Rising energy prices and the legislative focus on
environmental issues are forcing IT departments to look again at
power consumption and efficiency, putting the datacentre firmly in
the spotlight.
Research from IDC predicts that by 2008, datacentre users will
be spending more on power and cooling systems than on new server
technology.
It is important to realise that it is not only servers that
consume electricity. Between them, the ancillary technologies used
in the datacentre - air conditioning, storage devices, networking
controllers and, not least, uninterruptible power supplies (UPS) -
can consume just as much power as the actual servers
themselves.
UPS are arguably the mission-critical ancillary technology at
the heart of any business continuity and disaster recovery plan.
They provide emergency power in the event of primary power outages
and protect the core of an organisation's IT systems against power
surges.
David Bond, managing director of UK specialist Uninterruptible
Power Supplies Ltd, says, "At the end of the day, UPS systems just
supply electrical load. But by far the nastiest loads UPS have
historically had to deal with are blades.
The increased power density of blade servers has exposed UPS
systems that cannot cope. Now there is not an IT professional in
this market who would think of running IT systems without an
UPS."
Bond says users first became aware of UPS problems three years
ago with the growth of ultra-high-density racks of blade servers,
which deliver more processing power in less rack space, simplifying
cabling and reducing power consumption.
But as more equipment of greater density is packed into a small
space, temperature rises of up to 10 degrees are not uncommon, and
heat is the biggest threat to UPS battery life. As a result, heat
density is becoming a big issue in datacentres.
The largest and most mission-critical datacentres specify power
allocation and corresponding UPS safeguards to meet stringent
redundancy requirements that add to power consumption and its
regulation.
Redundancy is typically achieved though either an N+1 or a 1+1
design. In an N+1 design, also known as a parallel-redundant
system, multiple UPS modules are sized so that there are enough to
power the connected equipment (N), plus one additional module for
redundancy (+1).
During normal operation, the load is shared equally across all
modules. If a single module fails or is taken offline for service,
the UPS can continue to power connected systems.
In a 1+1 design, two UPS modules are sized so that either is
capable of carrying the entire load, which delivers improved
availability over N+1 systems. Some global enterprises even insist
on a 2N+1 datacentre architecture for complete peace of mind.
Rakesh Kumar, research vice-president at analyst firm Gartner,
says the power needed to drive a rack of high-density server blades
can be 10 to 15 times higher than in a traditional server
environment. He suggests that organisations carefully evaluate the
power protection requirements if they need to use the latest
servers.
"The best answer to the power and cooling issues is greater
design focus at the component level, coupled with the ability to
manage power at a high level," Kumar says.
"It will eventually be possible to implement systems that can
operate within targeted power and thermal limits, although many of
the components that will enable this kind of power management will
not arrive in the next five years."
UPS and back-up generators are increasingly designed to manage
the electrical noise degradation caused by the ever growing number
of smaller and smaller microprocessors and semiconductors contained
within servers.
Electrical noise can be caused by utility grid switching, as
well as common office equipment powered by mains electricity such
as lifts and photocopiers, and is the source of constant power line
disturbances.
If the automatic switching function between the UPS system,
back-up generators and utility grid source is not properly
configured, any lag can disrupt UPS to computer systems and cause
data loss, system lock-up and component failure.
UPS unit capacities have steadily increased. Manufacturer New
Wave launched a 40kW unit last year. By comparison, APC offers
66.7kVA (kilovolt amps - another way of rating maximum UPS load)
power modules, scalable to 1.6MVA.
New Wave claims its "transformerless" model is superior to more
traditional UPS designs. Surge suppression and filtering features
rely on in-built transformers, which themselves need power to
convert mains AC electricity to DC and back to AC again.
For example, a line-interactive UPS replaces the separate
battery charger, inverter and source selection switch of basic
units with a combined inverter/converter, which both charges the
battery and converts its energy to AC for the output as
required.
AC utility electricity is still the primary power source, and
the battery is secondary. But when utility power is operating, the
inverter/converter charges the battery, operating in reverse if the
power fails.
Supplier Liebert recommends users steer clear of
line-interactive UPS systems for mission-critical applications.
Liebert claims that line-interactive UPS units are generally only
85% effective against power anomalies, and have less protection
against surges, harmonics and frequency variations.
In high-speed networks, some Liebert customers have found that
in going to battery, line-interactive UPS systems drop loads,
resulting in data loss. The use of double-conversion online UPS
systems ensures continual power conditioning and maximum protection
against even daily power anomalies.
Villazim Xhiha, chief executive of New Wave, says online,
transformerless UPS technologies give a lot of advantages in terms
of power efficiency, management, size and compactness.
"They generate less harmonic noise disturbance that can affect
other power consumption in the datacentre. And our remote
monitoring facility which goes live early this year will supply
added peace of mind," Xhiha says.
New Wave has begun fitting some of its UPS units with in-built,
networked power monitoring tools. When connected to a customer's
own management systems or those hosted by the supplier, these tools
can provide proactive maintenance of power fluctuations and
switching capacity.
APC is a major supplier of UPS equipment in the UK (along with
Uninterruptible Power Supplies Ltd, Cholride, Gutor and Liebert),
and argues that the technology already exists to provide near-100%
availability of computing power.
The company claims that the key to fine-tuning UPS power
requirements is maintaining clear datacentre standards to achieve
predictable behaviour with high-density loads. APC calls for
clearer definitions of datacentre power requirements to help with
the design and installation of power and cooling equipment to
ensure UPS capacity is right-sized and maximises electrical
efficiency.
Paul Tyrer, APC managing director for UK and Ireland, says
traditional datacentres have been designed with only 50% extra
capacity built in to provide room for 10 years' worth of added
demand.
"IT and facilities must be able to factor into their delivery
requirements about a 14% increase in datacentre power each year,"
Tyrer says. "But that adds up to a compound growth rate well above
the maximum capacities built into many traditional datacentres.
"We are seeing customers come to us to talk about UPS much
earlier in the datacentre specification process nowadays as a
result. We tell our customers not to design for year 10 any more,
but to build capacity in for the here and now because the modular
power and cooling products available in the market today are easily
scalable and flex to growing demand, allowing organisations to
deploy technology as they grow and not 'just in case'."
The modular evolution of UPS units follows the trend towards
scalable blades that can be quickly hot-swapped or added as more
computing capacity is needed.
Increasingly, just blades are held in purpose-built housing or
racks that contain all the connectivity and networking components
required, so the trend within power and cooling has been to build
corresponding frames around these blade racks to control and
monitor heat with inbuilt air conditioning, as well as to house the
UPS units and batteries for greater redundancy.
Tyrer says APC has been physically housing modular UPS hardware
in the same rack space as the servers they protect for eight years
- since the introduction of its Symmetra unit.
Nowadays, the supplier is putting its weight behind its
Infrastruxure range, which organises access, cables, power and
cooling all in one unit around the server farm.
"While the industry tends to look at server statistics first in
the datacentre, the attach rate of such modular power protection
products is high, as disaster recovery and business continuity
plans come under consumption and efficiency focus," Tyrer says.
There are other simple housekeeping tasks a datacentre manager
can usefully perform, such as making sure UPS batteries are
properly charged and alternative power sources are on assured
standby.
But ultimately, says Chris Dean, managing director of datacentre
consultancy DMW, businesses need to test the UPS component of their
computing infrastructure for the future.
"They need to 'pull the plug' to make sure their business
continuity plan works. It has to be done very carefully and takes a
lot of planning but it is the only way to ensure you are protected.
At the same time, businesses need to look at how they can conserve
energy used by IT," says Dean.
IT managers can do this from the ground up, by looking at
environmentally friendly ways to build the datacentre.
Judging by how key UPS requirements are in today's IT
environments, a business may pay a high price for overlooking
it.
More information:
Datacentres losing their cool
How to avoid datacentre downtime
UPS FAQs
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