LFS151.x Chapter 1

Question 1

What defines Cloud Computing? (NIST)

Answer 1

Cloud computing is a model for enabling
- ubiquitous,
- convenient,
- on-demand
network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be
rapidly provisioned
and released
with minimal management effort
or service provider interaction

+ Pay as you go Model

Question 2

What are common service categories?

Answer 2

• Infrastructure as a Service (IaaS)
• Platform as a Service (PaaS)
• Software as a Service (SaaS)

Question 3

Name a few additional service models?

Answer 3

• Analytics as a Service (AnaaS)
  - API as a Service (AaaS)
  - Big Data as a Service (BDaaS)
  - Business Process as a Service (BPaaS)
  - Code as a Service (CaaS)
  - Communications Platform as a Service (CPaaS)
  - Desktop as a Service (DaaS)
  - Database as a Service (DBaaS)
  - Function as a Service (FaaS)
  - Monitoring as a Service (MaaS)
  Anything as a Service (XaaS).

Question 4

What are key characteristics of Cloud computing? (7-8)

Answer 4

• Speed and Agility
• Cost
• Easy access to resources
• maintenance
• multitenancy
• realiability
• scalability and elasticity
• “security”

Question 5

Which deployment models are known?

Answer 5

• Private Cloud
• Public Cloud
• Hybrid Cloud
• PolyCloud
• Community Cloud
• Distributed Cloud

Question 6

What is virtualization?

Answer 6

Capability to create a virtual version of a physical compute resource, including a virtual computer hardware platform, operating system, virtual storage device, and virtual compute resource

Question 7

How can Virtualization be achivieved?

Answer 7

• Can be achivied at different software layers (Central Processing Unit, storage, memory, …)
  With several tools to create Virutal Machines (VM) by virtualizing essential hardware

Question 8

What is a VM?

Answer 8

• Software equivalent of a hardware-built computing machine, represents an isolated collection of virtual resources, behaving like an actual physical system

Question 9

How are VMs created?

Answer 9

With the help of a specialized virtualization software: hypervisor, that runs on the host machine

Question 10

What is a hypervisor?

Answer 10

• Software, capable of creating multiple isolated virtual operating environments
• Each isolated virtual operating environment is composed of virtualized resources that are then made available to the guest systems.

Question 11

What categories of hypervisors are classified?

Answer 11

Type-1 hypervisor (native or bare-metal)
Type-2 hypervisor (hosted)

Question 12

What is a Type-1 hypervisor?

Answer 12

• Runs directly on top of a physical host machines hardware without the need for host OS
• Typically found in enterprise settings
• Examples:
• AWS Nitro
• Red Hat Virtualization
• Microsoft Hyper-V

Question 13

What is a Type-2 hypervisor?

Answer 13

• Runs on top of the hosts OS
• Typically for end-users, may be found in enterprise settings?
  Examples:
• VirtualBox
• Vmware Player
• Vmware Workstation

Question 14

What are Exceptions to the dual hypervisor distinction?

Answer 14

• Linux Kernel modules that act as both type 1 and type-2 hypervisors at the same time
  Like:
• KVM
• Bhyve

Question 15

What do Hypervisors do?

Answer 15

• Enable virtualization of hardware such as CPU, disk, network
• Allow installation of guest VMs on top of them
  Multiple guest VMs can be created with different Operating Systems on a single Hypervisor

Question 16

What is hardware virtualization?

Answer 16

• The feature that allows hypervisors to virtualize physical hardware of a host system, thus sharing host systems processing resources with multiple guest systems in a safe and efficient manner
  Supported by most modern CPUs

Question 17

What is nested virtualization?

Answer 17

• Feature of a CPU to enable VMs to be created inside another VM

Question 18

What is KVM?

Answer 18

• Kernel-based Virtual Machine
• Open souce software that provides hardware-assisted virtualization to support various guest OSs
• Loadable virtualization module of the linux kernel
• Converts the kernel into a hypervisor capable of managing guest Virtual Machines
• Specific hardware virtualization extensions have to be available

Question 19

What Featues does KVM offer?

Answer 19

• Support various guest Oses, such as Linux Distributions, Windows, Solaris, etc
• Enables device abstraction of network interfaces, disk but not the processor
• Instead exposes the /dev/kvm interface that can be used by an external user space host for emulation
  ® Examples user space tools for KVM VM management: QEMU, virt-manager
• Supports nested virtualization
• Supports hotpluggable devices such as CPUs and PCI devices
• Supports Overcommitting
• By dynamically swaping resources from one guest that is not using the type of resource that is needed

Question 20

What is Overcommitting in the context of a hypervisor? Why is it possible?

Answer 20

• More virtualized CPUs and memory can be allocated to virtual machines than there are physical resources on the system
• Possible because most processes do not access 100% of their allocated resources all the time

Question 21

What are benefits of using a KVM?

Answer 21

• Open source solution, free to customize
• Zero costs
• Provides efficient hardare-assisted virtualizatoin for an array of guest Oses
• Provides para-virtualization of ethernet cards, disk I/O controllers, and graphical interfaces for guest Oses
• Highly scalable
• Employs advanced security features, utilizing SELinux
  Provides Mandatory Access Control security between Virtual Machine

Question 22

What are benefits of using VMs in a development environment?

Answer 22

• Reproducible environment
• Management of multiple projects, each in ist isolated and restricted environment
• Sharing the environment with other teammates
• Keepting the develpoment and deployment environments in sync
  Running consistently the same VM on different Oses leveraging hypervisors such as VirtualBox, Vmware, Hyper-V

Question 23

What is Vagrant and why is it good?

Answer 23

• Cross-plattform tool for building and maintaining portable virtual software development environments
• Provides great extensibility bauce various plugins can extend ist supports for custom providers, provisioners, commands and hosts

Question 24

What does Vagrant do?

Answer 24

• Helps automate VMs management by providing an end-to-end lifecycle management utility - the vagrant command line tool

Question 25

What are key components used by Vagrant to manage Virtual machines?

Answer 25

- Vagrantfile - Boxes - Providers - Synced Folders - Provisioning - Plugins - Networking - Multi-Machine

Question 26

How is the Vagrantfile used?

Answer 26

- Vagrant command reads the configuration give in the config file and does different operations

Question 27

What are Boxes in Vagrant?

Answer 27

- Package format for the Vagrant environment - Box images can be versioned and customized to specific needs simply by updating the Vagrantfile accordingly

Question 28

What are Providers in Vagrant?

Answer 28

- Underlying engines or hypervisors used to provision VMs or containers - Default is VirtualBox, also supports Hyper-V, Vmware, Docker - Custom providers may be configured

Question 29

How is Networking dealt with in Vagrant?

Answer 29

- High-level networking options are available for - Port forwarding - Network connectivity - Network creation - These network options represent an abstraction that enables cross-provider portability - The same file used to provision a VirtualBox VM could be used to provision a Vmware machine

Question 30

What is Multi-Machine in Vagrant?

Answer 30

- A projects Vagrantfile may describe multiple VMs, which are typically intended to work together or may be linked between themselves - For instance for accurately modeling a multi-server production topology, such as separating a web and a database server - Or modeling a distributed system

Question 31

What are benefits of using Vagrant?

Answer 31

- Automates the setup of one or more VMs, which results in saved time, increased productivity, lower operational costs - Introduces consistency in infrastructure provisioning through the Vagrantfile - Flexible cross-plattform tool - Provides support for Docker containers in addition to VMs provisioned Vmware, VirtualBox, Hyper-V - Easy to install and configure - Very useful in multi-developer teams