“There is no cloud, it’s just someone else’s computer”
1. Cloud computing – or “cloud” is a model for enabling ubiquitous network access to a shared pool of configurable computing resources (Wikipedia definition). Cloud computing is the delivery of shared computing resources, software or data — as a service and on-demand through the Internet. Cloud provides self-service capability, elasticity, automated management, scalability and pay-as you go service that is not inherent in virtualization.
Virtualization differs from cloud computing because virtualization is software that manipulates hardware, while cloud computing refers to a service that results from that manipulation.
Cloud can be private, public or hybrid. [Explain]
2. Virtualization – virtualization is software that separates physical infrastructures to create various dedicated resources. It is the fundamental technology that powers cloud computing. “Virtualization software makes it possible to run multiple operating systems and multiple applications on the same server at the same time. It enables businesses to reduce IT costs while increasing the efficiency, utilization and flexibility of their existing computer hardware. ”
The technology behind virtualization is known as a virtual machine monitor (VMM) or virtual manager, which separates compute environments from the actual physical infrastructure. Virtualization makes servers, workstations, storage and other systems independent of the physical hardware layer.
Some commercial hypervisors:
KVM – a Linux based open source hypervisor. First introduced into the Linux kernel in February 2007, it is now a mature hypervisor and is probably the most widely deployed open source hypervisor in an open source environment. KVM is used in products such as Redhat Enterprise Virtualization (RHEV).
Xen/Citrix – An open source hypervisor which originated in a 2003 Cambridge University research project. It runs on Linux (though being a Type 1 hypervisor, more properly one might say that its dom0 host runs on Linux, which in turn runs on Xen). It was originally supported by XenSource Inc, which was acquired by Citrix Inc in 2007.
VMware/vSphere-ESXi – is not a hypervisor, but the name of a company, VMware Inc. Our experience with VMware involves its vSphere product. vSphere uses VMware’s ESXi hypervisor. VMware’s hypervisor is very mature and extremely stable.
Hyper-V – Hyper-V is a commercial hypervisor provided by Microsoft. Whilst excellent for running Windows, being a hypervisor it will run any operating system supported by the hardware platform.
3. SAAS – Cloud application services, or Software as a Service (SaaS), represent the largest cloud market and are still growing quickly. SaaS uses the web to deliver applications that are managed by a third-party vendor and whose interface is accessed on the clients’ side. Most SaaS applications can be run directly from a web browser without any downloads or installations required, although some require plugins.
Because of the web delivery model, SaaS eliminates the need to install and run applications on individual computers. With SaaS, it’s easy for enterprises to streamline their maintenance and support, because everything can be managed by vendors: applications, runtime, data, middleware, OSes, virtualization, servers, storage and networking.
Popular SaaS offering types include email and collaboration, customer relationship management, and healthcare-related applications. Some large enterprises that are not traditionally thought of as software vendors have started building SaaS as an additional source of revenue in order to gain a competitive advantage.
4. PAAS – Cloud platform services, or Platform as a Service (PaaS), are used for applications, and other development, while providing cloud components to software. What developers gain with PaaS is a framework they can build upon to develop or customize applications. PaaS makes the development, testing, and deployment of applications quick, simple, and cost-effective. With this technology, enterprise operations, or a third-party provider, can manage OSes, virtualization, servers, storage, networking, and the PaaS software itself. Developers, however, manage the applications.
Enterprise PaaS provides line-of-business software developers a self-service portal for managing computing infrastructure from centralized IT operations and the platforms that are installed on top of the hardware. The enterprise PaaS can be delivered through a hybrid model that uses both public IaaS and on-premise infrastructure or as a pure private PaaS that only uses the latter.
5. IAAS – Cloud infrastructure services, known as Infrastructure as a Service (IaaS), are self-service models for accessing, monitoring, and managing remote datacenter infrastructures, such as compute (virtualized or bare mental), storage, networking, and networking services (e.g. firewalls). Instead of having to purchase hardware outright, users can purchase IaaS based on consumption, similar to electricity or other utility billing.
Compared to SaaS and PaaS, IaaS users are responsible for managing applications, data, runtime, middleware, and OSes. Providers still manage virtualization, servers, hard drives, storage, and networking. What users gain with IaaS is infrastructure on top of which they can install any required platform. Users are responsible for updating these if new versions are released.