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Fibre channel's SWAN song

Fibre channel's SWAN song

For many people, storage is something that runs in the background, something you don't really think about - until the unthinkable happens and disaster recovery becomes the priority.

In recent months, disaster recovery has become a major issue, if it wasn't already, for companies around the world. The ability to quickly bring sites back into production with minimal trouble is the goal, whether a company is dealing with terrorist attacks or power outages.

Traditionally, the way to handle recovery was to make tape backups and ship them to another site. But what if you could keep a complete copy of your precious data on the other side of the world and access it at a moment's notice? This is the promise of SWANs (storage wide area networks), the augmentation of SANs.

Pooling resources

SANs were originally conceived as a way for companies to manage their storage resources and an ever-increasing mountain of data in a consolidated fashion.

Traditionally, companies relied on direct-attached storage with servers connected straight onto the system and independent of each other. The downside of this approach is that islands of data can get lost within large corporations. Plus, some servers could be under utilised, with others stretched to capacity. SANs promised to alleviate these problems by connecting storage devices together over fibre-channel networks.

A major limitation of fibre-channel SANs, however, is distance. SANs are great for single-building installations where their 10-kilometre limit is irrelevant, but for companies with national or international operations, fibre-channel SANs don't provide the complete solution. This is where SWANs come in.

"SANs with a 10-kilometre radius are a no-brainer," says Simon Elisha, senior software engineer for Veritas in Australia and New Zealand. "When you get to 30 or 40 kilometres it starts to become more difficult." Consolidating dispersed SANs, says Elisha, would enable companies to more quickly realise the investment they've made in storage networking.

There are other reasons SWANs are gaining an increasing amount of attention. Abie Gelbart, product marketing manager at EMC, says disaster recovery is one of the driving forces behind SWANs. "SAN consolidation - enabling companies to join SANs to create SWAN - means we will start to create an environment where it doesn't matter where data lives," Gelbart says.

Some companies also have a pressing problem with space. If you have an inner-city office, there's only so far you can stretch your server room, points out Greig Guy, solutions sales director for Hitachi Data Systems. Regional offices can, in this instance, offer room for companies to grow their storage capabilities within their current physical premises.

Businesses are also more demanding of their data. For example, a company may have a CRM operation in a regional office but head office wants to run a report from the system. "You're not going to want to run it against a live system," Gelbart explains. "Instead, using a SWAN you could make a second copy." Copies of production data can also be used by a company's development teams to test new applications, he adds.

If the point of SANs was to save on storage administration costs and make the most of a company's resources, imagine the savings that could be made if this concept was taken to all sites? In some ways the goal is to build a storage network as wide-reaching and easily managed as data networks are today.

Boom time

The concept of SWANs has prompted a mini-boom in the storage marketplace - just like the networking industry several years ago. Despite all the doom and gloom of dotcom crashes and falling PC markets, storage vendors are hurriedly building and releasing storage networking products based on an avalanche of new standards like iSCSI (Internet SCSI) and iFCP (Internet fibre-channel protocol), which, it is hoped, will enhance the scope of SANs and overcome limitations like distance.

For vendors, there's a great deal at stake. Research company Gartner predicted mid-year that the networked storage market will exceed $US10 billion in annual sales by 2004, with storage investments taking up to two-thirds of the typical company's IT budget. Networking over IP could also help vendors take the SAN message to smaller companies that have avoided the cost of implementing a fibre-channel network. "Everywhere we go, iSCSI is a hot topic," says Mike Sparkes, Quantum ATL's Asia-Pacific product marketing manager. "I think it will be really useful for the low end; for those who wanted to build a SAN but found it too expensive."

At the same time, the market has seen some convergence with the networking world, with vendors like Cisco building switches for storage networks based on IP networking. The incumbent players are also starting to feel pressure from new storage startups. Gartner analysts told attendees at the company's US Storage 2001 conference in June that around 200 startups are looking at iSCSI. One fledging firm garnering a lot of attention is Nishan Systems, which has already launched a series of IP storage switches.

"The startups are creating some heat," Veritas's Elisha admits. "This is often a good thing for the industry - so long as people don't rush in before the standards are ratified."

Ready for prime time?

To create a SWAN today you will most likely need to look at dense wave division multiplexing (DWDM) for the level of speed and reliability most storage applications require, since buying dark fibre connectivity from telcos can be an expensive proposition.

Alongside the cost issue is the management concern. Most businesses already have an IP network in place for data networking and staff with knowledge of the protocol to manage it. Still, being able to consolidate data and storage networks holds a lot of promise for IT managers looking to ease management issues and get more out of existing infrastructure.

The formation of the IP Storage Forum in February by the Storage Networking Industry Association (SNIA) really got the ball rolling on storage networking over IP. The forum is curtion company. At the time, HP said it would begin shipping the iSCSI, products in the first quarter of 2002 (the standard probably won't be ratified until the early part of next year). A month earlier, IBM launched its IP Storage 200i appliance based on iSCSI for linking data storage systems over IP. Cisco got an early start on the market with its iSCSI SN 5420 Storage Router, which allows IP-connected hosts and servers to access a fibre-channel SAN. At the device end, Quantum has an iSCSI tape library that can operate over IP networks.

Wait and see

Standards aren't the only issue to be resolved before IP storage networks become a reality. EMC's Gelbart suggests that many companies' existing IP networks won't be able to cope with all the data currently handled by their SAN. Similarly, there are performance issues with IP, mostly to do with latency and quality of service. The "best effort" nature of TCP/IP and Ethernet may not be the optimal approach for storage. Plus, applications that can't tolerate much latency will also face problems over IP storage networks.

"Questions remain," says Gelbart, who believes that mass shipments of iSCSI products are 18 months away and that the technology will need time to prove itself. Gelbart also points to new technology that will lift the speed of fibre-channel networks to 2GB, with 10GB not too much further away. Figures from IDC also predict that the fibre-channel market isn't going away anytime soon, and in fact will grow from nearly $US1 billion last year to $4.83 billion by 2003.

Nevertheless, "everyone's keeping a close eye on the new standards and feverishly developing products", Gelbart says.

Paul Cosgrove, IBM's business development manager for storage networking, has no doubts that iSCSI will have a major impact on storage networking. He argues that many of the issues to do with latency will be resolved through bandwidth increases and improvements to switching technology. What's more, vendors are starting to work with partners to ease iSCSI storage networking into accounts that may not have considered SANs, especially smaller companies. "The channel is absolutely crucial," says Cosgrove. The launch of new protocols enables choice in the market but also means companies will need to weigh up more technology considerations, which is why SIs will find themselves in demand.

Only time will tell if all standards will be successful in the market. In the meantime there are high-performance, secure storage networks to create. One thing's for sure: 2002 is set to be a hot year for storage networking.


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