To begin, it’s important to acknowledge that cloud is a vague term. Organisations often talk about 'moving or migrating to the cloud' as though it is a journey to a set destination. However, without context, it can be challenging for people to understand. The traditional method of delivering services - from our servers, in our datacentre - provides a tangible context that isn’t available when thinking about public cloud services. To remove this vagueness, it’s initially useful to understand where cloud services are delivered from.
How do public cloud service providers deliver services?
As with any computing services, cloud services run on physical compute, storage and network hardware in a datacentre. The hyper-scale cloud service providers operate their compute resources from groups of vast, dedicated datacentres at strategically selected locations around the world, named regions. These locations are carefully selected based on a number of criteria, including: proximity to renewable energy sources and population centres, and the level of geographical and geopolitical stability.
Below is a map that shows the global regions of the hyper-scale cloud providers (as at 2016).
From the perspective of the consumer, the complexity of operating this vast global infrastructure of datacentres, servers and services - generally referred to as their cloud platform - is the responsibility of the cloud provider. Cloud platforms abstract away much of the complexity of running services and workloads for the consumer, leaving them to focus on their own services and workloads. The consumer does not need to understand how the cloud service is run, but simply how to use it.
Consumers interact with the cloud platform through a web-based management portal, or a command-line interface, which enable you to provision services and infrastructure (such as virtual servers or databases), view billing information, configure billing and reporting, etc.
The characteristics of public clouds
It is also useful to understand the characteristics of cloud services.
- on-demand self-service: you can self-provision computing capabilities without interaction with the provider. These activities are completed remotely over the internet using a web browser or command-line interface
- broad network access: the services are available over the internet, or through a direct private connection
- rapid elasticity: you can quickly scale provisions without the need for time consuming purchase of hardware, or the provision of new virtual machines
- measured service: cloud systems can automatically control and optimise resource use by leveraging a metering capability. Resource usage can be monitored, controlled and reported to provide transparency of service utilisation
- resource pooling: The provider’s resources are pooled to serve multiple consumers using a multi-tenant model
Examples of resource pooling:
- virtual servers share the same underlying host but are isolated from one another
- data and document storage services share the same underlying storage system, but customers’ data are securely isolated
- web-based services run on the same underlying infrastructure, but the workloads are completely isolated
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