[CentOS] Re: Re: Not seeing all memory in CentOS 5.1 x86_64

Henry Ritzlmayr fedora-list at rc0.at
Wed Jun 11 17:18:20 UTC 2008

Am Mittwoch, den 11.06.2008, 11:36 -0400 schrieb Ruslan Sivak:
> Tim Verhoeven wrote:
> > On Wed, Jun 11, 2008 at 4:46 PM, Ruslan Sivak <russ at vshift.com> wrote:
> >   
> >> While it seems to make sense (and both xentop and virsh nodeinfo) show the
> >> right amount of memory, even when I shut down one of the VM's, free and top
> >> still think I only have 6GB of ram.
> >>     
> >
> > That is normal, the memory that was used by VM's is not automatically
> > returned to the dom0 and therefore won't show when running free and
> > top.
> >
> > Regards,
> > Tim
> >
> >   
> I guess it has something to do with the ballooning driver for Dom0.  It 
> looks like I just tried to allocation too much memory to DomU and the 
> box went down hard.  I think there's a setting in xen to the min amount 
> of memory to go down to, but I'm not sure why Dom0 is using 600mb of 
> RAM.  Is there a mini installation of CentOS that I can do that would 
> use less RAM?  I've already unchecked all the boxes when installing 
> CentOS. I would like Dom0 to be as small as possible, both due to RAM 
> usage and from a security perspective. 
> Russ

The option you think of is called dom0-min-mem and can be found
in /etc/xen/xend-config.sxp
Regarding to a mini installation of CentOS - not that I know of, but you
must have some daemons running, since on my installations here DOM0 only
consumes 373MB and I have postfix running on DOM0 as well. 


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