On Tue, Jan 22, 2008 at 11:36:58AM +0100, Damian Lubosch wrote:
> Hello XEN Admins!
> 
> Since two days I have huge problems with one DomU machine that loses its 
> network connection.
> I am runnung NetBSD4 stable with XEN 3.1.2 for DomU and NetBSD3.1 for 
> the DomUs. The dom0 itself has only internal network, all internet 
> network is routed through a domU router (which runs fine). The 
> problematic domU has both, an internal IP (to connect to the other 
> DomUs) and an external one for its service. I am using ifconfig alias to 
> set up the second IP.
> 
> The whole system ran once as XEN 2, in the end of December I updated the 
> whole system to XEN 3 and it ran for about 3 weeks. This domU is the 
> most active one in my environment. It uses two (system-)file-filesystems 
> and one on a real (data-)partition. It has also 466MB of RAM. The MAC 
> address is also starting with 00:16:3e. The domU kernel is standard from 
> NetBSD3.1
> 
> The problem is that only this specific DomU is not reachable by either 
> internal nor external network and sometimes I am not even able to login 
> through the console over the dom0.
> 
> In the dom0 "xm list" show a status of ------ (so no "b" as in the other 
> domUs)
> 
> As hardware I am using a AMD 3700+ with 1GB Ram and Hardware Raid.
> 
> I suspected probably the balloon driver to be the one causing problems. 
> Is it possible to completely switch it off? I just found (dom0-min-mem 
> 0) which will turn off "ballooning" for the dom0 only.
> Is netbsd perfectly capable of ballooning?

There's no balloon driver at all in NetBSD. All memory allocations to
domains are static.
But, the hypervisor is then unable to reclaim memory if it evers gets low.
How much free memory does xm info (or xm top) reports, and how many
virtual disk and network interfaces to you have in dom0 ?

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--