FAQ: Virtualization - What is it?

Discussion in 'Virtualized Computing' started by sabregen, Nov 19, 2008.

  1. sabregen

    sabregen Permabanned

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    For those of you new to virtualization, or just new to this subforum (I guess that includes everyone, since it’s brand new), I’m going to ask for suggestions on what to include on this FAQ, but I’ll kick in some of my own information, as I am recently a VMWare whore, having just achieved VCP certification, myself. To start off, for those that are utterly new to all of this, I’ll give some background information on what virtualization is, and why you’ll be interested. However, as the majority of my knowledge is confined to VMWare solutions, I will stick to that. Anyone more familiar with Xen, Virtual PC, Virtual Server, and Windows 2008 Hyper-V should chime in with their information.

     
    Last edited: Jan 29, 2010
  2. sabregen

    sabregen Permabanned

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    What does it look like on my desktop?

    It looks like this! This is an XP 32bit VM that I have running in VMWare Workstation on my laptop. I am running this VM because my host OS is Vista Ultimate x64, and I need to be able to use the Cisco VPN software for when I am doing admin work from home, or somewhere that's not the main office. Unfortunately, Cisco apparently has no plans to make an x64 VPN client, so I have to run a VM. I fire up my laptop, fire up VMWare Wrokstation, power on the the XP VM, and then launch the Cisco VPN software. Once I'm connected through the VPN in the VM, I can do anything in that VM as if I was at work, running XP. The side effect of running the VPN inside of a VM is a nice one...usually when you VPN into another network, all of your traffic all of a sudden is going through that VPN connection. This is still the case when you run VPN inside of a VM, but now the only traffic that's going over the VPN is the traffic inside the VM. The host OS is still maintaining the same connection that it's always had. I can run a VM and be on the VPN, and still get to my other machines on my home network, because the only traffic that's tunneling is the traffic from the VM, if that makes sense. Here's a screenshot:

    [​IMG]
     
  3. number69

    number69 [H]ard|Gawd

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    Nice post. Another good reason for virtualization is testing an OS, any software that will run on it..etc.. which should be pretty obvious.
     
  4. SockMan!

    SockMan! 2[H]4U

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    Also note that when people speak of Virutalization in general, they are usually talking about OS virtualization (such as running Windows in a VMWare virtual machine). However, Virturalization can happen at many different levels other than an entire machine - such as a virtual hard drive over a SAN.
     
  5. sabregen

    sabregen Permabanned

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    number69 - thanks. I'll need to update it as my brain clears, and as I get more feedback. You're right though, virtual machines do definately assist in dev & test environment work for a growing number of people and companies. Just last night I built a Vista 32bit test VM, to make sure that I understoof how to properly link a MyMovies client to my configured database, and make sure that I had all of the UNC paths correct. No drivers to install (just VMWare Tools), and didn't even bother updating with Microsoft, just installed and tested. Now I have a good baseline for rebuilding my HTPC, and I know exactly what I have to do.

    SockMan! - no doubt you are 100% correct. However, the thread will hopefully serve as a jumpoff, and perhaps we can cover sotrage virtualization here in a little bit. I suppose I should add that to the list?
     
  6. rgratto2

    rgratto2 2[H]4U

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    I feel as though you need a more concise sentence or two in your opening paragraph about virtualization that details its main usage - its ability to virtualize the hardware to allow for multiple operating system installations to run simultaneously on a physical machine.

    I was reading through it and kept waiting for that sentence where a reader who was learning about it for the first time would be like "oh, so that's why I would do this..." I feel like you were getting too far into the details without giving a definitive summary of the topic.
     
  7. pfunkman

    pfunkman 2[H]4U

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  8. sabregen

    sabregen Permabanned

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    I'll +1 this myself. I think you've hit the nail on the head. Thanks.
     
  9. Hurin

    Hurin 2[H]4U

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    In the "a picture is worth a thousand words" mode of thinking here. . . some type of screenshot with a windows desktop running a few virtualized OSes in windows would probably work wonders in making that light-bulb pop on over people's heads. :D
     
  10. sabregen

    sabregen Permabanned

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    Indeed, you are likely correct, and I was actually just thinking that while I was adding content. I'll get cracking...since I just decided that I wanted to use Vista on my streaming machine instead of XP...I'll have a go from the beginning. :p
     
  11. Gorankar

    Gorankar [H]ardForum Junkie

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    deleted by gorankar
     
  12. nitrobass24

    nitrobass24 [H]ard|DCer of the Month - December 2009

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    Sabregen I think its time for some more tutorials

    I was thinking about making a Windows Hyper-V Server tutorial(just started playing with it but it seems pretty cool).
    Maybe you could do an ESX tutorial(since that is your expertise)
     
  13. The_Mage18

    The_Mage18 [H]ard|Gawd

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    I think you should include a small section regarding para-virtualization and what the difference is between para and full. Also, you're incorrect regarding Windows and virtualization. Windows server 2008 is fully virtualization aware. Windows server 2003 and Windows XP can be partially para-virtualized using Novell's Virtualization Driver Pack and their implementation of XEN Virtual Server.
     
  14. sabregen

    sabregen Permabanned

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    I probably could, now that you mention it, since I've managed to virtualize it, it would be trivial.
     
  15. sabregen

    sabregen Permabanned

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    You're right, adding information between paravirtualization and fully virtualized environments would be useful. I'll have to add that to the list of ideas to cover. Thanks.

    Well, you're correct regarding the additions available for Windows 2003 and XP from Novell under Xen, however, the statement that I made is also true. The operating systems themselves are completely unaware of what's going on. They require the addition of non-Microsoft software in a specific Xen environment to achieve that level of functionality.

    Also, Server 2008, itself, runs in a Hypervisor. Technically, it is aware of virtualization takign place, however, since it itself is virtualized, that sort of creates a conundrum to try and explain, and is beyond the scope of a newcomer's understanding (IMO, and I am making assumptions, admittedly).
     
  16. The_Mage18

    The_Mage18 [H]ard|Gawd

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    Awwwww come on! I want to watch the glazed over look in their eyes and hear the POP when their brain snaps!! :D

    I agree though, that would be a bit much to try and explain. Minus the para-virtual part, ignore the rest of my previous post. ;)
     
  17. sabregen

    sabregen Permabanned

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    ...you should have seen my face the first time I tried to comprehend how virtual center could be a vm running on a physical host...that it was managing. I just about caved.

    EDIT: This post made [H]ardness Supreme official. SWEET:eek:
     
  18. sabregen

    sabregen Permabanned

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    updated the pics and info on running a VM in a hosted environment. I'll add full virt vs para virt info here in a bit
     
  19. sabregen

    sabregen Permabanned

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    added full versus para information to post #2
     
  20. mightydarv

    mightydarv n00bie

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    Just wanted to drop a quick thank-you note in here, as I have the sneaking suspicion I'll be hanging out in here lurking a good deal. I do a lot with virtuals at work, and having a forum here where I can pick the brains of people far smarter will be a very nice thing. Also, I'm looking forward to picking up some VMWare info as I have almost exclusively used Microsoft solutions up until now, and we are talking about expanding into VMWare support.
     
  21. rgratto2

    rgratto2 2[H]4U

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    Oh wow its come a long way in a short time, good work!
     
  22. sabregen

    sabregen Permabanned

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    thanks. I try to keep myself busy :)
     
  23. unhappy_mage

    unhappy_mage [H]ard|DCer of the Month - October 2005

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    Not true. I've run a 64-bit Linux guest on 64-bit hardware with a 32-bit Linux on it. See VMware's FAQ on this.
     
  24. sabregen

    sabregen Permabanned

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    so you are saying that your configuration was as such:

    Linux 32bit Host OS running VMWare Server
    Guest OS running Linux x64

    I followed the link, and read the whole thing, but I could not find the specific example that seemed relevant to how this is achieved. I could have just missed it. The second question I have is...why?
     
  25. pfunkman

    pfunkman 2[H]4U

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    Your link contains absolutely nothing to support what your saying. In fact it has nothing to do with Host OS requirements.

    I would really be interested in how you did it though.
     
  26. SockMan!

    SockMan! 2[H]4U

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    You may want to briefly discuss emulation: what it is, how it's different from virtualization, why you can't virtualize a PlayStation on your PC, etc.

    Also, you should add a definition for "hypervisor".
     
  27. sabregen

    sabregen Permabanned

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    good suggestions. Thanks, I'll get on it.

    Although, You can emulate a Playstation on PC, you're right in saying that you can't virtualize one.
     
  28. unhappy_mage

    unhappy_mage [H]ard|DCer of the Month - October 2005

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    Exactly.
    Well, as long as the hardware requirements are met, the software works fine. As for why: Some devices have only 32-bit drivers, so you can run a 32-bit OS on the hardware and still use 64-bit guests. 64-bit guests are useful for testing platforms; if you need to check if your software works on 64-bit machines you can do so.
    The host OS doesn't factor into it. VMware switches the processor in and out of 64-bit mode.

    Here's a link to the VMware forums. They don't say much about the subject other than "it works"... because it just works.
     
  29. sabregen

    sabregen Permabanned

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    and how's the performance on that type of implementation? I would expect to see a performance hit for doing the mode switching on two actively running OS's.

    Also, does this only apply to VMWare Server, or does it also apply to their other hosted solutions, like Workstation for Windows, Linux and VMWare Fusion?
     
  30. sabregen

    sabregen Permabanned

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    update. I pegged the 20,000 character per post limit in post #1, and am having to move some stuff to post #2 to accomodate the requests. I wonder if I can get a post or two inserted!? I'll have to ask.
     
  31. unhappy_mage

    unhappy_mage [H]ard|DCer of the Month - October 2005

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    I haven't done any performance tests, so take it with a grain of salt... but you're already doing sort of a super context switch to do 32-on-32 virtualization. I wouldn't expect 64-bit to be much more expensive than that, but I don't know what is entailed in switching from 32 to 64 bit mode.
    As far as I know. VMware Workstation and Fusion explicitly mention 64-bit support on their respective pages.
     
  32. sabregen

    sabregen Permabanned

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    Yes, I know that you can both support 64bit OS's, but my specific question was whether you knew if they supported 64bit OS's on 32bit hosts, as you have stated that Server does.
     
  33. Vader

    Vader [H]ardness Supreme

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    Ahh...I see the dreaded Cisco VPN client forced an XP VM...lol....i'm in the same boat...
     
  34. MrMike

    MrMike [H]ardness Supreme

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    As soon as I saw this I thought, "Now we just need a screenshot of one with the Nortel client in it also."

    Wtf is wrong with these companies? lol.
     
  35. sabregen

    sabregen Permabanned

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    Well, in my case I can;t use the web SSL client on our ASA to achieve what I need when I am away from the office, so I have to run the damned client...and Cisco can kiss my grits for not having a 64bit client.
     
  36. QHalo

    QHalo 2[H]4U

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    F'in A about the 64bit client.
     
  37. Dan_D

    Dan_D [H]ardOCP Motherboard Editor

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    I use this quite a bit at home on my Skulltrail setup.
     
  38. sabregen

    sabregen Permabanned

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    You use use the Cisco client or VMs?
     
  39. kencheeto

    kencheeto 2[H]4U

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    FYI small syntax mistake in the first sentence, second paragraph after you list your specs- 'less with more' should be 'more with less' .. I think.

    Just thought you should fix it- I don't know a thing about virtualization, overall a decent introduction. Might want to include some examples of why normal home users would use VMs, such as various [H] users who don't already use VMs at work.
     
  40. Gott

    Gott [H]ardness Supreme

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    When I need to VPN into work on my home machine, I fire up my XP VM to make the connection.