[GLLUG] Virtualization Questions

Richard Houser rick at divinesymphony.net
Mon Oct 3 01:03:54 EDT 2011


> On KVM, from what I understand and I could be completely wrong, KVM is basically running each container off of the same kernel.

Completely wrong.  What you've described is closer to a BSD jail.  KVM
runs complete copies of the OS in question, although it requires
processor hardware support.  I'm running multiple Linux distros in
separate kernels, and even Windows (ick) for about a week at tax time
each year.  BTW, libvirtd is used to manage Xen, KVM, and qemu, so the
tooling is nearly identical.

On Sun, Oct 2, 2011 at 11:33 PM, Thomas Driscoll <tad001 at sunn.net> wrote:
> Currently, I am using Xen running on a Debian distribution. I used qemu on my workstation to make the first images (mistakes were made), and later images I just installed via an ISO. I am running my FreeBSD servers guests (of which most of my servers are) in HVM on the Debian/Xen host(s). So far I am very happy with it. I converted from VMwares Server version that was running on the original hardware. After switch to Xen, I was able to turn up an additional 3 machines on the same hardware. The setup/configuration of the networking was confusing and limited in documentation but once I figured out what they were doing it become very easy. I have 3 interface on the host and it each interface looks to a different network (LAN, WAN, and Mail (my back end for my mail systems)).
>
> On KVM, from what I understand and I could be completely wrong, KVM is basically running each container off of the same kernel. For me this was a problem as I am running FreeBSD, and that turned me to Xen. I can pass on my notes (which make sense to me but might not have the same effect for others) if you like. There are some good URLs I have collected for this topic. I plan to write up my experiences in the conversation to Xen, but life keeps getting in the way.
>
> I also use virtualbox on my workstation for running a WinXP box, and testing some live Linux CDs as needed, and some temporary system installs to test the stray odds and ends. Virtualbox has proved to be very helpful for man bits and pieces.
>
> As I mentioned qemu earlier, I have used that program for a long time and the networking pieces are very much like Xen (which can be confusing at the start). It used bridges and Tap interfaces to connect virtual machines to the network. It is because of this I usually have 2 interfaces on my workstation. That seems a lot of gibberish from me at this point. If anyone wants more information feel free to shoot me a request and I will pass on what I can.
>
> Tad
>
>
> On Sun, Oct 02, 2011 at 02:23:57PM -0400, Chick Tower wrote:
>> Since I may someday have a PC capable of running virtual PCs, I've been
>> wondering about it.  I know I could read up on virtualization on the
>> internet, but I thought I'd take the opportunity to boost traffic on our
>> little mailing list.
>>
>> Are there ready-made guest OS packages available, or do we have to
>> create our own?
>>
>> To create a guest OS package (or container or whatever the nomenclature
>> is), is it necessary to create an empty one and then install an OS, or
>> can you clone an existing OS installation?
>>
>> Is it possible to modify the saved version of a guest OS (such as for
>> software updates or configuration changes), or would you have to create
>> a new saved version?  I realize allowing the guest OS to permanently
>> modify itself could be considered a security risk (although
>> normally-installed OSes do it all the time), but it would be convenient.
>>
>> Can a running instance of a guest OS save data in external filesystems?
>>   If so, can those external filesystems be simply mounted like any
>> other, or would it require some trickery?
>>
>> I do not yet need to know the details of how to do the things I've asked
>> about.  I'm just curious as to how flexible virtualization is.
>> --
>>
>>                                 Chick
>> _______________________________________________
>> linux-user mailing list
>> linux-user at egr.msu.edu
>> http://mailman.egr.msu.edu/mailman/listinfo/linux-user
>
> --
>
> Thomas Driscoll
> e-mail: tad001 at sunn.net
> cell phone:(517)944.2041
>
>
> When they are fulfilled, be prepared against them; when they are strong, avoid them.
>
>         by: Sun Tzu
>
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