Re: [Xen-users] Xen Setup

["Todd Deshane" <deshantm@xxxxxxxxx>]

On Wed, Aug 6, 2008 at 11:56 AM, Alan <alan@xxxxxxxxxxxxx> wrote:
> Hi All,
>
>
>
> I am interested in deploying Xen to replace an existing Virtuozzo based
> virtual server solution we are currently using. However due to the
> differences in how it works etc., I would like some clarification on our
> proposed setup:
>
>
>
> Firstly, what is the recommended OS for running Xen? We are thinking of
> using 32bit CentOS 5 as the dom0 OS and probably CentOS 5 domUs as well.
>

CentOS base and CentOS guests are well-supported and known to work.

There really isn't a recommended OS, it is more a matter of preference.

It may also matter what support, applications or scenarios you hope to
achieve, but more likely it is a matter a preference.

>
>
> Secondly, due to using a 32bit OS, technically we'd be limited to using 4GB
> ram in the server but I have read Xen is capable of utilising PAE on 32bit
> systems to utilise more than 4GB ram. So in this case, we would like to use
> 8GB of ram to split up amongst the Xen VPSes. Will this be fine? Or will Xen
> not utilise the full 8GB available?
>
>

Xen 32bit + PAE  on CentOS supported up to 16 GB of RAM last I heard and
saw in the CentOS virtualization docs.

Xen will reserve a small amount for the management domain and the hypervisor
itself, the rest can be used for guests.


>
> Lastly, we need to be able to "upgrade" and "downgrade" a VPS's disk space
> easily. Under Virtuozzo all we need to do is change the number of disk
> blocks allocated and reboot the VPS. Can we do something similar with Xen,
> for instance using LVM partitions? I have read you can either allocate a
> normal non-LVM partition, a LVM partition or a file based partition as the
> "disk" for the VPS. I am looking for a way to easily increase or decrease
> the space a VPS has without having to be fiddling with partition tables and
> resizing manually using fdisk.
>
>

Xen can work similarly with LVM partitions.


I am curious about the application load, is it disk intensive?

Also, are you switching to Xen to gain performance isolation properties?

For simply pure performance I would expect openVZ to be better in general,
but if you need the isolation properties and performance, then Xen is a good
choice.


Hope that helps,
Todd

-- 
Todd Deshane
http://todddeshane.net
check out our book: http://runningxen.com

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