Re: ISC DHCP server failover

[Blake Covarrubias <blake () beamspeed com>]

On Mar 17, 2010, at 7:22 AM, Dan White wrote:

> We've experienced two types of problems from time to time:
>
>  The servers stop balancing their addresses, and one server starts to
> exhibit 'peer holds all free leases' in its logs, in which case we need to
> restart the dhcpd process(es) to force a rebalance.

We experience this problem from time to time as well, and I have yet to find its cause. We also 'fix' it by restarting 
the dhcpd daemon.

>  In some cases, and I'm not sure which equipment may be to blame, if one
> server goes down then the other server will not hand out addresses to
> clients which had originally received addresses from the failed server.
> We've dealt with that by balancing our lease times with our MTTR for a
> failed server.

From the dhcpd.conf man page it seems the solution to this problem is to put the remaining active server into the 
PARTNER-DOWN state.


Aside from the 'peer holds all free leases' error Dan mentioned, ISC DHCP's load balancing and failover has worked very 
well for us.

--
Blake Covarrubias