openstack team mailing list archive

[Vishvananda Ishaya <vishvananda@xxxxxxxxx>]

On Oct 12, 2012, at 10:33 AM, Justin Hurley <justin.hurley@xxxxxxxxxxx> wrote:

> Hello All,
>  
> I am having problems with some instances not receiving DCHPACK from my VM's dhcp server after extended periods of time. These instances are running heavy network, I/O, and RAM loads when the DHCPREQUEST does not receive a response. Note that this only happens to a handful of instances, not all instances running the exact same load. I have printed a relevant section of the syslog below.
>  
> My current environment is a multi-host flat dhcp network with nova-network running on each node. All servers and VM's are running Ubuntu 12.04 and using kvm/libvirt. I am also using large NFS servers to transfer big files to and from instances across the VM network.
>  
> In the past, I used Eucalyptus and the same problem would occur. This tends to happen more frequently with more VMs and overall network load.
>  
> If anyone has any ideas as to why the dhcp server stops responding to only a few instances occasionally please let me know.

I haven't seen this before, but you may be able to work around the issue by setting much longer leases:


force_dhcp_release=True
dhcp_lease_time=86400 # 1 day leases
fixed_ip_disassociate_timout=172800 # 2 day timeout


Vish