ASHRAE Journal - February 2014 - 59

COLUMN DATA CENTERS

4. It had too much debt; and
5. It over-invested in music sales.
The article concluded by saying "But the reality is that
people are increasingly turning to digital books." Time's
conclusion is consistent with Andreessen's Wall Street
Journal article. Andreessen went on to say,
Software is also eating much of the value chain of
industries that are widely viewed as primarily existing in the physical world. In today's cars, software
runs the engines, controls safety features, entertains
passengers, guides drivers to destinations and connects each car to mobile, satellite and GPS networks.
The days when a car aficionado could repair his or
her own car are long past, due primarily to the high
software content. The trend toward hybrid and electric vehicles will only accelerate the software shift
-electric cars are completely computer controlled.
And the creation of software-powered driverless
cars is already under way at Google and the major
car companies.*

* Centrally managed: Network intelligence is (logically)
centralized in software-based SDN controllers that maintain a global view of the network, which appears to applications and policy engines as a single, logical switch.
* Programmatically configured: SDN lets network
managers configure, manage, secure, and optimize
network resources very quickly via dynamic, automated
SDN programs, which they can write themselves because
the programs do not depend on proprietary software.
* Open standards-based and vendor-neutral: When
implemented through open standards, SDN simplifies
network design and operation because instructions are
provided by SDN controllers instead of multiple, vendorspecific devices and protocols.

Software-Defined Data Centers

VMWare's CTO Steve Herrod is credited with developing the term "software-defined data centers (SDDC)":
"Compute, storage, networking, security, and availability
services are pooled, aggregated, and delivered as software,
and managed by intelligent, policy driven software."
In recent years, Software-Defined Network (SDN) has
EMA analyst Torsten Volk describes SDDC as enabling
become popular. Essentially, this is a programmable net- "...control all aspects of the data center - compute, network that creates flexibility and reduced dependence on working, storage-through hardware-independent manhardware upgrades for network upgrades.
agement and virtualization software."
Gartner analyst Dave Cappuccio commented in his
Software-Defined Network (SDN)
blog "Software Defined Data Centers-Hype or Reality?"
Open Networking Foundation defines SoftwareSometimes called the Virtual Data Center, the idea is
Defined Networking (SDN) as an emerging architecthat in a perfect world data center resources would
ture that is dynamic, manageable, cost-effective, and
be placed where it made the most economic sense,
adaptable, making it ideal for the high-bandwidth,
and then the allocation and use of those resources
dynamic nature of today's applications. This architecture
could be controlled by rules and analytics, allowing
decouples the network control and forwarding funcboth workflows and workloads to be moved/directed
tions enabling the network control to become directly
where they best served the business at any particular
programmable and the underlying infrastructure to
point in time (e.g., year-end processing, business
be abstracted for applications and network services.
continuity, disaster avoidance, time zones, etc.).
The OpenFlow™ protocol is a foundational element for
And in a true SDDC environment the physical data
building SDN solutions.
center location (and ownership) become irrelevant,
The SDN architecture is:
which means that true Hybrid Data Centers will
* Directly programmable: Network control is directly
emerge-allowing perhaps critical work on premprogrammable because it is decoupled from forwarding
ises, non-critical off-premises, and load or time
functions.
sensitive in the cloud.
* Agile: Abstracting control from forwarding lets
administrators dynamically adjust network-wide traffic
Software is a much more dynamic entity than hardflow to meet changing needs.
ware. However, the symbiotic relationship between the
*Used with permission from The Wall Street Journal, WSJ.com. Copyright 2011 Dow Jones & Company, Inc. All rights reserved.
FEBRUARY 2014

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