I have 1 physical server, I have 1 logical server. I have 1 physical server, I have 10 logical servers.
Horizontal scaling is linear.
If your not an IT company, then SaaS is as much as you need.
They’ve a big inventory of services.
Jerry Horgan - Understanding Cloud Computing
A guide to understanding
• Cloud Computing
• Utility Computing
• Everything as a Service (?aaS)
So what is Cloud Computing?
• Its Virtualisation
• Its Utility Computing
• Its Software as a Service
• Its Platform as a Service
• Its Infrastructure as a Service
• Its ??? as a Service
• Its all about Services
So what isn’t Cloud Computing?
• A silver bullet
• 100% reliable - Don’t believe the hype
So what is virtualisation?
• It’s the abstraction of logical resources
from physical resources.
– And that means?
– Sizing the logical resources to the service
requirement rather than sizing the physical
resources to the service requirement.
Which brings us to Scaling
• Adding capacity to our service
– Promotions, one-off events (short-lived)
– Natural growth
• Horizontal vs Vertical scaling
• Scaling is traditionally vertical
– Vertical doesn’t scale linearly, more exponentially
• Think electricity
• Paying for computing resources
– Pay as you Grow / Go
– Provider worries about the back-end
as a Service
• Depends on your needs or where you
are in your IT application development
Software as a Service (SaaS)
• Provides a virtual environment for you
to deploy a service (application) in.
• Google Apps
• Or your website
• CRM Based Apps, Email, Call-Center
• €70 per person per month
• Email, Calendar and Office applications
• $50 per person per year
– Compare this to a PC, Email Server /
Hosting, and MS Office costs
• Even over 3-5 years
SaaS - Apps run in the cloud
• Applications / Documents available from
– Work from home or on the road
• You don’t require powerful desktops or
– Access devices can be much cheaper / smaller
Platform as a Service (PaaS)
• Provides a virtual server for you to
• This can be a Virtual Machine, a Virtual
Private Server (VPS) or some other
Amazon - Elastic Cloud
• The numero uno
Infrastructure as a Service (IaaS)
• Provides a complete network, data
storage and set of servers
– This usually comes from your ISP or Data-
Is it all out there in the ether?
• Private cloud vs Public cloud
– You can do both
• Virtual private cloud …
What tools can I use?
• Vmware ESXi http://www.vmware.com/products/esxi/
• Citrix XEN
• UEC http://www.ubuntu.com/cloud
• KVM http://www.linux-kvm.org/page/Main_Page
• VirtualBox http://www.virtualbox.org/
• How safe is your data in the cloud?
– Data protection, Discovery orders, FoI
• What happens when you loose your
– Do we need something better than DSL?
• That depends on our uptime requirement