가상화(Virtualization)

Virtualization?

Use a single machines' hardware to run multiple virtual machines in it.

 

Key point:

• Use a system's Hardware.
• Allocate CPU/RAM/Storage to VMs.
• Cannot exceed the CPU/RAM/Storage that is available on physical hardware.

Benefits:

• Better use on H/W resources.
  • assume 2 physical servers that were running specific services for our network.
  • they may only be using less of CPU/RAM/Storage.
  • if we do virtualizatioin, we can put both of servers into one physical machine.
  • both server to run into one physical machine.
  • -> utilizing more of the CPU/RAM/Storage on that box.

• Flexibility : VMs can be moved between different data center.
• Recovery : VMs can be saved as files.
• Power Saving/Reduce footprint
  • we can consolidate multiple physical pieces of hardware into one smaller piece of hardware.
• Researching OS and other S/W (sandbox)
  • you can test things without having a physical unit.

*sandbox : secure, isolated environments used to test, ananyze or run code, applications or programs.

*footprint : the physical space a device takes up, or the amount of memory a program uses.

 

Hypervisor

Type 1 : Bare Metal Hypervisor

• installed directly on a bare metal server
• control hardware directly -> less overhead, can use hw resources more effectively
• administer VMs

ex)

VMWare vSphere/ESCi -> the hypervisor to use the VMs

Microsoft Hyper-V

Citrix XenServer

 

Type2 : Hosted Hypervisor

• installed on a host OS
• use hardware through Host OS -> have more overhead than Type 1 hypervisor
• use existing environment -> convenient to install  

ex)

Oracle Virtual Box

VMWare workstation / Fusion

Paralles (Mac)

 

 

VMs vs Containers

VMs build their own OS but Containers don't. They use the existing Host OS.

Virtual Machine

• HW level of virtualization (using hypervisor)
• Virtual Machine is working at the HW level.
• they create the separate work stations, separate servers out of one.
• there are Type1, Type2.
• with hypervisor, we can create different machines out of our server.
• we're interacting with what we're thinking is HW,
• but that's being managed for us by the hypervisor to what actually HW is.

Container

• OS level of virtualization (don't use hypervisor)
• Container is working at the OS level.
• we can run many dozens of containers in one instance of Host OS.
• It's kind of process isolation.
• Make sure that applications can only see what's absolutely necessary for them to run and nothing else.
• They shares the OS and Kernel, but it's appear to each container as if they have their own OS.
• only what's installed in them is the libraries that are needed, scripts, code, everything that we need to run our application.

 

ref:

https://youtu.be/L8A9PHeyRrY?si=n8tdpbN1XeL8Mry5

 

https://youtu.be/nvdnQX9UkMY?si=-S75LlQPu9OihdOk

 

https://youtu.be/wtumA3WqWs0?si=99_hYq1qNkaqdfaR

https://youtu.be/QMhFLv8kJUc?si=KP7eYFVnp8onuKRM