CHAPTER SEVEN: VIRTUALISATION & CLOUD CONCEPTS Flashcards
(36 cards)
What is Virtualization?
Virtualization is like making pretend computers inside your real computer.
You know how a computer normally runs one operating system (like Windows or macOS)? Well, virtualization lets you run many operating systems at once—all on the same machine.
It does this by adding a special layer of software that keeps everything separate and organized. That way, each virtual computer (called a virtual machine, or VM) thinks it has the whole machine to itself—even though it’s sharing.
What’s a Hypervisor?
The hypervisor is the “boss” software that creates and manages those pretend computers (the VMs).
Every operating system (like Windows, Linux, etc.) normally wants full control over your computer’s parts—like memory, CPU, and hard drive. The hypervisor steps in and says, “Hang on! I’ll share those resources fairly.”
Two kinds of hypervisors
Type 1 Hypervisor (Bare Metal)
- Installed directly on your computer’s hardware—no normal OS needed.
- It’s like turning your computer into a virtualization machine right from the start.
- Examples: VMware ESXi, Microsoft Hyper-V, Citrix XEN Server.
Type 2 Hypervisor (Host-Based)
- Installed inside your normal OS (like Windows or macOS).
- It’s just an app that runs like any other app, but it lets you run other OSs inside it.
- Examples: VMware Workstation, VirtualBox, Parallels.
Client-Side Virtualization
(On Your Own Computer)
This is when virtualization is used on regular computers like laptops or desktops.
Why use it?
Sandboxing: Test dangerous stuff like viruses without risking your real computer.
Legacy software: Run old programs that don’t work on your new OS.
Cross-platform testing: Try apps on different operating systems (like Windows AND Linux).
Training labs: Practice using software without breaking anything—when you’re done, just reset the VM.
Server-Side Virtualization
(On a Big Server)
This is for servers (computers that run websites, apps, or company systems).
Most servers don’t use all their power. Virtualization lets you run multiple servers on one machine, saving space, energy, and money.
For example, if one server uses only 10% of the computer’s power, you can run 9 more virtual servers on the same hardware. That’s called server consolidation.
Application Virtualization
This is when you don’t install apps directly on your computer. Instead, the app runs from a server and is either streamed to your device or run remotely.
- The app is always up to date.
- You don’t need to install it over and over on many machines.
examples: Citrix XenApp, Microsoft App-V, VMware ThinApp
Container Virtualization
This is like VMs but lighter and faster.
Instead of running full pretend computers, containers just isolate the apps within the same OS. So you’re not running multiple OSs, just multiple app environments.
Each app in a container thinks it’s running alone, but they’re actually sharing the same base operating system.
Key tool: Docker
Resource requirements for Virtualization Basics
To run virtualization properly, your computer needs to be powerful. You need to think about how much of everything (like memory and disk space) is required by:
- The hypervisor (the manager that controls the virtual machines).
- Each guest OS (the virtual computers you’re running).
Guest OS Security
Each virtual machine needs to be treated like a real computer when it comes to security:
- You still need to patch (update) the OS to protect it from bugs or hackers.
- You still need antivirus software, but running it on every VM can slow things down.
Solution: Some security tools can run on the host machine (the real computer) instead of every VM.
To make updating faster, many people patch a template image (a master copy of a VM), test it, then make clones of it to use.
rough VMs
A big risk is rogue VMs—virtual machines created without permission. These can be dangerous.
- When people create too many VMs without control, it causes VM sprawl.
- To fight this, companies use software to track and manage all VMs.
- another danger: bad developers could sneak in backdoors or logic bombs (hidden malicious code) inside VM templates. That’s why templates should only be made and stored in secure places.
Host Security
The host is the real computer where all the VMs live. If the host goes down (like it loses power), all the VMs crash too. So protecting the host is super important—it’s a single point of failure.
Hypervisor Security
The hypervisor also needs protection. One big threat is something called VM escaping, where malware on one VM tries to break out and mess with other VMs or the host computer.
Just like with other software, you need to keep the hypervisor updated with security patches.
CPU and Virtualization Extensions
Your computer’s CPU (brain) has special features to help virtualization run faster:
Intel calls theirs VT-x
AMD calls theirs AMD-V
SLAT (Second Level Address Translation)
Another important feature is SLAT (Second Level Address Translation)—it helps with memory performance when you’re running lots of VMs:
- Intel’s version is called EPT (Extended Page Tables)
- AMD’s version is RVI (Rapid Virtualization Indexing)
Not all CPUs have these features, and sometimes they’re turned off. You’ll need to check your CPU specs and your BIOS (system setup) to make sure they’re turned on.
Also, the more CPU power you have—like multiple cores or HyperThreading—the better your virtualization will perform.
System Memory (RAM)
Each virtual machine needs RAM, just like a real computer.
Example:
Windows 10 needs about 2 GB of RAM.
So if your host also needs 2 GB, you’ll need 4 GB total just to run one Windows VM.
More VMs = More RAM needed. If you’re just testing stuff, you might get away with using less.
Mass Storage
Each VM also takes up hard drive space.
The VM’s “hard drive” is actually a big file stored on the host.
Most hypervisors use a file that grows as needed.
A Windows VM might take up 20 GB or more.
If you want to use snapshots (save the state of a VM to go back to it later), you’ll need even more space.
Networking
Virtualization lets you create virtual networks, so all your VMs can talk to each other and to the outside world.
In big companies, they can even create virtual switches and routers using software.
Virtualization Security Requirements
With all these moving parts (host, VMs, hypervisor), security becomes even more important:
Watch out for rogue VMs.
Patch everything: VMs, host, and hypervisor.
Use trusted sources for VM templates.
Monitor for any unauthorized changes or additions.
And always keep security software and rules in place to detect threats early.
What is the Cloud?
The cloud is basically someone else’s computer that you rent over the Internet. Instead of owning and managing physical servers (like big computers that store and run your stuff), you can use the cloud to access things like websites, apps, or file storage whenever you need them. You only pay for what you use, like a utility bill. This is called pay-per-use billing.
Cloud Characteristics (a.k.a. what makes the cloud special)
- On-demand access
You can get resources like storage space, apps, or databases any time you want — just like streaming a movie whenever you want instead of buying DVDs. - You don’t manage the hardware
As a user, you don’t have to worry about the tech behind it all — you just use the services. That’s why it’s called a cloud — it hides the complicated stuff from you. - Metered Utilization
You only pay for what you use, just like a water or electricity bill. This usage is metered, which means it’s measured by things like:
- How much storage you use
- How much processing power you need
- How much data you send over the internet
- How many users are actively using the service
You can usually check a dashboard to see what you’re using and what you’re being charged for.
- Virtualization
This is a fancy way of saying the cloud provider pretends one big computer is many smaller ones, so each customer feels like they have their own. It’s like splitting one house into separate apartments. - High Availability (HA)
This means the cloud is designed to almost never go down. A common benchmark is “Five Nines” (99.999%), which means less than 6 minutes of downtime per year. - Scalability
If you need more power or storage, you can get it easily.
There are two types of scalabilities
Horizontal scaling (scaling out): Add more servers (like adding more checkout lanes in a store).
Vertical scaling (scaling up): Give one server more power (like upgrading a single cashier to be faster).
Types of Clouds (Deployment Models)
Types of Clouds (Deployment Models)
- Public Cloud (Multitenant)
- Private Cloud
- Community Cloud
- Hybrid Cloud
Public Cloud (Multitenant)
Offered by companies like Amazon (AWS), Microsoft (Azure), or Google (GCP)
Shared with other users — kind of like renting an apartment in a big building
You pay as you go or sometimes get free limited access
Good for general use, but you share the space, so performance and security risks can be higher
Multicloud: When a company uses multiple cloud providers at the same time
Private cloud
Owned and used by only one organization
More secure and controlled
Often used by banks, governments, or anyone dealing with sensitive data
Like owning a house instead of renting — more work, but more control
