ASHRAE Journal - May 2014 - 96

Column Data centers

©DLB ASSociAteS conSuLting engineerS

business. These needs will vary greatly from company
Another example of software that is more predictto company and business to business. This requires a
able, less frequently changed, and more consistent on
commitment to develop and apply efficient methods
workload is firmware. One way to describe firmware is
to understand the business needs and the needs of
software that is programmed into chips and usually persoftware.
forming basic instructions. A practical way to think of a
More often than not, software is also in the position to
device that is firmware controlled is a typical TV remote
support business needs rather than being the core busi- control. Some other examples would be digital watches,
ness, but, of course, that is not always true.
digital cameras, consumer appliances, computer
Fundamental to solving any problem is to break the
peripherals, mobile phones, etc.
problem down to where each piece can then be underFirmware is held in non-volatile memory devices such
stood individually and then collectively.
as ROM, EPROM, or flash memory. Device firmware may
The rest of this article seeks to break down the over- rarely change during the device's lifetime. Again, this is
all topic of software into pieces and continue with
another example of a workload that is less volatile.
the theme of taking liberty to use
Figure 1 Hardware, system software & application software.
Software Applications vs. Apps
words and definitions that might
What is the difference between
be considered too general or
an application and an app; is
imprecise about IT professionals,
one simply the abbreviation
but are ones that are valuable for
of the other or is it something
HVAC professionals to gain a betelse. What is the definition of an
ter sense of how to think about
applet and its abbreviation? The
software and its impact on the
definitions vary and are not relworkload.
evant to the HVAC perspective of
Within this context, a way to
software.
generally classify software into
One way to characterize "applitwo areas is: system software and
cation software" is to label it as
application software.
software and mobile apps.
System software includes operSince it is valuable to understand a workload proating systems and any programs that support applicafile and how fast it can change, it helps to think
tion software. Application software performs the work
about the profile of mobile apps. Mobile apps in this
needed by one or more users.
It also can be said that systems software creates hard- context can be described as software that takes a
short amount of time to develop and a short amount
ware access for application software (Figure 1). Often
of time to modify. This basically translates into
system software has a base workload overhead that is
the worst possible scenario from a "speed of load
independent of user applications. As a result, the base
workload overhead portion is more predictable. Within change" perspective.
this systems software context, the following are some
types of software that can fit this category and can rep- Virtualization
So where does virtualization fit into this discusresent an above trivial amount of workload:
sion? Virtualization would be described as system
* Network software including software defined netsoftware because it permitted a significant transforwork (SDN) and virtual private network (VPN);
* Cloud computing software including private, public, mation of applications from separate servers, and
their respective operating systems, to a single server
and hybrid clouds; and
running many different operating systems and their
* Security software, virus software, and spam filters.
Breaking things down like this provides a sense for why associated applications. This one-time transformation permits significantly more applications to
it is reasonable to consider systems software workload
to be far less fluctuating or variable than the workload of reside on a single server and hence achieve a much
higher CPU use.
many applications software.
96

ASHRAE JouRnAl

ashrae.org

M ay 2 0 1 4

ASHRAE Journal - May 2014

Table of Contents for the Digital Edition of ASHRAE Journal - May 2014