Chapter 22: Virtualization (A+ Study Notes)

A+

Study Notebook

---

You can find my complete study notes in Google Docs format below: https://docs.google.com/document/d/1zcKLWfsns1tqzmXtVRJbcd9NqfaEcjifgIo-oJIbEgc/edit?usp=sharing

References:
M. MEYERS, 2019.  CompTIA A+ All-in-One Exam Guide. 10th ed.

---

Chapter 22: Virtualization

• Virtualization benefits:
• Power saving
• Hardware consolidation
• System management and security
• Research

• Hypervisor - host which runs the Virtual Machine 
• Type 1 - Installs VM on Hardware like OS (bare metal/ native) 
• Microsoft Hyper-V
• VMware ESX/ESXi
• Oracle VM server
• KVM
• Citrix XenServer
  
  Mostly used `headless` to run multiple Servers at the same time. Has good access to all hardware. As such saves energy, power, resources, etc. Also provides each VM with its own individual IP address.
  
  Most server farms (data centers) providing Cloud services (Website hosting, server in the cloud etc.) run on Virtual Machines.
  
  
• Type 2  - These types are run as a software on the already installed OS 
• FreeBSD
• Vintage Hypervisor
• VirtualBox
• Vmware Workstation

Good for testing a remote connection to the server, or simply test a new OS etc. 

• Virtualization - divides hardware portion of the host system into individual virtual machines
• Emulation -  converts hardware/ software into entirely different platform 
• E.g. old nintendo emulator etc.
  

• Network types in VM:
• Bridged (uses same network card as the Host machine) 
• NAT (creates a Virtual Router, as such it receives its own network ID)

In Virtual Machine global settings you get create multiple Networks with various IP address configurations, and then assign this network settings to the individual Virtual Machines. 

• Internal Network (its own internal Network without access to the Internet) 
• Host-only Adapter (Uses only Hosts OS for network operations) 
• Generic (allows it to pretend to be another network card, e.g. if you use very old Machine, it can emulate the older network card
  

• Cloud
• Virtualization - cloud relies on it. Enables savings of power, resources, recovery, security. 
• Shared Resources - hardware can be virtualized, combined and then shared
• Rapid elasticity (scalability/adaptability/switching demand on resources when and as needed e.g. increase storage, decrease etc. Without any manual labour involved (removing massive HDDs, servers etc.). All can be done with a few clicks of a button.)
• On-damand (In other words “Seasonal”, for e.g. if there is a football match going on and we know that website will require a lot of resources to deal with the demand. As such it can be tuned up, to accommodate that, and then ass soon as the event is finished tune it down)
• Resource pooling (providers resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand) 
• Multi-tenancy - sharing of software between tenants 
• Data partitioning - e.g. keeping data from different tenants in different locations to reduce latency.
• Measured and Metered Services
  
• 3 Cloud Delivery Methods:
• IaaS (Infrastructure as a Service) - Compute, Network, Storage. Install virtual PC in the cloud e.g. specify OS, ram, storage, network controllers, firewall etc. 
• Vendor provides:
• Servers and storage
• Networking resources
• Data center
• Managed by user:
• Hosted apps
• Development and management tools
• Operating System (OS)
• In other words: you can use e.g. Amazon's AWS heavy hardware/already established Infrastructure as a Service. And if we need power or unlimited storage, we can simply get more VMs/  Servers. 
• DigitalOcean, Linode, Rackspace, AWS, Cisco Metapod, Microsoft Azure, Google Compute Engine (GCE)
• Perfect for: IT Administrators
  
• PaaS (Platform as a Service) - gives programmers tools needed to deploy, administer and maintain a Web application. Without the need to worry about operating system, software updates, storage, infrastructure. Because there is no physical hardware involved, and everrything is in the cloud - it becomes extremely easy to collaborate with various teams from all across the world. As a result, reducing the cost, and developing bigger, better, faster apps. 
• PaaS vendor provide a framework upon which developers can build upon. Development tools, middleware, Operating System (OS), database management system. 
• Vendor Provides:
• Development and management tools
• Operating System (OS)
• Servers and storage
• Networking resources
• Data center
• Managed by user:
• Hosted applications
• AWS Elastic Beanstalk, Windows Azure, Heroku, Force.com, Google App Engine, Apache Stratos, OpenShift
• Perfect for: Software Engineers, software developers
  
• SaaS (Software as a Service) - allows people to use cloud-based web applications. Software and hardware are provided and managed by a vendor, so consumer doesn’t  need to install or configure anything.
• Office 365, Google Apps, Dropbox, Salesforce, Cisco WebEx, Concur, GoToMeeting
• Vendor provides: 
• Hosted applications
• Development and management tools
• Operating System (OS)
• Servers and storage
• Networking resources
• Data Center
• Managed by user:
• None
• Perfect for: end users

• Deployment models: 
• Public Cloud - owned and operated by companies that offer rapid access over a public network to affordable computing resources. 
• Hardware, software, infrastructure all owned and managed by providers. 
• Low level of security. 
• Private Cloud - infrastructure owned by a single institution, organization or enterprise. 
• Hosted internally or externally. 
• More control over resources and multi-tenancy 
• High security
• Hybrid Cloud - uses both private and public loud. 
• Most companies use a mixture of private cloud and public cloud. 
• Allows companies to abuse best of both clouds:
• Use Private Cloud for Critical and Sensitive Data, and use public cloud for resources like SaaS for the latest applications and IaaS for elastic virtual resources.
• Portability of data, apps and services
• Multicloud - Ability to connect one or more public, private or hybrid clouds to on-premise systems and can network one or more clouds to other clouds.