Keeping cool and saving money Keeping the datacentre cool is by richman6


									                                                          Another deciding factor is cost. The new low power
                                                          processors and memory are more expensive as vendors
Keeping cool and saving money                             look to recoup the costs of development and
                                                          production. So the financial decision doesn’t just
Keeping the datacentre cool is like chasing a             include the cost of power and cooling, but also the cost
constantly moving target. As newer equipment is           of acquisition. This is less than a quarter of the cost of
introduced into the datacentre, the temperature           a server over a three-year period, but the energy
balance and the energy consumption change. IT             savings must be carefully calculated.
and Facilities Managers need to work together to
keep things under control.                                It is not just about buying new hardware. Over time,
                                                          equipment gets upgraded and even when a server is
Striking the right balance between the cost and energy    replaced that does not mean it is no longer used. Often
required to cool the datacentre and run hardware can      a server replacement program brings in new hardware
be difficult. The measure of how efficiently you are      for the most demanding applications and reassigns
using energy in the datacentre is defined as PUE. An      older hardware to less difficult tasks.
efficient datacentre should have a value of 2, but what
does this mean?                                           The days of upgrading processors and memory are
                                                          long gone for most organisations. This is because the
To arrive at the PUE for your datacentre you take the     cost involved, especially in downtime and engineer
amount of power you are consuming and divide it by        time, usually outweighs the cost of buying a new
the power used to run equipment. If you are               server.
consuming 15MW of power but your IT equipment
only consumes around 5MW then your PUE rating is          Yet there are things that can be changed over time and
3. This is relatively inefficient and shows that too      which will have a significant impact on power and
much power is being wasted on cooling the                 cooling costs. Power supplies and fans are becoming
environment.                                              more efficient. There are also products that vendors
                                                          standardise across their entire hardware range. It is
As you reduce the power used to cool the datacentre,      worth looking at the replacement costs for some of
more power is released for hardware. But this             these units as they age.
increases the amount of heat that needs to be removed
and thus the cooling bill goes up. So what can you do     Cooling technology with fans has also taken a huge
to strike the right long-term balance?                    leap forward. The more efficient a fan is, the less
                                                          power is required to cool processors and memory. This
The first step is to consider what you are buying.        does not alleviate the problem of cooling the air once
Processors and high performance memory consume a          extracted, but it does create an immediate power
lot of power and require plenty of cooling. There are     saving.
low power versions of both processors and memory,
but they are often more expensive and have a lower        Management solutions like HP Insight Power Manager
compute capability.                                       allow you to set limits on the amount of power being
                                                          used by server and storage blades. This allows IT and
There is no simple answer as to whether it is more        Facility Managers to agree on how to match power
efficient to buy a powerful server with higher power      usage to cooling capabilities, especially where there is
and cooling requirements, or two lower power but          a limit on the amount of cooling available in the
more efficient servers. The application you are running   datacentre.
will often dictate what is required of the server, with
applications such as databases and financial or           Hitting any moving target is hard. And when that
scientific calculations requiring the maximum             target falls across two departments, IT and Facilities
processing capability. In comparison, servers running     Management (FM), it is especially challenging. Using
multiple virtual machines are able to                     lower power hardware and replacing less efficient
move their workloads around to make the best use of       components will help IT meet the restrictions placed
resources.                                                upon it by FM in terms of power and heat. Buying
                                                          energy efficient hardware may be more expensive
from an initial Capital perspective, but if IT is to help
reduce Operational Expense, it must be given the
necessary budget increases to buy the right hardware.
In the long term, it will pay off.

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