[HCoop-Discuss] Our ideal architecture?

[David Snider]

KVM versus Xen:
http://searchservervirtualization.techtarget.com/news/article/0,289142,sid94_gci1318772,00.html

http://blogs.zdnet.com/virtualization/?p=415

http://wiki.xensource.com/xenwiki/Open_Topics_For_Discussion?action=AttachFile&do=get&target=Quantitative+Comparison+of+Xen+and+KVM.pdf


So, KVM is a part of linux. It uses Linux memory management and scheduling
which has the advantage of being able to quickly swap guests in and out
without rebooting. You can also see guest OS's as regular processes in the
host OS and use top,kill, etc to manage them. Of course, this means that it
has weaker isolation.

Xen is an independent layer from the host operating system. It acts as a
true hypervisor. Guest processes scale linearly with the number of guest
OS's. According the the 3rd link KVM guests start crashing after 4 guests. 

If I had to make a decision right now I'd go with Xen.

On Mon, 01 Jun 2009 19:08:18 -0400, Adam Chlipala <adamc at hcoop.net> wrote:
> Davor Ocelic wrote:
>> On Sun, 31 May 2009 09:23:48 -0400
>> Adam Chlipala <adamc at hcoop.net> wrote:
>>
>>
>>> Use Xen virtualization on both machines,
>>> so that we can create many virtual servers and move them among
>>> machines as needed.
>>>
>>
>> For our purposes, I recomend openvz virtualization.
>>
> 
> I can think of a few reasons why we might prefer Xen.  First, I think
> Xen is more popular, so it's more likely to have had folks spend time
> implementing features, and it's less likely to have bugs in established
> features.  Second, the less tight coupling of VMs seems like it should
> rule out some potential security problems.
> 
> I'm nowhere close to an expert on this subject, though.  I recognize the
> benefit of avoiding loading a separate kernel for each VM, and of
> avoiding the need to poke each VM to update the kernel.  I hope other
> folks will share their perspectives on the pros and cons of different
> virtualization tools.
> 
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