Infrastructure as a Service

Infrastructure as a Service (IaaS) refers to the fundamental building blocks of computing that can be rented: physical or virtual servers, storage and networking

Platform as a Service

Platform as a Service (PaaS) is the next layer up – as well as the underlying storage, networking, and virtual servers, this layer also includes the tools and software that developers need to build applications on top, which could include middleware, database management, operating systems, and development tools.

Software as a Service

Software as a Service (SaaS) is the delivery of applications as a service, probably the version of cloud computing that most people are used to on a day-to-day basis. The underlying hardware and operating system is irrelevant to the end user, who will access the service via a web browser or app; it is often bought on a per-seat or per-user basis.

SaaS is the largest chunk of cloud spending simply because the variety of applications delivered via SaaS is huge, from CRM such as Salesforce, through to Microsoft's Office 365. And while the whole market is growing at a furious rate, it's the IaaS and PaaS segments that have consistently grown at much faster rates, according to analyst IDC: "This highlights the increasing reliance of enterprises on a cloud foundation built on cloud infrastructure, software-defined data, compute and governance solutions as a Service, and cloud-native platforms for application deployment for enterprise IT internal applications." IDC predicts that IaaS and PaaS will continue growing at a higher rate than the overall cloud market "as resilience, flexibility, and agility guide IT platform decisions".

Desktop as a service

Desktop as a service, or DaaS, is a cloud computing offering that securely delivers virtual apps and desktops from the cloud to any device. This managed desktop virtualization solution aka DaaS is used for provisioning secure SaaS and legacy applications as well as full Windows-based virtual desktops and delivers them to your workforce. With a predictable pay-as-a-go subscription model, DaaS makes it easy to scale up or down on-demand. It’s easy to manage and simplifies many of the IT admin tasks of desktop solutions.

Advantages

1.Best use of space: the fewer physical devices installed, the greater the availability of space in racks.

2.Support for legacy applications: when a company decides to migrate to a new operating system, you can keep your old operating system running in a virtual machine, which reduces the cost of migration.

3.Reduction of personnel costs, power, and cooling by using less physical equipment.

4.Better utilization of hardware – the hardware sharing by virtual machines is reduced to idle equipment.

Disadvantages

1.when the server goes offline, all the websites hosted by it will also go down.

2.Management – virtual environments need to be instantiated (create instances on virtual machines), monitored, configured and saved.

3.When several virtual machines are running on the same host, performance maybe hindered if the computer it’s running on lacks sufficient power.

4.Great use of disk space, since it takes all the files for each operating system installed on each virtual machine

Fat clients – regular desktop computer or laptop
Thin clients – computer has a regular OS but comparatively little computer power
Zero clients – dumb terminal or ultra-thin client does not have an OS and just provides a user interface (keyboard, mouse, monitor) and network connection with enough software to load the virtualization program

Server-side virtualization is delegated to a third-party service and resources are accessed via the Internet
Different types of cloud computing:

Infrastructure as a Service (IaaS) – provides servers and storage for the client to use as needed

Platform as a Service (PaaS) – provides servers and OS but customer installs applications

Software as a Service (SaaS) – provides hardware, OS, and applications

Personal computer provides virtual environments for applications using three possible methods:

Presentation virtualization – remote application on a server is controlled by a local computer (Remote Desktop Services is an example)

Application virtualization – a virtual environment allows an application to run independent of the host operating system

Client-side desktop virtualization – software installed on a PC manages virtual machines, each VM has its own OS installed (Virtual PC, VMWare Player, and VirtualBox are examples)

Client-side virtualization enables users to run VMs on their local computer.

It allows users to test new operating systems, software, or to run older software.

Host computer – the physical computer controlled by a user.

Host OS - the operating system of the host computer.

Guest OS - the operating system that is running in the VM.

Electricity usage accounted for by computers and electronic gadgets is soaring.

If left unchecked recent strides in power savings will be lost.

Even though many items have become more efficient over time the recent demand for electronics and their use has skyrocketed.

This increase in power usage can impact greenhouse gas emissions and power supply needs.

There is also a huge increase in electronic waste (e-waste) that needs to managed in order to keep the environment clean and safe.

Green computing is important because it is helping to minimize the energy used in computing by educating consumers on efficient ways to keep power usage low, by creating more economic electronics, and by encouraging safe and complete recycling.

Maximize energy efficiency during the product's lifetime.

Promote recycle ability or ability of defunct products and factory waste.

a) System Unit

Using technology from portable computers:

- Uses an energy-saving microprocessor.

- Employs microprocessor and hard disk drives that shift 
  to an energy-saving or sleep mode when not in 
  operation

b) Display

Displays have been made more energy efficient by using:

 - Flat panels that require less energy than the traditional 
   monitors.
 - Special power-down monitors that automatically reduce 
   power consumption when not in use.

c) Manufacturing

Computer manufacturer are using fewer harmful chemicals in production.
Particular attention is given to chlorofluorocarbons (CFCs) in solvents and cleaning agents.
Toxic nickel and other heavy metals are being eliminated or reduced in the manufacturing processes.

Green use — reducing the energy consumption of computers and other information systems as well as using them in an environmentally sound manner

Green disposal — refurbishing and reusing old computers and properly recycling unwanted computers and other electronic equipment

Green design — designing energy-efficient and environmentally sound components, computers, servers, cooling equipment, and data centers

Green manufacturing — manufacturing electronic components, computers, and other associated subsystems with minimal impact on the environment.

a) Conserving Energy

Hibernate your computer: configure your computer to “hibernate” automatically after 30 minutes or so of inactivity. Allowing your computer to hibernate saves.
Sleep mode use less energy: enables the “sleep mode” features on your computer, allowing it to use less power during period of in activity.

b) Recycling

Paper
Computer boxes
Packaging materials
Printer cartridges

Plastic that are part of computers are hard to isolate and recycle.

CRTs (cathode ray tubes) are found in older monitors usually contain enough lead and mercury.

Batteries contain acids that can burn or hurt body parts.

Buy electronics that are designed with saving resources in mind

Check with the manufacturer to see if it has a recycling program