I dont know what is virtualization
1.please explain in simple terms
2.for linux admin how it helps in carrer
3.is their any tools for this
4. RHCVA is belongs to this or not

thanks in advance

You can look it up...there are plenty of online resources:
http://en.wikipedia.org/wiki/Virtualization
It doesn't, unless your company uses Linux virtualization.
Lots, from KVM to virtualbox, to VMware. Again, you can look them up easily.
The course guidelines and requirements can be found on Red Hat's training website.
http://www.redhat.com/training/

to put what virtualization is in simple terms one has to take a step back and think about how software runs on computers in the first place.
there are two main ways of running software on a computer, the 'bare metal' approach and with an operating system

the 'bare metal' approach used to be how all software was run on computers, and is still relevant for specialized tasks such as embedded devices like remote controls and microwave ovens, the upside to this is it has less overhead than with on operating system, the downside is that only one program can be run at a time and any 'drivers' have to be built into the system,

enter the operating system, which adds a layer of abstraction between the hardware and software and adds process management so more than one program can be run at a time, and software doesn't have to be specialized to the specific hardware, just the operating system and it's libraries.

virtualizaion adds yet another layer, known as a hypervisor and/or a virtual machine which is a software program that can either run 'bare metal' or on top of a 'host' operating system, the virtual machine then pretends to be a computer on which you can install a full operating system, allowing you to create more than one virtual machine, and thus allow you to run more than one simultaneous operating system. a cloud allows you to make multiple real machines act as one or more virtual machines, but the point is that the resources of those virtual machines is shared across all the real machines.


as mentioned by the previous poster, it depends on the work environment, but knowledge of virtualization can get you into jobs that require such knowledge.
certainly, there's the list provided above, as well as xen, and a few others such as qemu and bochs which are actually emulators as well as virtual machines.
note virtual machines run on the host hardware, emulators actually can pretend to be a different architecture altogether.

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