Failover configuration (was failover stability?)

[Keith Lawson]

>>>David_Hankins at isc.org 07/05/06 12:28 pm >>> 
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. 

Here's the log lines I saw on the secondary when this was happening: 

Jul  5 10:25:00 pita.lhsc.on.ca dhcpd: [ID 702911 daemon.info]
DHCPREQUEST for 142.158.20.221 from 00:08:02:f9
:f2:8d via 142.158.20.250: lease 142.158.20.221 unavailable.
Jul  5 10:25:00 pita.lhsc.on.ca dhcpd: [ID 702911 daemon.info] DHCPNAK
on 142.158.20.221 to 00:08:02:f9:f2:8d
via 142.158.20.250
Jul  5 10:25:00 pita.lhsc.on.ca dhcpd: [ID 702911 daemon.info]
DHCPREQUEST for 142.158.20.221 from 00:08:02:f9
:f2:8d via 142.158.20.251: lease 142.158.20.221 unavailable.
Jul  5 10:25:00 pita.lhsc.on.ca dhcpd: [ID 702911 daemon.info] DHCPNAK
on 142.158.20.221 to 00:08:02:f9:f2:8d
via 142.158.20.251
Jul  5 10:25:01 pita.lhsc.on.ca dhcpd: [ID 702911 daemon.error]
DHCPDISCOVER from 00:08:02:f9:f2:8d via 142.15
8.20.251: peer holds all free leases

Here's the closest "pool" line to that time: 

Jul  5 10:33:34 pita.lhsc.on.ca dhcpd: [ID 702911 daemon.info] pool
1724c8 142.158.20/24 total 50  free 20  backup 19  lts 0

I dind't have "default-lease-time" and "max-lease-time" set in my conf
file. Since I've set them I've been unable to reproduce the problem. 
 
>Are you sure your servers are operating in 'normal' failover state?  
>Once they connect for the first time, the primary should give away 
>half its free leases to the secondary (moving them to 'backup' state). 

Yes they were in normal state. The pool for this subnet has never been
used up and my "lts" value has never been greater (or less) than "-2". 
 
>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. 

Thanks for the suggestion, will do. 
 

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