Failover on a large DHCP system

Brad Dameron Brad.Dameron at
Mon May 11 19:23:31 UTC 2009

I use omapi with 3.1.1 currently with 38k active leases without any issues. I add it to dhcp with omapi then I write it out to a global include file for restarts. The reason you are seeing it after a restart is because it get's wrote into the dhcpd.leases file. It will be removed from the lease file after a few rotations. It's not immediately. We currently use a 24 hour lease time. I haven't restarted my dhcp server in months and we add/remove statics quite a bit. If someone gives me an idea of what they need in a script I can convert my current perl script to be usable by the rest of the world.


From: dhcp-users-bounces at on behalf of Nicholas F Miller
Sent: Mon 5/11/2009 7:55 AM
To: dhcp-users at
Subject: RE: Failover on a large DHCP system

That was our original thought but after some testing and talk of 
omapi's demise and memory leaks I am hesitant to go the omapi route. 
 From our testing the changes made via omshell take precedence over 
the config even after a restart. This could be a real headache for 
trouble shooting. I think the best solution is to continue using 
restarts to add and remove hosts from DHCP. I took a more 
comprehensive look at our DHCP server and see that we only have around 
20,000 active leases during busy times and around 105,000 pool 
addresses. From what people have been saying here that isn't all that 
large of a load.

Nicholas Miller, ITS, University of Colorado at Boulder

On May 9, 2009, at 6:00 AM, dhcp-users-request at wrote:

> You could do both -- use omshell to make the changes, but also update
> dhcpd.conf.  That way you have the benefit of instant change without 
> reload
> and the security of a configuration file.

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