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RSS feedsMost network managers feel, rightly, that when they buy a piece of hardware, it should not only work well but also work with existing equipment.
Add to that the need to work with anything that may be purchased in the future and you have a veritable nightmare of interoperability. In the storage industry, moves are afoot to make all this less painful. Although the very mention of storage is coma-inducing to some, it is important to get it right as the benefits can be enormous.
There is still confusion as to which storage technology is most appropriate to each individual enterprise. While some will find network attached storage (Nas) most appropriate, Fibre Channel - and the storage area networks (Sans) that use this technology - could be best for very high bandwidth storage applications such as video streaming, webcasting and the back offices of large multi-nationals.
"That is where we are really seeing Fibre Channel being used," explained Ajay Lukha, director of StorCase Europe. "If you look at the mid-cap companies, that's primarily where the problem is. I think they don't quite get it yet. There's a lack of proof out there that storage networking is beneficial."
And Paul Sleep, director of European Marketing at Nas device manufacturer Auspex Systems, doesn't think that that confusion will go away. He believes that network managers are getting more confused because some experts are promoting iSCSI and Gigabit Ethernet over Fibre Channel.
But he believes this confusion will encourage them to stick with Fibre Channel. "I think it will assist those who have adopted Fibre Channel by ensuring that their integration of different vendor switches and products is as easy as possible - without unexpected interoperability problems," said Sleep.
Lukha feels that, although the technology is in place, hearts and minds have yet to be won over. He believes there is an 'educational cycle'. "I'm sure, with local area network [Lans] and Ethernet, some people didn't buy in until a lot of others had, or had understood the benefits. There are parallels in storage networking," he said.
There are times when only one - Nas or San - will do the job. But most network managers will have to cope with hybrid systems as the two converge. People may have a San infrastructure in place and run Nas devices on it. Alternatively, they may see Nas as a stepping stone, expanding their Nas devices into a fully-fledged San.
A new approach
What we are starting to see is a change in companies' approach to storage. Rather than buying the servers and then thinking about storage, they are beginning to add intelligence to the Nas 'head'. This enables it to act as an interface between network clients and storage.
The Nas head can connect to remote storage disks, much like a San, as well as to tape libraries. Clients generally access a Nas over an Ethernet connection. The Nas appears on the network as a single 'node' that is the IP address of the head device.
In cost and manageability, a Nas device wins out over a general purpose server because it targets data storage rather than providing catch-all functions, as the general purpose server would be doing.
Sleep expects Nas and San to converge in five years, along with Gigabit Ethernet and iSCSI. "All I can safely predict is that networked storage will overtake direct attached storage. Will San or Nas win out? I don't think either will. They will converge into a new breed. We are seeing this already," he explained.
Apart from convergence issues, Fibre Channel looks set to be the prevalent standard for the next two years. Although iSCSI is based around standard protocols - changed to cope with storage - it is still going through an adoption cycle. It could be eighteen months before it becomes mainstream. The cost of implementation is reputedly a lot less and it has the potential to co-exist with Nas and San.
Lukha is intrigued by iSCSI. "The reduced capital outlay, relative to Sans, could make it a good option for small companies," he said, but even a small company might find that Sans suits them as there are so many variables out there. "The debate will go on. iSCSI is a really interesting technology; it's yet to be proven to be faster but it certainly promises to be cheaper at this point."
iSCSI is one of two main approaches to storage data transmission over IP networks; the other, Fibre Channel over IP (FC/IP), translates Fibre Channel control codes and data into IP packets for transmission between geographically distant Fibre Channel Sans.
Growing pains
Fibre Channel proponents are sceptical about iSCSI. Paul Trowbridge, director of marketing at Brocade, thinks that, while there is a lot of talk about iSCSI, there are, as yet, no products deployed. He believes that most business at the larger end of the market, such as data centres, have storage problems right now in terms of continuing growth.
"If you were deploying a data centre, particularly with large Oracle database-type applications, you'd do it through Fibre Channel," he said, adding that, as a standard, FC-SW-2 (Fibre Channel SWitched fabric) is mature and clarifies all interoperability issues. It is an extension of the FC-SW-1 standard currently in use, but places greater emphasis on management of the switches.
The new switching standard is supposed to be a move towards guaranteeing interoperability, but Sleep adds a cautionary note. "Think back a few years to when RS-232 was a standard. There were five different ways it could be implemented. We are seeing the same problem again: people see the word 'standard' and expect it to mean 'no problem'," he warned.
Sleep still sees protocol and interoperability issues but says the Fibre Channel Industry Association and Storage Networking Industry Association have done a lot towards establishing the boundaries for Fibre Channel, making people more comfortable adopting it.
Switch interoperability is a mainly theoretical discussion for customers, as most tend to install one vendor's equipment. If they buy Cisco, Foundry, Extreme or Nortel, they don't tend to install mixed switch environments.
However, they like to have the safety net of standards-based equipment as, if they did need or want to change, they could do so without impacting anything else in their business. FC-SW-2 offers the last bits of interoperability requirements by designating how switches pass information to one another over and above Fibre Channel frames. Yes, they've always been able to do that, but previously there was no way of exchanging routing and zoning information between switch vendors.
A big chunk of FC-SW-2 uses code from Brocade called Fabric Shortest Path First (FSPF) which is the routing algorithm used in a San. It's just like OSPF or RIP protocols used in data networks for exchanging routing information.
Interoperating Sans
"We have shared our code with the other vendors. That was one of the last hurdles to overcome," said Trowbridge. "What FSPF means to the customer is not so much that they will have mixed switches on a single network, but that they can buy another company or data centre which might be running other vendors' switches. It means you can interoperate those Sans. It resolves the last remaining question marks between switches."
The 'next big thing' with Fibre Channel is 2Gb San, which was defined as a standard last year. Most companies involved in developing Sans are migrating to 2Gb Fibre Channel for San switches.
Most of the vendors will be shipping 2Gb San switches in the second half of this year, offering higher bandwidth capabilities. Not many current storage arrays support 2Gb, but more are in the pipeline.
Gigabit Ethernet and Fibre Channel use the same physical layer. The Gigabit Ethernet standard took the Fibre Channel standard that was already written and reused it. The same thing is going to happen with 10Gigabit Ethernet - the next development.
The physical interfaces on the switches are identical. What you are using are different protocols. So where Ethernet defines how you put frames onto the fibre or copper and how you manage the flow of traffic, Fibre Channel does the same thing slightly differently.
Getting the message across that Sans are here - and viable - is key. Initiatives such as SanMark, which is about achieving interoperability between different vendors' hardware including switches, hubs and routers, could work in Fibre Channel's favour.
The perception is that a turnkey solution is very expensive, and SanMark could enable people to shop around for components with an added 'security blanket'.
Lukha believes that education is important, and that the Fibre Channel industry needs to overcome objections on price and implementation.
"These are sales objections. The industry is slowly addressing them, but the message has to be consistent," he said. One objection to Fibre Channel is the skills shortage. "We don't have any experts in our IS department, let's not go there!"
A 'disaster-tolerant' environment
Halifax, one of the largest mortgage lenders in the UK and one of Europe's largest financial services companies, implemented a San infrastructure in order to create a disaster-tolerant environment for critical financial data.
The main Halifax data centre San is based on Brocade SilkWorm fabric switches, which provide a "reliable and scalable" networking foundation for its storage environment.
Halifax has deployed more than 50 SilkWorm fabric switches in one multi-fabric San, spanning servers and storage from multiple vendors. Halifax has also deployed several other Sans across the company, with nearly 100 fabric switches implemented to date. The company's networked storage solution was deployed in conjunction with Hitachi Data Systems.
"We chose Brocade because of their dominant market position, their technology leadership, and customer acceptance of Brocade as the preferred platform for networking storage," said Bob Sibley of the company's Technology Services division. "Deploying the San has enabled us to achieve business continuity through the implementation of dual dark fibre links between our primary data centres and Brocade Extended Fabric technology.
"This configuration creates a single fabric infrastructure for transparent data replication between systems and sites. The deployment of the San has also helped us to implement Lan-free backup. Altogether, the project has given our organisation measurably better backup performance."
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