Via @Interoute How to build a fast hybrid cloud for your online business

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How to build a fast hybrid cloud for
your online business

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NOVEMBER 2015 Copyright © 2015 Interoute Communications Ltd 2
Using hybrid cloud to match IT capacity with variable demand
It's a perennial argument, trodden over endlessly by analysts and vendors: private cloud, public cloud, or hybrid cloud?
The optimal choice today for most companies' IT requirements is hybrid cloud, and cases of 'pure private' and 'pure
public' are unusual. At one extreme there are companies and organisations whose operations require a degree of privacy
which can only be ensured by private IT systems, whether those are based on-premises or in a secure colocation facility.
The question of efficiently matching IT capacity to demand does not come into it. Or there are rare companies whose
demand for IT capacity is non-varying or otherwise highly predictable, so that long-term capital-based purchasing makes
sense. At the other extreme, you typically find the start-ups ('two guys in a loft') with an idea and few customers, yet. For
them, the zero-commitment entry point and pay-as-you-grow elastic scaling of public cloud is a natural fit. Six months
from now they might be millionaires, or no longer in business.
Online retailing is a good example of highly variable demand, due to the uneven patterns of customer purchasing through
the year. Most established online retailers experience a baseline demand that is continuous through most of the year,
while in the two to three months pre-Christmas period (in the USA, starting with another peak at the Thanksgiving
holiday) the demand can grow to five or ten times above the baseline. Similar smaller peaks happen around certain days
of the year, such as Valentine's day, Mother's day, or Father's day; which of those is most significant depends on whether
you are selling, say, chocolates or electronic gadgets. (Note that variability of demand for an established retail business is
highly predictable in timing, though less so in magnitude, whereas for those two guys in the loft their future demand
is unpredictably variable, thus leading to different private/public cloud balance points.)
Now one of the facts of online retail life is that the customer's expectations do not vary much: he or she expects a fast,
pretty much 'instant', response from a website whether it is 4pm on 24th December, or 4pm on 24th August. The website
has to respond quickly to the customer's clicks and key presses; if the product is virtual it has to be ready to download
within a minute or two. The retailer's only option is to scale its IT capacity to provide the responsiveness needed as the
demand grows, or risk losing business to the other companies operating in the same marketplace. Responsiveness is one
of those service details which in the end separates the average company from the exceptional company. A hybrid cloud
solution is a natural fit to these requirements: use private infrastructure for the continuous baseline demand, and public
cloud to handle the peaks of demand: 'own the base and rent the spikes' is a very neat summing-up phrase (see Joe
Weinman's book,Cloudonomics, page 167).
But another fact of life is that IT requirements change. Company goals change: expand market share in a current market,
expand business into new markets, withdraw from an unsuccessful market, and so on. Especially true in Europe where
markets are fragmented by language, culture and national boundaries. So hybrid solutions are not fixed for years at a
time but need to be adaptable to changing overall IT capacity and the balance of private versus public infrastructure in
use.
Commitment to a hybrid cloud solution obviously requires the use of at least several compute and/or data storage
locations (on-premises, private colocated, or public). Then, it requires high performance network connections between
the compute/storage locations. The desirable characteristics of network performance are fairly obvious to state:
• low latency
• high bandwidth
• reliable (performance does not vary)

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• required network performance available over wide geographical area (ideally from the same provider)
• predictable/simple costs
Latency is about physics and geography
Of all the factors that determine overall system performance, network latency is the factor that you usually have the least
possibility to change. It will be determined by the geographical locations of the compute/storage systems within your
hybrid cloud.
(What about CDN? Content Delivery Networks solve the latency problem for shared content. They basically provide a
huge distributed network of caching servers which create copies of an image or video in multiple locations so that users'
browsers can get that item more quickly, without going all the way to the original webserver. In the situations that I am
describing here the customer transactions are unique to each customer, so there is little shared content which CDN
servers can capture.)
Since data in optic fibres travels at the 'speed of light' it is simplistic to think that data travels 'instantaneously'. A good
working number for data transfers in an IT system is 5 microseconds per kilometre in a private network cable. But latency
is defined as a two-way (round trip) measure, hence 10 microseconds per kilometre. Over a 1000 km distance that makes
10 milliseconds. This is the physical limit, to which must always be added several milliseconds of time costs for encoding
and decoding of data packets, passage through network hardware, error correction for corrupted packets, and so on.
This level of time cost does matter for companies operating in European markets, and wanting to use hybrid cloud
solutions, because most public cloud providers have located their zones (data centres) in the North-western corner of
Europe (predominantly Ireland, the UK, and the Netherlands). The network latency from here to Spain and Italy, or
Eastern European countries, via the fastest private networks, is of the order of 20 to 25 milliseconds. This may seem fast,
but for a hybrid cloud system, it can be a significantly large number.
Interoute's IaaS cloud platform, Virtual Data Centre, has been designed differently, with distributed compute zones
located in North-west, East, Central and Southern Europe. The goal is to provide zones in the locations where companies
are operating, reducing the network latency in order to boost overall system performance.
Network latency and hybrid cloud responsiveness
For an online retailer, system performance is determined by the expectations of the customer. For a service delivered via
the web, the target response time for every customer interaction —the time taken between a 'send' action by the user,
and the appearance of a response in the web browser—is 200 milliseconds (0.2 seconds). More than this and the user will
start to experience a frustrating sense of delay. For more complex interactions involving upload or download of
documents or images, or completing an order, the customer's sense of delay will certainly be slower, but for any
particular case there will be a maximum acceptable response time for the customer.
So, at the front end, the system must respond to the customer fast enough, and there will be a network latency cost for
responding to the customer, via the Internet. To complete the response requires, at the back end, doing whatever
processing is necessary. For example, to deliver a customer's order could be a relatively simple matter of processing a
credit card and issuing a request to the warehouse, or a more complex task of creating content in real time (possibly

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interactively, with live editing by the customer), and being able to deliver it to the customer (for example, in an e-book
format) or feed it to a physical delivery system (for example, a printed book, or a set of photographic prints).
In a hybrid cloud, each single request by the user can involve multiple pull/push movements of data across the network:
retrieving customer details from a remote database, adding new content to a database, processing text or image in one
location and using the result in another location. Consider the case of a retailer operating private infrastructure in Spain,
using public cloud located in Amsterdam, via a private network inter-connection. Every data transaction will cost about 25
milliseconds. It is easy to see that given four or five transactions of 25 ms, and a customer response time of 200
ms, network latency can consume the major part of the total response time the system has to meet. All the more so since I
still need to add the network latency between the customer's computer and the front end web server, which involves use
of the Internet and a very wide variety of possible home/office network connections, thus the latency will be relatively
long, and very variable.
Reduce network latency and gain options for your business
To meet response time requirements, you will be squeezed to do more processing in less time within the data centre, or
to provision a more complex replicated database system to reduce the number of data transfers, either of which will have
recurring per-minute costs in larger numbers of CPU cycles, more memory and more storage (or faster and more
expensive storage). In online retailing, profit margins are usually set very tight, thus the costs difference between a
profitable and an unrealistic operation can be very narrow.
By taking away the time costs of network latency, such as with the distributed Interoute VDC platform, you can gain time
and options for your business. One option can be to reduce the costs of computing in your hybrid system, since less
compute and storage resources will be able to complete the task within the required time. Another option can be to use
your compute resources to do more with the greater time available, offering more to the customer and thus positioning
yourself more strongly in the marketplace.
Find out more
• PhotoBox.com prepares for seasonal peak demands by building on Interoute Virtual Data Centre
• How to improve cloud latency and throughput: How good is your cloud provider's network?
Interoute is one of Europe's largest network providers. Our cloud computing platform, Interoute VDC, can be inter-
connected with numerous network and unified communications services. We have the resources and expertise to deliver
flexible and cost-effective network solutions for hybrid cloud solutions for business, which can scale and adapt as
requirements change.
Contact us by email to discuss your cloud computing and network requirements.