Failover stability?

Ken Eddings eddingsk at
Wed Jul 5 20:05:18 UTC 2006

At 9:28 AM -0700 7/5/06, David W. Hankins wrote:
>On Tue, Jul 04, 2006 at 02:05:13PM -0400, Keith Lawson wrote:
>> I'm just wondering what the state is of master/slave peer failover. Is
>> failover stable enough to be used in a production environment now?
>> I've been testing using 3.0.4 one one subnet  and I'm running into a
>> scenario where the master load balances a request to the slave. The
>> slave then ignores the request and logs a "peer holds all free leases"
>> message. I've been reading through the mailing list archives and
>> indications are that these problems are supposed to be resolved in 3.0.4
>> but that doesn't seem to be the case.
>Something's going wrong with your setup.  That log line tells me
>that your secondary thinks all the leases are in the 'free' state.

First thing I think of is the clocks are too far out of sync.  That's been the case every time I've heard the "peer holds all free leases" report.

>Are you sure your servers are operating in 'normal' failover state?

If there were an easier way to see this it would probably help on troubleshooting.

>Once they connect for the first time, the primary should give away
>half its free leases to the secondary (moving them to 'backup' state).
>Make sure both your servers are using precisely the same configuration
>file (modulo failover {} config bits which have to be different).
>The easiest way to do that is to make dhcpd.conf contain only the
>failover config, and to move the rest of the config to a separate
>file ("dhcpd.common.conf", say), then use an include directive:
>	include "dhcpd.common.conf";
>Then just copy this file between servers to keep it consistent.
>David W. Hankins		"If you don't do it right the first time,
>Software Engineer			you'll just have to do it again."
>Internet Systems Consortium, Inc.		-- Jack T. Hankins

Ken Eddings, Hostmaster, IS&T,   eddingsk at,   eddingsk at
   Work:+1 408 974-4286, Cell: +1 408 425-3639, Fax: +1 408 974-3103
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