[Cialug] RAM and virtualization

[Thomas Kula]

On Mon, Sep 24, 2007 at 11:09:55AM -0500, Jeff Davis wrote:
> 
> Can anyone (Theron?) comment on allocating RAM in a Xen or VMware setup?
> 
> If I have say 4G physical RAM, can I allocate a total of more than
> 4G of RAM across the vms without any detrimental effects?  If I
> only have a total allocated of 4G I think I'm losing some of the
> capability of the virtualization my not allowing the vm layer
> to manage that for me.  What if I build in a fudge factor of say 1.5 times
> my physical ram and allocate 6G?  Are there any standards you use for this?
> 
> Also, do you allocate more ram for the dom0?

With Xen at least, you can not over-allocate RAM --- if a domU 
is running, its allocated RAM is taken up completely.          

As for the dom0, I watched memory usage on it and gave it enough
that it used most of it w/o going into swap. 

-- 
Thomas L. Kula | kula at tproa.net | http://kula.tproa.net/
Mathom House at Ypsi-Edge, The People's Republic of Ames