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Blade servers cut a new trail
Blade servers go beyond just saving shelf space to offer
corporates long-term benefits in maintenance, scalability, redudancy and server
management, says Jyothi Satyanathan
Business is getting more competitive and margins are getting thinner. To keep
costs down, many organisations have begun consolidating servers into centralised
data centres—using rack-mounted servers in many cases—as a means of
reducing the challenges and costs associated with administering many small servers
scattered across the enterprise.
Blade server technology addresses gaps in rack-mounted architecture with new
capabilities and features that improve usability while reducing costs. According
to the Clipper Group, the funny thing about blade servers is this: If done right,
it’s not what you do with them that defines the value proposition, it’s
what you, as an enterprise, don’t have to do that makes the proposition
so attractive. Let’s take a look at what they mean.
Defining blade servers
Until recently, physical server consolidation generally involved replacing bulky
tower servers with slender 1U or 2U rack systems. They take less space and put
servers and infrastructure within easy reach of the administrator, rather than
spread across a large campus. These servers enable organisations to reap many
benefits of consolidation, yet because each server requires its own infrastructure,
including power, networking and switching, they offer challenges of their own.
The term blade server refers to a chassis that can hold a number of hot-swappable
devices called blades. A server blade is an independent server, containing one
or more processors and associated memory, disk storage and network controllers
and running its own operating system and applications.
It is a type of rack-optimised server but one that eliminates many of the complications
of rack systems as common infrastructure components—such as power supplies,
fans, CD-ROM and floppy drives, Ethernet and Fibre Channel switches and system
ports—can be shared. The most visible difference is the vertical format
of blade servers, which are then mounted in a horizontal chassis, compared to
horizontal servers stacked vertically in typical rack systems.
Talking dollars and time
In the IT industry, the business case for any new investment today must be based
on sound return on investment (RoI) and total cost of ownership (TCO) justifications.
The beauty of blade servers is that there are several ways in which they can
save enterprises money versus tower and traditional rack servers.
For a start, blade servers eliminate the need to purchase excess processors
up front to provide for expansion room. Enterprises can buy what they need today,
and plug in another blade when their processing needs increase, thus spreading
the cost of capital equipment over time.
Because of increased rack density, fewer racks would be required to house servers,
which often results in lower rental charges from reduced floor space requirements.
The use of low-power processors in some blades can save money on electricity
and cooling costs too.
Another benefit that comes up over and over again as enterprises compare traditional
rack systems with blade servers is this: the common shared infrastructure. First
and foremost, this means a lower initial purchase price, which could result
in very significant savings in data centre environments by eliminating the cost
of hundreds or even thousands of cables.
A certain amount of assembly is needed to install each and every rack server,
from installing rails to mounting the server into the rack, to connecting all
the cables and perhaps reconfiguring the hierarchy of KVM switches and PDUs
needed to tie everything together. With a blade server, it is as simple as unpacking
it and sliding it into the chassis. In data centres with large numbers of servers
to install, this can add up to many hours of time and many resources saved.
By reducing the number of components in a rack from hundreds to a handful, the
number of points of potential failure are reduced as well. Fewer failures mean
less time spent servicing servers.
Scalable performance at will
One advantage blade servers share with 1U rack servers is the range of processors
they can support within the same chassis.
How does this help? For a start, it provides customisable performance, depending
on the application workload allocated to each blade, so that enterprises get
the level of performance they need and at the same time, enjoy upfront savings
in capital costs (from lower-end processors) as well as lower utility bills
on an ongoing basis. The ability to support a mix of blades containing different
types and speeds of processors today, and hotter, faster processors in the future,
provides investment protection as technology evolves.
Because blade servers are designed to efficiently scale out, multiple form factors—the
most common being 3U, 6U and 7U and containing varying numbers of blade bays
are available. A larger chassis that allows for greater expansion through option
modules helps to balance performance versus density to properly leverage infrastructure
for optimum utilisation.
Server blade designs also include high-availability features such as redundant
and hot-swap components, and even the hot-swapping of entire blades themselves.
Removing a server for maintenance simply involves sliding a blade out of the
chassis, much like removing a hot-swap hard disk drive. This makes implementing
a policy of hot-spare servers simple and effective. Like other types of servers,
blades can be configurable to fail over to one another.
Advanced blade servers can be designed to an even higher level of availability
so that there is no single point of failure. Memory protection methods more
sophisticated than standard ECC, as well as built-in RAID 1 mirroring for operating
system fail-over can be employed. All critical components can be redundant and/or
hot-swappable, including the cooling systems, power supplies, Ethernet controllers
and switches, mid- or backplanes, hard disk drives and service processors
Software plays its part
In some blade server designs, integrated systems management processors with
built-in intelligence make it simple to monitor and manage the status of blades,
the chassis and the integrated switches all at once.
Advanced management functions include concepts such as bay profiling: When a
blade is inserted into a profiled server blade bay, the system can automatically
load the operating system and application image designated for that bay onto
the blade and get the server up and running without any human intervention.
Likewise, hot spare blades waiting in bays can be re-purposed under software
control to replace failing blades or to handle peak loads.
Autonomic software can boost administrator productivity and reduce skill-level
requirements, which can help reduce costs, improve overall productivity and
make administration easier.
Conclusion
What customers want in any server is scalability, versatility, performance,
availability, easy serviceability, simple systems management and deployment,
as well as cost savings. Blade server architecture offers all this and more.
The author is country manager – xSeries and Intellistations, IBM India.
He can be reached at sjyothi@in.ibm.com
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