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What is Virtualisation?

By VAR1016 ·
I was recommended to download VMWare, which I did. I subsequently uninstalled it because it doesn't tell me what it is - at least not in any way that I can recognise/understand. They keep sending me nice emails hoping I'm getting on with it (VM converter, virtual server etc.) and I thought I would try to find out something.

I looked up Wikipedia and got this page: http://en.wikipedia.org/wiki/Virtualisation. This tells me zero - just a lot of choices I do not recognise/understand except disk partitioning, which I do not understand but at least know how to use!

How can a computer be "virtual"? Either it's there or it isn't. Something has to work the numbers and store the stuff and so on.

Can anyone point me to a site that explains this in normal language?

Thanks

Paul

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re: There, but not there....

by ThumbsUp2 In reply to One question answered!

You said: "I cannot understand how something can be "there" but isn't!"

It really IS there. The primary OS ignores the fact that it's there because it's operating within the VM software environment, effectively being cloaked. The same happens when you're running within the VM environment. The virtual OS can't see outside of the VM environment. It doesn't know the primary OS is present.

So, you can think of the VM software as an envelope. What is outside of it can not see what is inside. What is inside can not see what is outside. Neither the outside or the inside are aware of each other. But, the VM software is aware of both.

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OK...

by VAR1016 In reply to re: There, but not there. ...

Thanks for that.

Now then the next question is "why?" Why would I want this, when I can partition my hard drive and run something else? I see I could run two operating systems sort of simultaneously, but I suppose this is for programmers/developers or some such. I was pointed to VMWare when I had problems trying to get remote desktop to work, but I don't see what this virtual business has to do with any of that.

Best wishes,
Paul

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I think the biggest use

by TonytheTiger In reply to OK...

is probably server consolidation (each virtual server replaces a real one) but it could be used as a terminal server... where each client gets a unique environment... and yes, it obviously would be useful as a test environment.

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Personally, I wouldn't........

by ThumbsUp2 In reply to OK...

If you remember correctly, you were trying to get two computers to run off of one monitor/keyboard/mouse and were having trouble understanding what a KVM switch (Keyboard/Video/Mouse) could do for you or how to install/use it. Since you were unable to get a KVM to work, someone had suggested you try Remote Desktop which wouldn't work because you didn't have room for a 2nd monitor/keyboard/mouse. It was at about that time someone suggested VMWare. Personally, I don't think this would solve your "space" problem because, without a KVM, it would still require a 2nd monitor/keyboard/mouse hooked to the 2nd computer so you could log into the "virtual" machine created on the first computer and control the 2nd computer from there.

So, you're mixing and matching parts and pieces of different problems trying to make sense out of it all and you're confused.

Go back to the KVM solution. Buy a KVM switch, hook both computers to it, boot each machine viewing them on one monitor as you log in, set up your network properly on both so you can see each machine from the other, THEN, either use remote desktop from the first computer to control the 2nd computer, or just share folders on the 2nd computer that you need access to their data.

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The Story So Far

by VAR1016 In reply to Personally, I wouldn't... ...

Thank you for persisting with this - and I am
very impressed that you remembered my earlier
problems.

Right now I have the two computers working
pretty well as I wanted them to.

Remote desktop works as does "my network
places" all via a cross-over cable.
Sometimes I have to log in on the second
computer before I can connect to it remotely,
and sometimes not! I have bought a cheap VGA
switch for use when either I have to log in
(spare keyboard stays on floor) or each week
when my IP address changes itself (that is
the IP address of the second computer). Then
I run CMD and ipconfig /all to get the
necessary information and after that Remote
log in remembers it - excellent.

I have to say I am very pleased with remote
desktop, so I have to offer another big thank
you to G-Man who came up with the solution to
make it work.

I would genuinely like to understand VMWare
etc. but frankly I think it's beyond me at
present!
Thanks and best wishes

Paul

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Well Paul maybe this will help you understand

by OH Smeg In reply to What is Virtualisation?

When you run a OS inside a OS virtually it removes a lot of issues that you would otherwise need to address. As the Virtual OS has no direct contact with the hardware it only sort of works with the running OS which to the Virtual OS is the hardware. The Virtual OS is Isolated from the Hardware and has no direct contact and doesn't need direct access to it's own individual HDD partition or space in RAM.

It effectively tot he Hardware and everything around it becomes nothing more than a running application within a program in this case VM Ware. The actual Partition Created isn't Real it only exists within the confines of the Software that it runs on. A Real OS has direct control over the Hardware that it runs on but a Virtual OS doesn't have this control as it never actually has direct contact with the Hardware what it thinks is the hardware is nothing more than code running within a Application that fools the OS into thinking that it is actually controlling something. The role of a OS is to provide an Environment to allow some for of work to be done be that play games run a Giant Data Base or whatever the OS allows the application to run but in the case of a Virtual Environment the OS doesn't even do this all it actually controls is nothing it's only interfacing with some cleaver programing that it thinks is Hardware.

So maybe thinking of things this way is that a Virtual Environment is a way to Fool a Operating System into thinking that it's actually controlling something when it's not. In the case of a Dual Boot Option all the Installed OS's are actually controlling the Hardware when they are running when not in use they are shut down and not running but in a Virtual Environment all Installed OS that are started are running all of the time.

I hope that is of some assistance to help you understand. And yes I know it's as Clear as Mud.

Col

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As you say...

by VAR1016 In reply to Well Paul maybe this will ...

Clear as mud! :)

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Well maybe this will help

by OH Smeg In reply to As you say...

A Virtual OS is one that runs inside another and has not direct connection or control of the Hardware.

It runs in a Virtual World and only thinks that it is controlling anything.


This allows Software than normally could not be run to be used on Incompatible Hardware because there is no direct connection between the OS, Software and Hardware only the OS and Software work together but the entire process allows things that normally can not work to work.

Or another way of looking at it is that it allows a Dangerous thing to be done which could result in the destruction of the OS itself to be done without any risk of stopping the real computer running. It allows things to be done that normally can not or are too dangerous to do to be done safely.

Sorry but I don't know how to make it any simpler than that.

Col

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To best understand it, forget the word Virtualisation ...

by OldER Mycroft In reply to What is Virtualisation?

Think of the situation in terms of Emulation.

That is at least a word that can be thought of in terms of REAL LIFE. If you were to see someone doing something that you thought was impressive or looked like being fun - you could attempt to 'emulate' their approach to the thing they were doing.

In computing terms, emulators abound (if you are interested in them and bother looking for them).

If you were to travel back in time, almost 30 years ago, computers were in their infancy as far as the domestic variety were concerned. The first domestic computers available to the average punter were things like the beasties that came out of the Sinclair factory in the UK, and the Commodore output from America.

If you were to try and play with, let alone find, a Sinclair Spectrum 48K or a Commodore 64, you might have your work cut out. You can however, run Spectrum and C64 emulators on a modern PC. Once the emulator is running, you can then load the Spectrum or C64 program into the emulator and play the game.

In terms of compatibility, you cannot run a Spectrum 48K program or a Commodore 64 program on a PC, but the emulator will allow it. So the emulator fools the program into thinking it is actually running on a Spectrum 48K or a Commodore 64.

If you were to push the program too far, or interfere with its code (using Peeks & Pokes) you would obviously damage the program, but ONLY inside the emulator - because the PC is kidding on that it is another machine.

The enxt time you start the Speccy or C64 emulator, everything is back to normal because strictly speaking neither of them actually exist - they are VIRTUAL.

The same goes for running older versions of PCs. Instead of hunting far and wide for a PC equipped with an 80286 processor so that you can fire up MS-DOS 4.2, then run a DOS program on it - you simply run VMM and create a virtual 80286-machine, complete with MS-DOS 4.2 mounted on its own virtual hard drive.

If anything goes wrong, even if you get online with it and get a virus infection, it doesn't matter - because the 80286 PC doesn't actually exist - it is also virtual, just like the Speccy or the C64.

'Virtual' is more a buzzword (and a hindrance when trying to understand it) - 'Emulator' is far easier to understand and basically exactly the same thing. :)

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Good stuff

by VAR1016 In reply to To best understand it, fo ...

Thanks OM. The concept of emulation does
help a little.

Tell me, suppose for example I wanted to run
XP Home inside my XP Pro set up -
"virtually". Would I have to install the OS
as I would with a clean computer, or have I
again missed the point?

Paul

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