[Xen-users] Re: Differences in performance between file and LVM based images.

[Ligesh <myself@xxxxxxxxxx>]

On Wed, Aug 23, 2006 at 07:07:05PM +0200, Petersson, Mats wrote:
> > 
> > 
> >  Anyway, some benchmarks would be great. And I think this 
> > should be explicitly mentioned in the documentation. Primary 
> > purpose of virtualization is to squeeze the maximum out of 
> > hardware, and so we cannot really afford performance 
> > penalties arising from wrong implementation decisions.
> 
> I also don't agree that virtualization is (always) about squeezing the
> most performance out of the hardware. It is use-case for virtualization
> [for example merging multiple servers into one physical machine], but
> there are many other use-cases where other features given by
> virtualization is much more important. One of those would be security
> and the ability to migrate a guest from one physical machine to another.

 With LVMs the only issue is in setting it up. You will need do some jumping 
through hoops to get / on the LVM. But after that it is as flexible, and 
sometimes even easier to manage than plain files. So given that they are 
similar in terms of all other functionalities, to me it makes sense to use 
LVMs, since the performance improvement for LVMs comes without any other 
drawbacks.

 'Squeezing the max out of hardware' sounds cheap. What I meant was 'improving 
harware utilization', which I think is the declared aim of xen, as seen on 
xensource.com. Anyway, whatever be the scenario, creating unnecessary overheads 
is a bad idea. So maybe everyone can standardize on LVMs. The only problem is 
that DC's by default don't have LVMs, but as it becomes more popular, this 
would also be a non-issue. Having a small '/boot' and configure everything else 
as an LV seems a great idea to me, especially if it can be done at boot time. 
That is generally a good idea too, and not just for xen. 

 Thanks.

--
:: Ligesh :: http://ligesh.com 



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