Infrastructure as a Service (Iaas)
IaaS is one of the three delivery methods of cloud computing (the other two are Platform as a Service and Software as a Service).
Infrastructure as a Service delivers compute, networking and storage as software on commodity hardware, typically rack-mounted servers that can be added as required to scale a cloud horizontally.
- Compute – virtual machines of different sizes, different number of CPUs and/or memory.
- Networking – software defined networking: networks, routers, switches defined in software that also provider networking services: Load Balancing, Firewalls, VPN etc.
- Storage - blocks of storage as virtual disks or for storing/retrieving files
These three components are managed using a dashboard, command-line interface or API.
Characteristics of IaaS:
- Elasticity: A user can provision (add) or de-provision (remove) cloud instances to scale their cloud up or down.
- Multi-tenancy: The cloud servers are hosted on a shared infrastructure. This means that your cloud instances co-exist on the same hardware as another user’s cloud instances. To understand multi-tenancy, think of an apartment building (or block of flats). The renters/tenants have their own apartment, but share an elevator or stairway, foundation and roof. The owner of the building rents out apartments as needed and is responsible for the plumbing etc while each tenant is responsible for their own furniture and interior decorations. Similarly: an IaaS customer is responsible for their own applications, the cloud provider is simply providing the infrastructure.
- User self-service: Users can create their own cloud instances/virtual servers, provision their own storage and networks. This is one of the most compelling reasons to use a cloud, users are not beholden to an IT organization to provision their infrastructure for them.
- Utility billing: The cloud provider will bill the cloud-user for the resources used. Infrastructure as a Service is akin to a utility company providing and billing for electricity, water and natural-gas. You share electricity with everyone on the power grid provided by the power station, and only pay for what you use.
- Virtual Machines: The servers, also called “cloud instances”, are delivered to customers as virtual machines. A virtual machine is a server or workstation, with operating system and applications that appears to the user as a physical server.
Infrastructure as a Service is typically offered in three forms:
- Private cloud also called on-premise
- Public cloud
- Hosted private cloud
An organization can build a private IaaS cloud and then provide infrastructure services to their internal departments or partners. To build a private IaaS cloud, you need virtualization software to run a hypervisor.
Examples of hypervisor software are:
- HyperV, VMware, XEN.
- KVM - Kernel-based Virtual Machine is available with most Linux distributions and as open-source software. Red Hat offers KVM virtualization.
Once you have a virtualization or hypervisor layer, then you need cloud software to provide the on-demand, user self service and elasticity features of cloud computing as a Service.
Examples of IaaS private cloud software are:
- Eucalyptus, Microsoft, VMware.
- OpenStack: OpenStack is open-source project with over 200 contributors.
Next….. Concepts and architecture of OpenStack