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A Rackspace White Paper – Autumn 2009
Summary
Organisations have never had so much choice about how to host their
applications.
From Dedicated to Shared Hosting, Private to Public Cloud, there’s an
abundance of buzzwords, and precious little straight talking.
The purpose of this guide is to cut through the jargon, and help buyers find a
solution that fits their needs. For more help making your choice, please contact
Rackspace – the home of Fanatical Support®
Executive Summary
Managed, or Dedicated Hosting
Managed, or Dedicated Hosting is most suited to organisations looking for high uptime guarantees, security,
the backing of a comprehensive support team and the ability to customise their environment. Organisations
with compliance requirements, such as ecommerce providers are often a good fit for Managed Hosting. As
these solutions are designed and built to meet individual customer specifications, they are suitable for most
businesses. The costs associated with managed hosting mean that these solutions are better for critical
systems, rather than discretionary or “nice-to-have” infrastructures.
Private Cloud
Private Cloud is a good match for organisations seeking uptime guarantees, security, support, customisation
and flexibility. Creating Virtual Servers containing pre-defined content from templates can help organisations
to scale swiftly, be more agile and react to market demands as they change. The ability to consolidate large
server farms and better utilise hardware is a proven route to significant cost savings, and may also assist
with corporate green initiatives in reducing CO2 emissions. While sometimes cheaper than Managed
Hosting, Private Cloud still carries a price premium as it runs on dedicated hardware, thereby making it
unsuitable for organisations with the very smallest budgets.
Public Cloud
Public Cloud is ideal for young businesses seeking uncomplicated IT hosting with minimal outlay and no
complicated contracts. The ability of most public cloud offerings to scale effortlessly is particularly attractive
for websites and applications that have either seasonal demand, or unpredictable traffic. However, the lack
of customisation and uptime guarantees or Service Level Agreements (SLAs) may prove to be a barrier to
some.
Another quite separate use of Virtual Servers hosted in the Public Cloud is for test and development of
applications and User Acceptance Testing (UAT). The flexibility for coders to create new Cloud servers in a
matter of minutes and to be billed only for what they use makes this attractive to any software development
organisation.
While quick to scale and priced attractively, the shared nature of Public Cloud may be unsuitable for more
sensitive applications and data, most typically in the enterprise, ecommerce and regulated sectors
Introduction
This document is intended to explain the differences between Dedicated, Virtual and Public and Private
Cloud hosting, and to enable the reader to make an informed decision that matches their business
requirements.
In recent years, use of Virtualisation has become the norm amongst most large national and international
businesses as they come to recognise the benefits that it can offer. This has helped drive businesses away
from dedicated solutions. At the same time, the need for virtualisation expertise has increased take-up of
Managed Hosting solutions, where the service provider offers a team of certified Virtualisation engineers to
set up, maintain and troubleshoot Virtualised infrastructures at a fraction of the in-house cost of hiring such a
team.
Virtualisation is also often the technology behind Cloud Computing, enabling Cloud Hosting suppliers to offer
scalable and cost effective Virtualised environments to their customers.
Overview of Hosting Services
Managed Hosting
Managed Hosting offers organisations the peace of mind of hosting on dedicated infrastructure, in highsecurity
data centres, backed by comprehensive SLAs and supported 24/7/365 by a dedicated team of
technicians and account managers. The main benefits of Managed Hosting include converting capex to
opex by leasing instead of purchasing hardware and software, increased levels of support and service,
having a dedicated account manager and team of support technicians at your service 24 hours a day and the
security of a SAS-70 Type II and ISO 27001 certified data centre with multiple redundant connections to the
Internet.
Dedicated Virtualisation And The Private Cloud
Dedicated virtualisation, or Private Cloud as it is sometimes called, is built on dedicated servers running
hypervisor software e.g.VMware, Xen or Hyper-V. The hypervisor software provides a very light-weight
Operating System specifically to enable virtualisation, allowing you to create multiple virtual servers on one
physical server. Each virtual server exists completely independently from the others, and works the same
way as a standard physical server. This allows much higher utilisation of the available CPU resources.
Private Cloud combines resource and budget optimisation with rapid scaling up or down, together with the
higher security, and improved reliability of a Managed Hosting Solution. As Private Cloud runs on dedicated
hardware, it is typically backed by comprehensive SLAs, dedicated account and support teams and
supported 24/7/365.
The Public Cloud
Public Cloud is often based on Virtualisation technology, and is always delivered on shared hardware (unlike
Private Cloud which is delivered on dedicated infrastructure). This means that hosting organisations can
provide Public Cloud services at a much lower price point than Private Cloud. Public Cloud is usually offered
with so-called “utility pricing”, meaning that customers pay only for the resources used, with the option of
paying per hour, day, week or month. That combined with the instant scalability of many Public Cloud
offerings (such as Rackspace Cloud Sites) makes it a very attractive proposition for hosting basic websites
and applications with unpredictable or seasonal traffic requirements.
How and Why do Organisations Use Virtualisation / Private Cloud?
Virtualisation, or Private Cloud, is most commonly used for server consolidation, or to significantly increase
flexibility of an IT infrastructure. The greater security and robustness inherent in a dedicated solution make
Private Cloud very attractive to enterprise organisations and ecommerce traders for their core business
operations, and for any application that would generally be regarded as “mission critical”. Hosting on
dedicated infrastructure also means that Private Cloud solutions can easily meet the compliance
requirements for PCI, SOX, etc. and will often result in higher uptime guarantees and better SLAs compared
to the shared infrastructure of Public Cloud.
Consolidation
Private Cloud solutions can help businesses rationalise their
server estate and ensure that all IT resources are used
optimally. It has long been accepted practice for organisations
to treat each internal department’s IT requirements separately,
thereby resulting in many under-utilised servers hosting single
applications or websites. Consolidating these using a Private
Cloud solution results in better utilised server hardware and
cost savings. Another consideration when investigating
consolidation using Private Cloud is that of corporate
environmental policy – reducing the number of servers used
also reduces the amount of power used and therefore can
count towards decreasing the corporate CO2 output.
In many cases, customers consolidating their server estate
with Private Cloud can achieve between 15-20% cost saving
chiefly as a result of reduced physical hardware footprint.
Flexibility
Private Cloud solutions usually allow you to create and delete virtual machines very rapidly, certainly much
faster than the lead-times typically quoted by hosters for deploying dedicated infrastructure. This can be very
advantageous in corporate environments, particularly when working on development projects or User
Acceptance Testing (UAT). The ability to swiftly create a virtual server from a template with specific settings
in a corporate IT environment is unique to Private Cloud, and can be invaluable to developers wishing to test
a new version of code. The flexibility of Private Cloud is also highly attractive for ecommerce sites and
applications that experience seasonal demand. As the busy period approaches, extra virtual servers can be
brought online at short notice to cope with the demand, without the additional cost and lead-time typically
associated with provisioning physical servers.
How and Why do Organisations Use Public Cloud?
There are many different reasons why a customer will be attracted to a Public Cloud solution.
Minimal Entry Costs
For any organisation with limited funding, Public Cloud has the benefit of zero or low up-front charges.
Massive Scaling
Public clouds have the benefit of immense scalability. Some public clouds (as with Rackspace Cloud Sites)
scale automatically in response to levels of traffic. Other solutions (e.g. Rackspace Cloud Servers and Cloud
Files) come with Application Programming Interfaces (APIs), to enable cloud resources to be provisioned
automatically by customer applications. Delivering applications and sites this way ensures that whatever the
load, the service is never impacted by demand – this use has been tested extensively by highly spiky sites
such as those promoting popular musical concerts and political blogs.
Test & Development
Another strong case for the Public Cloud is for software developers. Virtual servers on the Public Cloud can
be provisioned on-demand to enable code tests. Once testing is complete, the Virtual Machine, or VM, can
be deleted, and no further costs are incurred. This is a much more flexible and cost-effective approach than
has been possible previously with dedicated test & development infrastructures.
Static Content Archives and Rich Media
Cloud Storage is an extremely cost-effective solution for organisations that need to keep large volumes of
data, either as an internal archive (e.g. for document management), or as an internet resource (e.g. an
image library). Static content with undemanding performance requirements is ideally suited to cloud storage
because of the storage and bandwidth charges are so affordable.
What are the differences between Private and Public Cloud?
The greatest differences between Private and Public Cloud solutions are the levels of support available, the
costs, the extent to which the infrastructure can be secured, and the ability to customise your solution.
As Public Cloud is built on shared infrastructures, there is therefore a very limited amount of customisation
available. Equally, the information security consequences of a shared infrastructure may impact how or
whether Public Cloud is used with sensitive data. In contrast, Private Cloud, which is built on dedicated
servers and with dedicated network devices, can be customised to meet most requirements including
handling sensitive data.
Public Cloud is almost always cheaper as it is built on a shared infrastructure – many providers charge on an
hourly basis for their service, and some (including Rackspace) have no minimum contract length. This
makes Public Cloud a very attractive option for start-ups and businesses with limited funds.
Private Cloud solutions will usually have a dedicated account team supporting them, plus a team of certified
virtualisation engineers monitoring and maintaining the platform. In the case of Rackspace Private Cloud,
the account team is available 24/7/365 by telephone, email and an online ticketing system. Many Public
Cloud providers provide limited support by telephone or Internet chat, and often during business hours only
(although Rackspace’s Public Cloud offerings are all supported 7x24).
Key Differentiators between Public and Private Cloud
Private Cloud Public Cloud
Dedicated Server and Network Hardware? Yes No
Can meet compliance requirements, e.g. PCI DSS, SOX, etc.? Yes No
Hourly Billing? No Yes
Add and delete new server instances within minutes via web portal? No Yes
Customisable infrastructure? Yes No
Supports Microsoft SQL Databases? Yes Yes *
IDS / DDoS Mitigation available? Yes No
Dedicated account team? Yes No
24/7/365 support? Yes Yes **
Is monitoring available? Yes No
* Rackspace Cloud Sites supports Microsoft SQL, with database storage available in 100MB increments
** Public Cloud support is often limited to the infrastructure only and accessible via telephone or internet chat
Conclusion
Each of the technologies described above – Managed Hosting, Virtualisation, Public and Private Cloud -
meets a specific set of business needs. Their specific features mean that they should be chosen carefully -
they are not all equally suitable for every application, or for every organisation.
As Public Cloud offerings continue to evolve, additional applications will become available in the Cloud, and
hosters providing Dedicated or Managed and Public Cloud products will be able to combine the two to
provide a hybrid offering. This will enable organisations to host their core applications and data on dedicated
hardware and then burst into the Public Cloud to cope with increased demand more cost effectively. These
hybrid solutions are expected to become the norm in the course of the next decade.....................................................hhjkhjk...............................
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