Blade servers: On the cutting edge

Blade servers offer a space-saving, lower-cost alternative to rack-mounted systems. So where's the catch? There isn't one.

Blade servers offer a space-saving, lower-cost alternative to rack-mounted systems. So where's the catch? There isn't one.

Anyone who has visited the average data centre knows what a tangled, complicated environment it can be.

With hundreds of rack-mounted servers in rows, each of them trailing their own power supply and network connection cords, the amount of cable spaghetti can be daunting. Systems administrators sometimes resemble ferrets, scurrying down tunnels of tin, pulling and plugging cables in a bid to keep the whole intricate set-up running smoothly.

Rack-mounted servers make the business of server management more difficult, as well as other downsides such as creating excess heat and a shortage of floorspace. Perhaps this is why blade servers are currently enjoying their position at the cutting edge of server technology (if you'll excuse the pun).

A step ahead
Blade servers take server consolidation further than it's ever gone before. The concept focuses on increasing server density by using a trick from the networking switching industry: a high-capacity, low-footprint chassis is used to house servers on a card, each of which is known as a blade.

Blade servers promise customers the ability to shrink their server farms while retaining the same amount of processor power, or even increasing it. In short, with data centre space being prime real estate, it's all about increasing your performance per square foot.

The other upside is that whereas it can be difficult to manage rack-mounted servers, blade server vendors are shipping their own management software to help administer all the blades from a single point.

Major server vendors are busy capitalising on the blade server market. Companies such as Sun, IBM, Hewlett-Packard and Fujitsu have either released or announced plans to release blade server offerings, mostly based around a passive backplane.

An active backplane, such as a normal PC motherboard, contains most of the electronic circuitry (such as the processor and memory, for example) to support the cards that are plugged into it.

A passive backplane, used by companies such as Dell and IBM, contains little or no circuitry. Instead, the supporting circuitry is either contained on a separate plug-in blade (making it easier to swap out), or on a separate piece of circuitry that sits behind the passive backplane, handling the supporting functions.

Passive backplanes are appropriate in a blade server architecture, because each blade is generally a dedicated server, which means it contains its own memory and processor power.

Consequently, they won't need to share a single memory resource like some symmetric multiprocessing machines might do, and they won't need to communicate with each other (for which an active backplane would be needed).

Timothy Dougherty, director of blade server strategy at IBM, explains that when Big Blue's machines launch later this year they will use a passive backplane attached to an Ethernet switch. "Because it's not an active backplane, I can do things like upgrade components on the way," he says.

There are different standard backplane specifications in the market. A common one is the compactPCI (CPCI) specification from the PCI Industrial Computer Manufacturers Group (PICMG). The organisation also released another specification called the CPCI/packet switching backplane specification.

This layers a packet-switched Ethernet system over the CPCI specification, creating what the PICMG calls an embedded system area network (ESAN). The advantage of the newer standard is that it is more resilient because two separate Ethernet networks are used, explains the PICMG.

This also improves performance. Other standard backplane technologies, such as the 3GIO bus, will make an appearance on the market in the next 12 to 18 months, but the one that is causing the most interest is infiniband.

A networking technology with a 48Gbps throughput, infiniband is still in the early stages of development. It will be of use in markets such as storage area networking (SAN), but it holds much promise as a backplane standard too, according to industry commentators such as Hendrik Wacker, European board director for the Fibre Channel Industry Association (FCIA).

Wacker is interested in blade servers because he thinks they will help to fuel the growth of the SAN market. Most blade server devices have little or no storage capacity beyond the basic hard drive storage needed to hold an operating system. They get their storage capacity either from a directly attached RAID storage system, or more likely from a network-attached storage (NAS) or SAN system.

The backplane technology effectively creates an embedded network of servers and "we believe this will happen either in a proprietary way or a standardised way, which is what infiniband plans to do in the future", Wacker says.

The advantage of using a standard backplane is that it provides a choice of server blades, explains Chris Franklin, HP marketing manager for servers, Itanium and Linux. HP is manufacturing its blades to the CPCI standard and has been gathering together a community of other blade vendors which also support the standard. Adherence to standards will create blades serving functions other than servers, such as switching and routing for example.

But Franklin, too, believes infiniband is the future of blade server backplanes. Incidentally, infiniband will also be supported by the advanced telecom computing architecture, a specification being developed by the PICMG that will support next-generation telco equipment and which Intel has identified as a key element in its own blade strategy. The specification will be ratified in September, all being well.

The scalability of these boards is unquestionable. Berndt Bischoff, vice president of sales at Fujitsu, claims one of its cabinets will be able to house 300 blades when it ships. IBM's eServer BladeCentre product is likely to provide 84 blades per rack when it ships. A lot will depend on the types of blades being shipped.

Few, if any, blade server vendors are currently offering dual-processor blades, although these will become available later this year - IBM expects to offer quad-processor symmetric multiprocessing blades early next year and will also be offering 64-bit Intel-based processor configurations along with blades based on its Power chip.

The right price
Perhaps the real issue here is availability. Little information is available on how many hours of uptime server vendors will be able to guarantee, but things will probably get better as they move away from the CPCI backplane, which uses a shared bus. Bischoff seems unsure about how reliable Fujitsu's servers would be because of a lack of disk mirroring, for example.

On the other hand, the sharing of multiple components through a common backplane lends more resilience to a system, argues HP's Franklin. Customers have three individual power supplies in a shared backplane, any of which can power any of the blades.

In spite of Franklin's availability claims, most, if not all, vendors will be positioning their blade servers at the lower end of the market. Bill Blundell, technical market development manager at Force Computers, certainly sees this as a key market. Force makes blade server equipment and sells it through OEM partners.

"A lot of Web servers are based around hardware that is difficult to scale," he says, adding that blade servers will solve this problem. The use of network load balancing and network address translation for aliasing machines to a single network address means that using dedicated servers rather than SMP-based boxes won't be a problem.

"Anyway, the cost of an SMP configuration alone puts it into a different order of magnitude," he says.

Pricing is a key selling point for these servers, according to Rebecca Jones, UK server marketing manager at Dell, which will launch its blade server later this year. Customers will break even when they buy their third blade for a chassis, she says, after which they will begin to see cost benefits.

Other uses for blade servers include terminal servers for thin client applications and even - bizarrely - ASPs, according to Bischoff. "The market will come back - it's still a viable business model for many applications," he says. "In a year from now, that market may begin to yield revenues."

He even vows that between ten and 15 per cent of Fujitsu's blade server revenue will come from the ASP market in two years' time.

"They can serve 300 customers with one big blade server," he enthuses. Given the fortunes of the ASP market in the past 18 months, few people will be holding their breath.

The low-end market positioning will continue for a while, at least until dual-processor and SMP-based blades appear. HP's Franklin also points out that it may be possible to cluster blades in a server, given the right management software. "The decision has been made from an HP perspective that the blade market is very embryonic at present and what customers will be doing is consolidating larger servers down to a smaller footprint, initially."

Low-end positioning doesn't mean channel partners can't make a healthy living out of this equipment, however. Steve Birch, head of marketing at IBM infrastructure partner Anix, is looking forward to selling IBM's blade server equipment when it becomes available.

Anix handles a lot of SAP implementations, and SAP uses a lot of application servers. The idea of putting lots of them in one rack attracts him. He sees cost saving as the main benefit for the moment.

"Take 16 servers and put them into one box - you could at least cut the cost of purchasing those by half," he claims. "Some of our customers have 150 servers or more. Imagine the floorspace they could save by having all those in one box and the ability to manage them all through a single area."

He doesn't believe the lower pricing will cause problems because the company makes most of its margin through consultancy rather than hardware, but it will give him a better proposal for his customers.

Birch believes blade servers will account for 30 per cent of his hardware revenue in two years' time. He doesn't think the blade server market will impinge on the rack-mounted server business too much, instead arguing that it will delineate the market further - because rack-mounts are more powerful than blade servers, there will still be a demand for them at the high end.

In his SAP scenario, for example, Birch sees SAP application logic running in a blade configuration, but back-end databases still serving the application from a rack-mounted server.

Clearly, blade servers are a new technology in the IT space, and while they won't always be powerful enough to replace all the servers in a data centre, they will nevertheless go some way towards rationalising the cabling spaghetti and reducing the footprint-per-MIP that conventional rack-mounts take up. The channel will be playing a waiting game this summer as it waits for vendors to ship their first blade servers. After that, it will be waiting for configurations to become more powerful. But the space and manageability gains will be worth waiting for.

Who's doing what?
- announced its blade server strategy on 26 April. It will be shipping its eServer BladeCenter systems towards the end of the year. The servers will use the company's Director management software and initial models will be Intel-based.

Dell - its passive backplane blade servers will be shipping towards the end of the year. The PowerEdge 1655MC will have up to six server blades in a single U enclosure, resulting in twice the density of today's 1U servers - the 'U' is a unit of measurement for the space taken up by a rack-mount of card server.

Fujitsu - announced the addition of a blade server to its Primergy range in March. It should have been shipped by the time you read this and will contain up to 20 server blades and two separate power supply modules.

Sun - plans to release products by the end of the year. It will be introducing a combination of Intel and Sparc servers, which will run Solaris and Linux. Intel and SPARC-based blades will be interchangeable between those servers.

HP - offers the bh3700 and bh7800 blade server chassis. The first is designed specifically to handle converged voice/data networks, while the latter handles other tasks, such as Web hosting, and can hold 16 cards. Either Pentium III or PA-RISC server blades are available from HP.

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