The IaaS elements deliver what their name suggests – the enabling technologies for cloud computing, delivered as a service in a pure cloud environment or delivered through remote hands/smart hands support to colo customers using their own equipment.
The facilities layer provides the “home” for the hosting/cloud service (see where clouds live for more information). This is an essential, though oft-overlooked, part of the puzzle.
The network layer includes all the internal and external elements needed to build a complete networked platform: firewalls (hardware or appliance-based), load balancers, Internet VPN access and/or private WAN connectivity.
The storage layer provides all the enabling technologies – spinning disks or solid-state drives, SAN, snapshotting, management, etc – that is used to store customer data and to enable value-adding services like managed backup and disaster recovery.
The server layer provides the compute resources necessary to enable the applications and services that are being hosted. In a cloud-based solution, the servers are “hidden” from the customer, who rents virtual machines only. The physical servers normally consist of large chassis-based blade server platforms.
The virtualisation layer is at the heart of cloud computing services. In short, virtualisation software is used to allow multiple virtual machines (VMs) to be built on each physical server offering significant scalability, elasticity and resilience advantages. A hypervisor sits across the physical servers providing configuration, deployment and management of the VMs, along with high availability and multi-zone backup configurations.
Operating System Layer
The OS layer is the final piece of the IaaS puzzle. Once the VMs are architected for the customer (on either single- or multi-tenant hardware), they select the operating system of choice, e.g. Windows or Linux. The cloud provider also provides management, patching and upgrades for the OS. This completes the picture for “classic” cloud computing customers.