Subject: Re: [vserver] Pros and Cons of 32/64bit guests on 64bit host
From: Ed W <lists@wildgooses.com>
Date: Thu, 21 Aug 2008 22:17:20 +0100
Thu, 21 Aug 2008 22:17:20 +0100
Stephen Liu wrote:
> Hi Nicolas,
>
>
> --- Nicolas Cadou <ncadou@cobi.net> wrote:
>  
>   
>> The 64 bit host now happily runs several virtual machines (of the KVM
>> kind) ..
>>     
>
> Could you please shed me some light of the setup of running several VMs
> on one host?  Whether install all VMs such as KVM, OpenVZ, vserver,
> Xen, VMware etc. on the host?  Would it needs extra RAM?  Would there
> be any conflict?  TIA
>
>
>   

KVM/Xen/VMware aren't sharing kind of virtualisation - with these you 
allocate a chunk of the real machine and it's not so easy to overcommit 
(I believe).  So you kind of allocate XYZ MB to each virtual machine and 
you roughly have to live with that commitment

VServer and OpenVZ are much less rigid virtualisations (but they have 
some features to limit resources if needed).  It makes it much easier to 
overcommit the hardware (for better or worse)

Since the former are kind of complete machine emulations I would assume 
it's no problem to run vserver under a kvm/vmware image.  On the other 
hand there is no way to run Windows under a vserver image since it's 
really just a fancy chroot system (plus some other features)

Does that help?

Ed W


Stephen Liu wrote:
Hi Nicolas,


--- Nicolas Cadou <ncadou@cobi.net> wrote:
 
  
The 64 bit host now happily runs several virtual machines (of the KVM
kind) ..
    

Could you please shed me some light of the setup of running several VMs
on one host?  Whether install all VMs such as KVM, OpenVZ, vserver,
Xen, VMware etc. on the host?  Would it needs extra RAM?  Would there
be any conflict?  TIA


  

KVM/Xen/VMware aren't sharing kind of virtualisation - with these you allocate a chunk of the real machine and it's not so easy to overcommit (I believe).  So you kind of allocate XYZ MB to each virtual machine and you roughly have to live with that commitment

VServer and OpenVZ are much less rigid virtualisations (but they have some features to limit resources if needed).  It makes it much easier to overcommit the hardware (for better or worse)

Since the former are kind of complete machine emulations I would assume it's no problem to run vserver under a kvm/vmware image.  On the other hand there is no way to run Windows under a vserver image since it's really just a fancy chroot system (plus some other features)

Does that help?

Ed W