Virtualization
Virtualization and distributed systems¶
Why distributed systems need virtualization?
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portability is greatly improved as virtual machines provide a further decoupling between hardware and software, allowing a complete environment to be moved from one machine to another.
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Imporatnt in the context of reliability and security for (distributed) systems as it allows for the isolation of a complete application and its environment, a failure caused by an error or security attack need no longer affect a complete machine.
Types of virtualization¶
Three different types of virtualization
| Type | Characteristic | Advantage | |
|---|---|---|---|
| A process virtual machine | Virtualization is only for a single process |  |
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| A native virtual machine monitor | Interface offered by a virtual machine monitor can be offered simultaneously to different programs | Different guest operating systems can run independently and concurrently on the same platform. |  |
| A hosted virtual machine monitor | Make use of existing facilities provided by that host operating system | Easy to implement |  |
Application of virtual machines to distributed systems¶
Three different types service provided by cloud
| Service | Characteristic |
|---|---|
| Infrastructure-as-a-Service (IaaS) | covering the basic infrastructure |
| Platform-as-a-Service (PaaS) | covering system-level services |
| Software-as-a-Service (SaaS) | containing actual applications |
Virtualization plays a key role in IaaS. Instead of renting out a physical machine, a cloud provider will rent out a virtual machine (monitor) that may, or may not, be sharing a physical machine with other customers.
最后更新:
2021-12-23 11:28:58
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