Virtualisation is the process of recreating a machine environment inside a machine. This machine are known as virtual machine.
- they are light weight (as they don't include a full OS)
- they permits to deploy software quickly.
A cloud environment is based completely on a virtual architecture.
To understand the mapping between physical and virtual concept, you should see the virtual layer page.
- Compartmentalization: you don't to pollute your normal working environment, and it's way easier to shut down/pause a VM if it starts to drag down your host system's peformance
- Ability to take snapshots and roll back a VM, which can be handy when testing patches or new configurations
- Ability to tweak resource allocation (memory, number of CPUs, etc) after the virtual server is created
- Allows creation of dynamically expanding disk images, so storage isn't allocated until it's needed. When you're looking at 250-300GB of storage for an EBS Vision install, that can be a big deal.
- Portability: If your VM is stored on an external drive, you can carry it with you for demos and whatnot. If you get pressed for space, you can burn the VM files to DVD and restore them later if needed.
Server virtualization and Storage
Server virtualization removes the virtual host dependencies from the physical hardware, making the server CPU and RAM resources elastic and variable. When a virtual host requires more server resources, they can be moved to another physical server.
Server virtualization techniques solve or alleviate server resource contention, but they do not resolve storage capacity or performance contention problems within the storage subsystem.
Server virtualization remains server-centric, and does not solve storage management issues, which remain outside the server virtualization management domain.