hands down and it is hard to think about networked storage without getting the sales pitch that San is the only real option.

"Some suppliers claim that a San can solve everythingexcept worldhunger, but you have to take a step back and take the hype out of the equation," says Donal Madden, UK storage business manager at Compaq.

Cutting through the sales pitch is the first challenge on the route to finding out more information about San. "People don't understand what it is trying to do,"adds Nigel Houghton, technical account managerat Gadzoox.

But despite the need to be cautious and consider the merits of Nas fairly, most market research suggests that San is the unstoppable direction the market is heading in. Frost & Sullivan predicts that the European market for San will grow from $1.9bn in 1999 to $64.1bn by 2006. It is no surprise that most companies are being advised this is where they should be investing for the future.

Those pushing Nas emphasise the ability to attach the equipment to the existing network. "Nas attaches directly to the Ethernet, and contains its own thin server and provides a pool of storage where and when it is needed. This is without the cost of putting in a server to host and manage it," says Paul Sleep, library products manager at M4 Data.

San offers these claimed benefits:

  • Improves flexibility

  • Eases storage management

  • Improves performance

  • Allows linked storage over wide geographical distances

  • Increases bandwidth allowing back-time to be reduced

  • Reduces costs

    The most attractive benefit of a San is the ability to unify storage and reduce the duplication of tasks, ending the time-intensive process of backing-up to different servers and the effort involved in balancing storage across a network capacity. The time spent by IT administrators looking after a San is less than it would be if stored data were left stored on discs and servers on an ad-hoc basis throughout a network.

    "The reasons why most people are moving to San today is because of a desire to reduce costs and because maybe they can consolidate their data," says Steve Lewis, San product manager at Dell.

    But getting from the discussion stage to the finished San is a path fraught with dangers. The amount of misinformation about both Nas and San systems causes major confusion whenever they are considered.

    There is a tendency for some storage suppliers to oversell the benefits of their technology. There have already been quite a few cases of businesses buying San solutions only to be left scratching their heads when it does not perform all the miracles promised in the sales presentation.

    The market is still immature and the lack of technical ability in the market is exacerbating the confusion.

    "The problem with San is that it does not always address the problems it has been purchased to solve because of immaturity and lack of knowledge," says Tom Lahive, director of European marketing at Storage Networks.

    "Everyone has oversold the capability of San and some companies are buying it, expecting it to solve some specific problems, but they are finding that once it is deployed they are not receiving those benefits," says Lahive.

    The current immaturity is being tackled and most San specialists expect significant improvements in the market and increased knowledge about the products to reduce confusion over the next year.

    Because Sans are still relatively new there are problems with interoperability between devices, despite the establishment of standards. Some suppliers advise that a purchase should be made with one partner only, and warn against a pick-and-mix approach.

    Sleep of M4 Data says, "The large companies sell their own families of San modules, which they have tested and can guarantee function together. A lot of resources are being applied within the industry to build interoperability labs, which will certify products as San-compliant, but these are not up-and-running as yet."

    The next stage in San development is "open San", where all products will work with each other. This is only about 18 months away, and in the meantime caution and a good relationship with a single partner should steer most organisations through the interoperability minefield.

    "The ultimate goal is a complete and open standardised San but we are not there at the moment. Some are nearer than others and the market is moving towards standardisation," says Tim Wilkinson, technical services manager at Storm.

    While there might still be some issues with the hardware, software engineers are working to improve the management side of San. In the next 18 months this is expected to be a growth area by those working in this part of the industry.

    Several suppliers - such as Tivoli, Veritas and Computer Associates - are capable of helping with the management software side of the purchase.

    Cautiously and slowly

    The best advice seems to be to take any decision, particularly a San migration, cautiously and slowly. Changes to the network storage architecture should not be taken lightly, and most suppliers advise that in the case of San things should be taken in stages.

    The first stage of a successful migration to San is to start a pilot, which should be run for three to four months, in an isolated part of the business. Once the pilot is completed San migration can be undertaken more smoothly, depending on the size of the network.

    "In three to four months you will be able to appreciate what you will get out of it [in performance benefits] and you can always put in a small San and then grow it," says Mark Hiley, UK sales and marketing manager at LSI Logic Storage Systems.

    Sans can be expensive, but Houghton says it is worth it. "When it is all networked the data can be managed more efficiently and when you can see all the storage activity from one console it more than makes up for the hardware expenditure."

    The sheer amount of data being generated by the Internet, e-mail, presentations and financial information is causing firms to think seriously about what they are doing with their stored data, but more importantly, how they can manage that information.

    Doug Rainbolt, director of sales and marketing for Exabyte Europe, warns that ignoring the storage issue is going to blunt a company's competitive edge. "The amount of data is exploding and imagine what is going to happen in three years. Firms who have started to manage this will have the competitive advantage," he says

    There are real benefits to be gained from implementing a San now, but it should get easier over the next 18 months. Nas also offers a remedy to storage woes. Making the effort now to find out about network storage is going to be worth it because the movement towards San and Nas seems to be unstoppable, and the arguments in favour of network storage are likely to prove to be too attractive for most organisations struggling with their data.

    Three-step path to San uptake

    1. Decide what your storage needs are and whether a San is going to be an answer to those problems. Try to ignore the hype and get suppliers to be realistic in their proposals. Be wary of overselling and rash promises from suppliers. Bear in mind that Nas might be quite adequate in the short term, with San as a longer-term solution.

    2. Run a pilot for three or four months in a subdivision of the business to measure the benefits of implementing a San. This should give time to notice the promised improvements in performance and ease of storage management.

    3. Start the migration across to a San but take it carefully and ensure that a trustworthy partner has been chosen to make the migration match the aims originally set.

    Making real savings

    Retailer Littlewoods has been consolidating its hardware and software to a unified system. To help it through the project it teamed up with Veritas Software in a £1.13m deal to improve its storage management. That money is going into back-up software and establishing a centralised online management system.

    David Hallett, group IT director at Littlewoods, says he hopes to shave hours off time spent administrating back-up and storage tasks. "Our storage capacity has now reached over 20 terabytes, and it is growing rapidly.

    "I would estimate that in terms of performance gain, saving back-up time, pooling of DASD and reduced maintenance, Littlewoods is saving over £750,000 per year using this consolidated storage strategy," Hallett says.

    "This rate of return on investment is easily meeting our goals, and the benefits are real - reduced maintenance costs and fewer operators. From the customer perspective it improves the up-time of applications and moves the company far closer towards the goal of 24/7 operation."

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