Installing Xen on a pc hard disk partition

posted in Hypervisor
Tuesday, May 06 2014, 04:18 PM
chess
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Hi everybody

I am a beginner at virtualization world and I am having my first steps with Xen.

My hard disk (1TB) is already partionned to 3 partitions :

C:/244GB supports windows

D:/235GB I use it for my personnal data

E:/440GB I use it for my personnal data

Since I want to install Xen with Debian, I am thinking about freeing the D:/ but I don't know if 250GB are suffient for Xen.

Second question is that debian require its own partioning as follows

sda1 - /boot 200MB

sda2 - / 15GB

sda3 - swap

sda4 - reserved for LVM

Does this make a conflict with an existing primary partitions?

Third question is if I install Xen, will Xen use the entire hardwre resources thus my windows partition will be considered as a guest machine or Xen is limited only to the hardware of the partition D:/


Thanks
Responses (8)
  • Accepted Answer

    Tuesday, May 06 2014, 06:06 PM - #permalink
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    Hi chess,

    From your questions, I am guessing that you want a dual-boot scenario. On boot-up, you want to choose to either boot your Windows environment or a Xen Project with Debian environment. Is that correct? Or are you expecting the current Windows instance to exist solely as a VM running on the hypervisor?

    If so, that should be easy enough to configure. To answer your first question, 250GB is more than enough space to work. The limitation is actually the size and number of the VMs you plan to use. That's where the real disk usage resides.

    In fact, the Xen Project software is quite small. Most of the basic installation will be Debian itself. The Xen Project kits (or source+binaries if you intend to compile it yourself; not really needed unless you want the latest and greatest) take megabytes, not gigabytes, to install.

    Regarding the partitioning: yes, there is a conflict. It is not insurmountable, but you will need to do some manual partitioning during install (do NOT use any option which wants to "use the entire disk"). BTW, the Debian installation manual can be found here:

    http://debian-handbook.info/browse/stable/sect.installation-steps.html

    I won't go down the details of repartitioning until we know for sure that you want to dual-boot.

    If you dual-boot, when the hypervisor is active, the partitions which contain Windows and your private data will be ignored, unless you explicitly access them. In a dual-boot, the machine will either be a Xen Project-based virtualization platform with a Debian control node (aka Dom0) and whatever VMs you choose to build, or the machine will be a standard Windows box; you choose during the boot-up of the box via a little menu of choices driven by grub.

    Does this give you a good starting point?

    We have a Beginner's Guide which might be useful:

    http://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide

    It lacks the details for manual partitioning, but it has quite a bit of useful information.

    Going forward, I'd suggest looking into using the xen-users mailing list. There are lots of people who hang out there and can help you with point-by-point assistance as you move forward in your installation. The Q&A forum currently has a much smaller following.

    To learn more about xen-users, look at:

    http://xenproject.org/help/mailing-list.html

    Note that you don't actually have to join the list (if you don't want to) in order to ask a question. However, monitoring the mailling list can be a very instructional activity in itself.

    Does this help?

    Russ
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  • Accepted Answer

    chess
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    Tuesday, May 06 2014, 08:55 PM - #permalink
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    Thank you Russell for your answer.

    Actually yes what you have guessed is correct. I want a dual-boot scenario. On boot-up, I want to choose to either boot Windows environment or a Xen Project with Debian environment.

    But unfortunately, I have not undersood very well.

    Could the partition of windows and the one of Xen work independentely?

    Or it is not possible since Xen is a type I hypervisor so Xen will consider windows as a guest machine.
    In other words, will Xen work only on the hard of the allocated partition or rather on the entire hard disk?

    Thank you again.
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  • Accepted Answer

    Wednesday, May 07 2014, 03:09 AM - #permalink
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    Hey chess,

    In a dual-boot scenario, you boot up either Xen Project+Debian or Windows. It's one or the other; they don't run simultaneously and they don't touch each other's disk space (unless you explicitly give permission).

    The Windows partition on the disk will not automatically be seen as a guest in a dual-boot situation. Of course, you could build one or more Windows VMs using some of the LVM storage, but they would be distinct from the original Windows instance.

    The rules for dual-boot with the hypervisor are the same as they are when you dual-boot Linux and Windows; no difference.

    Make sense?

    Russ
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  • Accepted Answer

    chess
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    Wednesday, May 07 2014, 04:18 AM - #permalink
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    Thank you very much Russell. It is very clear now.

    Could we please go back to the partioning and the eventual conflict.
    What I have understood is that I should start with an installation of debian in dual boot with windows without bothering about Xen for the moment.
    I should thus follow a tutorial for installing debian in dual boot with windows.

    Is there specific considerations for partitions?
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  • Accepted Answer

    Wednesday, May 07 2014, 04:10 PM - #permalink
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    Chess,

    When setting up for the dual-boot, the only real Xen Project-specific factor is the size of the LVM partition. You will be storing your VM images in there, so make sure it has plenty of room for whatever VMs you intend to create.

    Other than that, there is nothing in particular you need to do to set up the partitions; just set it up like a dual-boot Windows and Debian system, with an LVM partition available.

    Once you have Debian installed and the dual-boot with Windows working properly, then continue with a standard Xen Project hypervisor installation. That part of the installation should be the same as you'd do on any Debian system. Just be mindful to use the correct partition names according to the way you installed the system (e.g., on a non-dual-boot installation, the LVM partition might be called /dev/sda4, but on your machine the proper name might be /dev/sda7 because of the existance of all the Windows partitions). Those details will be evident during the installation, so just make notes to yourself as you do the install.

    Russ
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  • Accepted Answer

    chess
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    Wednesday, May 07 2014, 04:32 PM - #permalink
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    Thank you very much Russell for all these precious notices.
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  • Accepted Answer

    chess
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    Wednesday, May 07 2014, 06:13 PM - #permalink
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    Hi Russell;

    I would like to ask you if there is a problem if the partitions are logical?
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  • Accepted Answer

    Wednesday, May 07 2014, 06:28 PM - #permalink
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    If I remember correctly, only the /boot partition needs to be primary on the Debian+Xen side of things. I believe all the other Linux-related partitions can reside in an extended partition on the disk.

    As you are now at a state where you are moving along with the install, allow me to suggest that you begin taking questions to the xen-users mailing list. I certainly don't mind answering questions regarding details, but, frankly, I am a bit apprehensive that I might overlook something in my replies to you. One of the benefits of xen-users is that it has a wide selection of very experienced people who can correct information if someone forgets to mention some critical detail. We simply don't have as many people who follow this Q&A forum.

    To learn more about xen-users, look at:

    http://xenproject.org/help/mailing-list.html

    Remember that you don't actually have to join the list (if you don't want to) in order to ask a question.

    BTW, I will be lurking over there as well.

    Russ
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