Virtualization and Cloud Computing

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Date: Nov 5, 2022

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In this sample chapter from CompTIA A+ Core 1 (220-1101) and Core 2 (220-1102) Cert Guide, you will review common cloud-computing concepts and characteristics of client-side virtualization.

This chapter covers the two A+ 220-1101 exam objectives related to virtualization and cloud computing. These objectives may comprise 11 percent of the exam questions:

Cloud computing involves using remote servers in the Internet “cloud” to store, manage, and process data instead of using local servers or a personal computer. Cloud servers usually reside in large server farms, where powerful servers host thousands of virtual machines.

Remember that a computer is made up of hardware components that process software instructions. Virtual computing technology creates and runs multiple instances of software operating systems—such as desktops, servers, and even networks—on a single piece of hardware. Multiple software systems sharing the resources of one hardware system is known as virtualization. A single laptop, desktop, or server commonly is used to run two or more different operating systems, such as Linux and Windows 10, at the same time. Figure 4-1 depicts several different servers virtually running on one robust hardware machine.

Figure 4.1 One Hardware Machine Running Several Virtual Servers (Image © Zern Liew, Shutterstock)

Cloud computing involves using virtual machines in commercial data centers, to relieve customers of the expense of maintaining a network center. Cloud-based systems enable customers to pay for only the services and capacity they use, which allows businesses to grow their technology capacity as they need it and avoid high up-front costs.

“Do I Know This Already?” Quiz

The “Do I Know This Already?” quiz allows you to assess whether you need to read the entire chapter. Table 4-1 lists both the major headings in this chapter and the “Do I Know This Already?” quiz questions covering the material in those headings so that you can assess your knowledge of these specific areas. The answers to the “Do I Know This Already?” quiz appear in Appendix A, “Answers to the ‘Do I Know This Already?’ Quizzes and Review Questions.”

Table 4-1 “Do I Know This Already?” Section-to-Question Mapping

Foundation Topics Section

Questions

Common Cloud Models

1–5

Client-Side Virtualization Overview

6–10

CAUTION

The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you do not know the answer to a question or are only partially sure of the answer, you should mark that question as wrong for the purposes of the self-assessment. Giving yourself credit for an answer you correctly guess skews your self-assessment results and might provide you with a false sense of security.

1. Which cloud computing model allows companies to access software when they need it but avoid the expense of maintaining the software when they do not need it?

  1. Resource pooling

  2. Rapid elasticity

  3. On-demand

  4. Hybrid

2. You have been asked to arrange for your team to develop software in a cloud environment. Which of the following services will you seek as a solution?

  1. PaaS

  2. SaaS

  3. IaaS

  4. None of these options are correct

3. A company requires high security and high reliability for its network services. What type of cloud environment is likely to meet these requirements?

  1. Public cloud

  2. External cloud

  3. Internal cloud

  4. Infrastructure as a Service

4. Which of the following allows users to access remote applications and use them as if they were installed on their own machine?

  1. Application virtualization

  2. Sandboxing

  3. VMM

  4. File synchronization

5. What term describes a cloud provider’s capability to rapidly scale up and scale back computing resources as needed?

  1. Rapid elasticity

  2. Flex data services

  3. Virtual data flexing

  4. Expansive data services

6. Which of the following are used to create and run a VM? (Choose two.)

  1. Hypervisor

  2. VMM

  3. Emulator

  4. Virtual sphere

7. Which of the following is a reproduction of an operating system?

  1. Virtual machine

  2. VMware Fusion

  3. Emulator

  4. Hyper-V

8. Which operating systems can be guests on a VM?

  1. Windows

  2. Linux

  3. UNIX

  4. None of these options are correct

  5. All of these options are correct

9. Which of the following is true?

  1. A 32-bit system can host a 64-bit VM.

  2. A VMM can create only one operating system per hardware device.

  3. A 64-bit system can host a 32-bit system.

  4. Only one VM can run at a time on a workstation with one display.

10. Which of the following is true of the BIOS/UEFI when creating a VM?

  1. Hypervisors create their own BIOS/UEFI settings.

  2. The BIOS/UEFI firmware must support VMs.

  3. All BIOS/UEFI firmware supports VMs.

  4. A separate hard disk must be installed for each VM.

Common Cloud Models

220-1101: Objective 4.1: Summarize cloud-computing concepts.

The cloud refers to any type of computing—including program execution, storage, or services—that takes place remotely. Understanding basic cloud concepts is important for technicians, who will increasingly be asked to manage software or data in the cloud. Some of those functions are described in the following sections.

IaaS

Infrastructure as a Service (IaaS) enables customers to purchase access to data center infrastructure such as storage, network, and networking services. In this model, the cloud provider covers the costs and work involved in equipment, firewall configurations, and other maintenance. Thousands of companies are realizing that they can reduce the costs of their network infrastructure by outsourcing storage and computing services to a cloud provider. These include new startup companies that lack the capital resources to buy and manage equipment as they grow and established companies that want to reduce the costs related to backup and storage of their networks.

One key feature of IaaS is the flexibility it offers to customers, who can now just use the virtual resources they need when they need them instead of having to pay for them when they don’t need them.

IaaS puts users in charge of all the software used in a project, from applications and data to the operating system. IaaS vendors supply the hardware and network support tools.

Amazon first introduced cloud services in 2006, and the field of cloud providers continues to grow. At press time, the three largest cloud providers are as follows:

SaaS

Software as a Service (SaaS) refers to software that is hosted on servers and accessed through a web browser. Because SaaS processing is performed at the server, a thin client, smartphone, or tablet is sufficient to run the software. A browser-based service that does not require a user to download an application code to use the service is an example of SaaS.

Perhaps the best-known SaaS is Google Mail (Gmail). Gmail servers provide the Gmail service to anyone who has a web browser. Other examples of SaaS include the following:

SaaS is a cloud-based software licensing and delivery model that grants customers access to software on a subscription basis using the SaaS vendor’s servers. SaaS is designed for organizations that need to use a service rather than develop or deploy one. Figure 4-2 illustrates the word processor in Google Docs.

Figure 4.2 Using the Google Docs Word Processor to Create a Report from a Template, with Random Text as Placeholders

PaaS

Platform as a Service (PaaS) enables vendors to develop and deploy application software in a cloud environment. A developer using PaaS can concentrate on software features instead of possible issues with server hardware and operating systems.

Some of the major PaaS vendors include the following:

Many vendors provide many services across multiple platforms.

Note

Microsoft Azure is listed in both the PaaS and IaaS categories because it can be used in either role, depending on the services a user purchases.

Keep in mind the following considerations in selecting a PaaS vendor:

Public vs. Private vs. Hybrid vs. Community

Four general types of cloud computing are used. Each type can have variables in its implementation, depending on customer needs.

Cloud Characteristics

Cloud computing is a generic term that can encompass several different computer network models and features that serve a customer’s unique requirements. This section describes different ways a computer cloud can be designed and implemented to meet the computing and network needs of a company or institution.

Shared Resources

Shared resources refers to the practice of sharing equipment or data on a network to save costs. This is the most common reason for implementing cloud computing. The way clouds are designed and implemented can vary according to the customer’s needs. Devices and data can be shared over the Internet in two main ways: using an internal cloud or using an external cloud.

Internal Cloud

Internal and external clouds are defined by the ownership of the cloud’s resources. With an internal cloud, a company might need the flexibility of cloud services but also have security and guaranteed availability requirements that prevent the company from accessing cloud services outside its own network. An internal cloud is similar to a private cloud, but it is built and owned inside the organization. With an internal cloud, the company gets the virtualization services and flexibility of a commercial cloud, but with the security and reliability that comes from existing within the company’s network infrastructure. The cost of an internal cloud might be higher than the cost of outsourcing to commercial services, but sharing resources internally still reduces the cost.

External Cloud

An external cloud is a cloud solution that exists outside an organization’s physical boundaries. It can be private, public, or community based, as long as it is not located on an organization’s property.

Rapid Elasticity

Rapid elasticity refers to the capability to rapidly scale up and scale back cloud computing resources as needed. For example, selling high-demand concert tickets in the days before cloud computing often resulted in crashing servers and disappointed customers. Thanks to the rapid elasticity of the cloud, high-demand events can quickly expand capacity for online sales without leaving customers unserved when they try to buy.

High Availability

The cloud is always up and open for work. Providers maintain reliable service by replicating cloud servers in clusters within their data centers. This way, if one server crashes, other servers can pick up the work.

Another way providers ensure reliable high availability is to replicate entire data centers in different parts of a geographical region, or even across the globe. This model ensures that a customer’s computing services will not be disrupted by natural disasters such as earthquakes, fires, and storms. With global availability, customers can place their services closest to their customers around the world, to reduce access time to web servers and data.

File Synchronization

Storing, moving, backing up, and updating data can be a huge task for a company’s IT department. Cloud providers have designed file synchronization services to make replicating on-premises data synching to multiple sites both automated and reliable. AWS DataSync and Microsoft’s SQL Data Sync are two examples of this specialized service. These automated services allow companies’ IT departments to focus on other tasks.

On-Demand

On-demand is a shortened term for on-demand self-services. On-demand self-services from SaaS providers such as Salesforce.com, Gmail, and others are available to customers when they need them but do not need to be maintained by the customer when they are not needed.

Metered Utilization

Organizations purchase cloud computing services in much the same way as utilities such as gas, water, and electricity. With metered utilization, these services are measured in some way, and the price is based on the amount used. Cloud providers can base prices in different ways for different services. For example, cloud computing services are metered by the minute: The user pays only for the minutes used. Storage services are usually charged by the gigabyte. More complex cloud services, such as replication of servers to be used in different areas, charge by the instance of snapshots or other services.

Of course, cloud providers have many different pricing schedules. Three common ones follow:

Metered cloud services can mean immense savings for customers whose computing needs are periodic or uncertain, and their popularity accounts for much of the growth of cloud services. To save money, many companies are outsourcing their data center tasks to the cloud.

Desktop Virtualization

Desktop virtualization refers to creating a user interface to a computer that is hosted on a central server on-premises or perhaps in the cloud. Either way, the user experience with the virtual desktop is the same. When a company uses a vendor’s virtual desktop infrastructure (VDI), users can use minimally powered devices with an Internet connection and work as if processing were happening locally. Basically, VDI allows organizations to offer users remote access to virtual desktop environments from almost any device, such as a smart phone, tablet, or laptop. They can access this through client software installed on their local device or on a web browser.

Desktop virtualization is also known as thin client networking because the processing is centralized. Only mouse and keyboard inputs are sent across the local network for on-premises VDI or across the Internet for VDI in the cloud.

When a VM has an operating system installed, it appears and can behave like any other computer on a network. To interact with other machines, it needs to have a virtual network interface card (NIC) installed so that it can have a physical MAC address and an IP address. The virtual NIC behaves almost exactly like a physical NIC, but the administrator can use the virtual machine manager (VMM) to assign a specific MAC address. This is different from physical NICs with MAC addresses that are burned into the hardware by the manufacturer.

If administrators want the VM to communicate with other machines, they can create a path, or bridge, between the virtual NIC and the physical NIC on the VMM hardware. This allows the VM to communicate like any other machine in the LAN. In Hyper-V, this can be done by creating a virtual switch under the Virtual Switch Manager (see Figure 4-3).

Figure 4.3 Creating a Virtual Switch in Hyper-V

Client-Side Virtualization Overview

220-1101: Objective 4.2: Summarize aspects of client-side virtualization.

Microsoft (Hyper-V) and third-party vendors, such as Oracle (VirtualBox), VMware (VMware Workstation, VMware Fusion), and Parallels (Parallels Desktop), have offered virtualization solutions for some time. Virtualization enables a single computer to run two or more operating systems at the same time, using the same hardware resources.

To understand virtualization, make sure you understand these terms:

When creating a VM, a VMM/hypervisor sets aside memory space that provides access to virtualized storage, ports, video, and other hardware, as well as a hard disk image file known as a virtual hard disk (VHD and the newer VHDX). When the VM is created, the user specifies the type of operating system that will be installed.

After the VM starts, the user can install the operating system from an .iso image file or from physical media. After the operating system is installed, the VM detects and uses the virtualized hardware that the VMM set up.

The VMM/hypervisor can start and stop the VM and modify the virtual hardware that the VM has access to. For example, the VMM can adjust the amount of RAM that the VM uses, change the virtual network adapter that the VM uses, and specify what type of network access the VM has. If a VM malfunctions, it can be stopped and restarted without affecting the host device.

A computer can run a different operating system in two ways:

Several categories of virtualization exist: host/guest, hypervisor, server-hosted, and client-side virtualization.

Host/Guest Virtualization

In host/guest virtualization, a PC or workstation runs a standard operating system and a VMM that runs inside the host operating system; each VM is a guest operating system. Connections to hardware (networking, display, printing, and so on) are passed from the guest operating system, to the virtualization program, to the host computer’s operating system.

Figure 4-4 illustrates Oracle VM VirtualBox, a popular free host virtualizer. Other examples include Windows Virtual PC from Microsoft (for Windows 7), Microsoft Hyper-V (for Windows 8 and later), and VMware Workstation Player.

Figure 4.4 Oracle VM VirtualBox Manager Preparing to Start a VM

This type of virtualization is often used for client-side virtualization. However, client-side virtualization can also be centrally managed from the standpoint of the creation and management of VM images, although the images are being run locally.

Purpose of Virtual Machines

Software developers use virtual machines to develop applications and operating system enhancements. Three key ways developers use VMs are for sandboxing, test development, and application virtualization.

A common use for VMs is sandboxing, creating an isolated machine (or network of machines) where experiments can be run or software can be securely tested without risk to machines on the production network. For example, building and testing a new web server in a sandbox can be helpful so that mistakes happen before customers experience them.

The term sandboxing refers to a play area where children freely play with toys and sand inside a safe environment. Sandboxing is also a great way for students to learn new networking skills and try new code in an isolated, nonproduction environment where mistakes won’t result in expensive consequences.

Test development with virtual machines enables software developers to write and test computer applications. A key step in software development is seeing how code presents itself on a computer. This can involve trying several different scenarios, troubleshooting bugs that arise, and then tweaking the code. With virtual machines, a developer can capture different stages of development in snapshots and then try different tests and tasks to check performance. If the new code doesn’t work, they can easily revert to the last snapshot and try something else. Developers can also keep a library of different operating systems in one place, to test performance in different environments.

Application virtualization is the logical next step from hardware virtualization. Instead of installing applications on office computers, for example, users can install a desktop client that can access and manage application streaming from a company server located in a data center or in the cloud. The desktop client isolates the use of the streaming application from the user’s computer and any other applications in use. Basically, application virtualization allows users to access remote applications and use them as if they were installed on their own machine. This makes it easy to manage and maintain applications across an organization and enables different kinds of devices to access the applications, regardless of the device’s operating system or storage space.

Cross-platform virtualization is a type of application virtualization that can involve different underlying virtualization technologies. For example, the virtual software Microsoft 365 can be run across platforms as well as operating systems, so users on iPads, Linux devices, or macOS can have the same application software experience.

Legacy software and operating systems can be used in other types of application virtualization. Support specialists can run several legacy operating systems on one machine without rebooting their systems. These VMs are isolated, or containerized, so that they don’t interfere with other machines. Virtual machines even enable a single PC to run both 32-bit and 64-bit versions of the same operating system so that applications that run better in 32-bit mode can be run without the need for a separate computer. For example, in Figure 4-4, a 32-bit version of Windows 8 is virtualized but not currently running in the figure.

The virtual machines on a computer can perform different tasks at the same time, making it possible to do more work with less hardware investment.

Figure 4-5 illustrates the Microsoft Hyper-V Manager after creating a VM running Ubuntu Linux.

Figure 4.5 Hyper-V Manager Running Ubuntu Linux

By running virtual machines on servers, fewer physical servers are required to perform the same tasks, which leads to continuing cost savings, easier scaling to suit the workload, and easier disaster recovery.

System images can be centrally created, modified, and managed for easier installation. Because the VMM acts as a translator between the VM and the actual computer hardware, fewer problems arise from differences in system hardware.

Resource Requirements

A workstation that will be used for virtualization needs to be designed with fast multicore processors and as much RAM as possible, given the limitations of the motherboard and VMM (or host operating system). For this reason, the preferred approach is to use 64-bit processors and a 64-bit-compatible VMM (and host operating system, if hosted virtualization is being used instead of a hypervisor). The 64-bit operating systems or VMMs are not subject to the 4GB RAM limit imposed by 32-bit architecture.

Processors selected for a virtualization system should also feature hardware-assisted virtualization. The system BIOS/UEFI firmware must support this feature and be enabled in the system BIOS/UEFI firmware. Otherwise, VMs will run much more slowly, and some VMMs will not be supported.

If several VMs will be run at the same time on a workstation, using two or more displays is highly recommended.

Although a VM is created using an actual operating system instead of a reproduction of one, the physical hardware that will be used for the VMM must meet or exceed the minimum requirements for the VMM. Consider some examples:

Note

SLAT (second-level address translation), also known as nested paging, reduces the overhead required to map virtual addresses to physical addresses. Reducing overhead makes it possible to run more virtual machines at the same time on a server.

Security Requirements

Virtual networks require the same attention to security details as physical networks. Because a single physical computer can house two or more VMs, knowing which computers in an organization are using VMs is a vital first step in securing a virtualized environment. The following are some issues to consider:

Exam Preparation Tasks

As mentioned in the Introduction, you have several choices for exam preparation: the exercises here; Chapter 10, “Final Preparation”; and the exam simulation questions in the Pearson Test Prep practice test software.

Review All the Key Topics

Review the most important topics in the chapter, noted with the Key Topic icon in the outer margin of the page. Table 4-2 lists these key topics and the page number on which each is found.

Table 4-2 Key Topics for Chapter 4

Key Topic Element

Description

Page Number

Section

Common Cloud Models

327

List

General types of cloud computing

329

Section

Shared Resources

330

Section

Desktop Virtualization

333

Section

Client-Side Virtualization Overview

334

Define Key Terms

Define the following key terms from this chapter, and check your answers in the glossary.

IaaS

SaaS

PaaS

public cloud computing

private cloud computing

hybrid cloud computing

community cloud computing

shared resources

metered utilization

rapid elasticity

high availability

file synchronization

on-demand

desktop virtualization

virtual desktop infrastructure (VDI)

sandboxing

test development

application virtualization

cross-platform virtualization

legacy software and operating systems

Answer Review Questions

  1. Match each of the following cloud-based models to its description.

    Model

    Description

    a. SaaS

    b. IaaS

    c. PaaS

    1. Provides access to storage, network services, virtualization, and servers

    2. Gives application developers the opportunity to develop and deploy software in a cloud environment

    3. Enables software to be hosted on remote servers and accessed through web browsers

  2. Which of the following are characteristics of a virtual machine? (Choose all that apply.)

    1. A user can access multiple guest operating systems without rebooting.

    2. 32-bit and 64-bit operating systems can be installed on different virtual machines on a single host machine.

    3. Multiple virtual machines use the same hardware as the host computer.

    4. Running multiple guest operating systems is more expensive than running those same operating systems as host systems.

  3. Which of the following are advantages of cloud computing? (Choose all that apply.)

    1. Rapid elasticity

    2. DHCP services

    3. Resource pooling

    4. Metered service

  4. What is the name of the program that acts as the translator between the host machine and its virtual machines?

    1. Virtual machine server

    2. Virtualization machine manager

    3. Virtual host manager

    4. Virtualized guest server

  5. The Windows 10 VM is selected in the following figure. Assuming that the host system has 8GB (8,192MB) of RAM, can you determine how much RAM will be available to the host system when the Windows 10 VM is running?

    1. 8192MB

    2. 2048MB

    3. 6144MB

    4. Impossible to determine from the image

  6. Which of the following best describes sandboxing as it relates to a virtual machine?

    1. It is a type of hybrid cloud computing.

    2. It is a type of firewall between the host server and the outside world.

    3. It is a backup for virtual machines.

    4. It is the isolation of VMs within the host system for better security.

  7. A VMM that runs directly on the hardware instead of inside the operating system is known as which of the following?

    1. Hypervisor

    2. Thin-client virtualization

    3. Client-side host/guest virtualization

    4. DEP (Data Execution Prevention)

  8. Which of the following refers to creating a user interface to a computer that is hosted on a central server on-premises or in the cloud?

    1. Community cloud

    2. File synchronization

    3. Desktop virtualization

    4. VM checkpoint

  9. The virtual software Microsoft 365 is running across platforms as well as operating systems, so users in the company on iPads, Linux devices, and macOS can have the same application software experience. What is this an example of?

    1. Virtual machine management

    2. Supporting legacy software and operating systems

    3. On-demand self-service

    4. Cross-platform virtualization

  10. A technician is setting up a workstation that will be used for virtualization. Which of the following should the technician ensure? (Choose three.)

    1. The system has as much RAM as possible.

    2. The BIOS/UEFI supports hardware-assisted virtualization.

    3. The VMM runs inside the guest operating system.

    4. Virtualization support must be enabled in the BIOS/UEFI.

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