[TriLUG] Xen questions

[Jason Tower]

all depends on what you want the domU to do.  a stripped down install can 
easily run in 32mb.  it's the apps that eat up ram.

and if you have to beg your manager for a $30 stick of ram, maybe you should 
take advantage of the have a job/need a job session at the next meeting :)

Owen Berry wrote:
> Thanks for the reply Jason. One concern of mine is the amount of memory
> that I have. I seem to remember you talking about a stripped down domU
> two meetings ago. Any tips? Or should I beg my manager for more memory?
> 
> Owen
> 
> On Tue, Aug 29, 2006 at 03:22:33PM -0400, Jason Tower wrote:
> 
>>xen would be perfect for your needs.  your host OS (dom0 in xen terms) 
>>should run fc5 as it is very easy to get xen running.  you'll need 
>>128-256mb for the dom0 plus whatever ram you want to allocate to each guest 
>>OS (domU in xen terms).
>>
>>the hardest part is setting up the root filesystem for the domU, for centos 
>>you'd probably use yum with the --installroot=/some/path option (i think 
>>that's right).  you can either compile your own xenified centos kernel or 
>>use a stock fc5 domU kernel (i do the latter with my ubuntu domUs and it 
>>works fine).
>>
>>the default network mode is bridge, so each domU will get its own ip 
>>address just like the dom0.  there are also nat and route modes but 
>>bridging is what 98% of people want.
>>
>>http://www.fedoraproject.org/wiki/FedoraXenQuickstart
>>
>>jason
>>
>>Owen Berry wrote:
>>
>>>Some questions for those Xen and virtualization gurus out there. First,
>>>some background. I run Fedora Core 4 on my workstation, but a lot of
>>>what I develop ends up running on RHEL3/4 servers. Every now and then I
>>>have problems because of differences in Perl modules or packaging on the
>>>"production" machines. I suspect these problems will get worse over time
>>>as I'm "forced" to move to more recent versions of Fedora.
>>>
>>>I'm wondering if I could improve my lot by using Xen to setup CentOS
>>>virtual hosts on my development machine, to more closely replicate the
>>>production machines. Xen appeals to me over other VM techniques
>>>because of it's low overhead - I have a decent workstation but it's
>>>still single CPU and 512M ram.
>>>
>>>1) Is this something that Xen would be good for?
>>>2) Am I right in thinking that Xen would be a good virtualization
>>>  choice? I have a VMWare license, but I'm thinking it'll take too much
>>>  in the way of resources.
>>>3) Sometimes people need to access my web server. Will I be able to
>>>  forward connections to a virtual machine, possibly using mod_proxy on
>>>  Apache. Or is there a more seemless way to do this? Not sure how
>>>  networking works in Xen, and assuming something similar to VMWare.
>>>4) I'm thinking it would be beneficial to upgrade from FC4 to FC5 before
>>>  trying out Xen. Sound right?
>>>
>>>BTW, I don't really want to convert my workstation to running CentOS so
>>>please don't suggest it, unless you feel you have to. :-)
>>>
>>>TIA,
>>>Owen