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.
www.picmg.org/compactpci.stmwww.fujitsu.comwww.fibrechannel.comwww.picmg.orgwww.hp.co.ukwww.dell.co.ukwww.anix.comWho's doing what?
IBM - 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.