John Howard - Senior Program Manager in the Hyper-V team at Microsoft

Senior Program Manager, Hyper-V team, Windows Core Operating System Division.

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Turning off differencing disks, and a Virtualisation Live and Uncut rerun anyone?

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Thanks to everyone who attended the "Virtualisation Live & Uncut" TechNet evening at the Microsoft office in Reading last night - I had a fantastic time, and it was great to have such an interactive audience. I think I now understand a lot more about your concerns and areas to focus on. The unscheduled follow-on "unplugged" bit was great - if I repeat the event, I'll bring a guitar with me. So, in that vain, if you missed yesterdays event but would like a rerun, please add a comment to this entry - if there's enough interest (maybe in Birmingham/Manchester?), I have the means to get it organised.

So, back to a question asked of me, and also one which I've asked myself but never given an answer serious consideration. Suppose you use differencing disks to build say 20 virtual machines all from a single base image. You run them for months for testing purposes, but discover that the size of the differencing disk is growing huge - to the extent that you would have been better off (in terms of physical disk utilisation) using dynamically expanding or perhaps even fixed disks. One downside of a differencing disk is that there is no means to compact them as you can for a dynamically expanding disk - it just grows and grows.

A solution, although not perhaps the most trivial to implement, is to use VSMT to perform a V2V (Virtual to Virtual) migration, deploying the image back to a dynamically expanding or fixed disk. Not ideal, but exactly something I'll be doing this weekend (but only 5 machines in my case).

Comments
  • A great evening John, I learnt a lot, many thanks. I use virtualisation on the desktop, but virtualisation on the server is sure an exciting area I'll now be pursuing.

  • Hi John

    Firstly I must thankyou for a very interesting evening, it has resolved a problem I had to solve for a client. But there is a question that did not come to mind on the evening. That is if you have a pc running XP and then you have virtual pc running on that same pc again running xp do you require a second lic or do you us the same lic from that pc.

  • Hi John

    Glad you enjoyed the evening! In the situation you have described you must have a licence for each instance of XP, whether that be virtual or physical. In other words, you need two licences.

  • Morning John

    There are 5 peaple on this network that would require this service, if I used Virtual server would that still be the case.

    john

  • Hi John

    Can you drop me a mail through the "contact" option at the top left of this page with a few more details?

    Thanks,
    John.

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