dhcpd stuck in recover mode

Tobias Winter tobias at linuxdingsda.de
Tue Sep 13 09:19:59 UTC 2011

Hi list,

we are using the isc-dhcp-server package from debian squeeze 64bit in a
OMAPI failover setup.

The servers are configured to have one shared network in which the
following is configured:
- one subnet with a pool of ips for unknown computers
- some /32 subnets for already known computers with fixed ips

The pool of ips for unknown computers has the failover peer flag added
so it is balanced across both dhcpds and no conflicting dhcp leases will

After new hosts are known, they will get a fixed ip and need to be added
to the dhcpd.conf. After recreating the config files, both dhcpds are
restarted after each other. first the primary one, then the secondary one.

Normally the secondary detects that the peer dhcp disconnected, it moves
from normal to communications interrupted, then it detects that the peer
moves from normal to normal and will also move from
communications-interrupted to normal. After that, balancing of the
failover pool takes place and the setup is once again in a consistent state.

My problem is, that sometimes both servers get stuck in recover or
recover-done mode and will not jump to a normal mode of operations.
If that is the case, they will happily continue to serve the fixed ips
for known hosts, but will no longer hand out dynamic ips from the
failover pool since they are in recover mode.

Is there any way to see why the server hangs in recover or recover-wait?

Is it possible to force the dhcpd to normal mode again?

Can the log verbosity be increased to give better insight as to what is
going on while they are trying to recover?

I went through the mailing list archive and googled quite a lot, but I
can't seem to get something useful out of it. Any help would be greatly

- Tobias

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