GEEP session on Virtualization
GEEP — GEEKs Of Pune…
GEEP is a non-profit group to promote Linux system software.You can find more details at :-
On 25th May’08 GEEP has organized the session on Virtualization.There were two presentations:-
a. For beginners by me.
b. For advance users by Mr. Amit Shah
If we put “vitualization” on any search engine we get ‘n’ number of results and get confused.
So, I put more emphasis on the basics.
I started my talk by comparing abstraction and virtualizarion.In virtualization we do not hide the underlying details and real system is transformed so that it appears to be different. For abstraction you can think of the OSI model.
Then I talked about the “Why Virtualization”. Some of the reasons are:-
* Server consolidation *Multiple execution environments
* Virtual hardware * Debugging
* Software migration (Mobility) * Testing/Quality Assurance
* Live Migration * Balancing Resources
If we talk about virtualization then we definitely has to talk about the computer architecture.
* ISA (Instruction set architecture ) divides hardware and software. There are two kind of ISA, User ISA and System ISA.
* ABI (Application Binary Interface) provides a program with access to the hardware resource and services available in a system. It consists of User ISA and System Call Interfaces
* API (Application Programming Interface) is a source code interface that an operating system, library or service provides to support requests made by computer programs.
clib in Unix environment : supports the UNIX/C programming .
By taking above things in mind we can divide Virtual Machines in two categories:-
Process VM at the ABI level: Virtualization of individual processes.
E.g., running x86 applications on Alpha CPU.
Java is another example of process virtualizaton. When we compile a java program, it is compiled into some kind a pseudo language which can interpreted by a jvm(java virtual machine). That is java is platform independent. Please note that jvm is different is each platform.
Process virtualization is a matter of correct functioning and not a matter of performance.
System VM at the ISA level.
Virtualization of complete systems
E.g., running Linux (and its applications) on Windows.
In system virtualiztion I talked about hardware emulation, hypervisor, full and para virtualization.I referred following for the same.
Then I talked about a bit kvm and handed over to Amit.
Amit’s presentation was awesome.
I was surprised to know that kvm is now supporting para-virtualization as well.