Subject: Re: [vserver] Newbei's questions
From: Martin <inkubus@interalpha.co.uk>
Date: Tue, 15 Apr 2008 10:24:09 +0100

On Tue, 2008-04-15 at 15:39 +0800, Stephen Liu wrote:
> Hi folks,
> 
> 
> Linux-VServer and FreeVPS are complete new to me.  Just came across
> them on Internet browsing.  Having read the FAQ of the former briefly. 
> Still have following questiong unsolved;
> 
> 
> 1)
> What will be the advantage in running Vserver compared to
> Xen/VirtualBox/VMWare/etc.  IIRC on FAQ it mentiones Vserver taking
> only Windows Guest.  The others can take Windows guest additional to
> Linux/Unix guests.
Vserver abstracts things at a higher level than Xen et al.  They provide
you with a virtual computer, while vserver provides you with
(essentially) a virtual userland.  This means that vserver is lower
overhead (it doesn't need a separate kernel per instance, also because
it 'is aware' of OS abstractions like file systems, it can do things
like vhashify), is more tighly intergrated (from the host machine it's
essentially one *NIX boxen), can manage resources in a much more fine
grained manner and doesn't suffer from some of the 'clashing' problems
that virtual machines do (i.e. both the kernel and emulated kernel have
their own memory management systems, neither of which was designed to be
heirarchical).  On the flip side, you are limited to a Linux style
userland in the guests.

They are very different tools, aimed at solving different problems.  If
you have a large number of Linux boxen you wish to consolidate / plan to
deploy a large number of boxen then vserver can make the management of
them easier and reduce the hardware requirements.  If you want to run
multiple, distinct, uncoperative OSs on the same hardware - then you
need one of the virtual machine style systems.

> 2)
> What are the major difference between VServer and FreeVPS

They are both doing the same /conceptual/ thing.  The differences are in
how it's achieved and how they are implemented.  Last I looked FreeVPS
had a fully virtualised network stack (more costly but more flexible)
while VServer had IP level separation (simplier and faster but less
flexible) but I know this has been an active area of development so that
may no longer be true.  Conversely I don't think (last time I looked)
FreeVPS had an equivalent of vhashify.  It was a while since I checked
the actual feature lists so I may well be wrong.

HTH

Cheers,
 - Martin