CARP on backup doesn't relinquish MASTER

Rudy Rucker crapsh at
Fri Jun 15 09:05:34 UTC 2007

Ah... put it will also failover all the OTHER carp interfaces on the box 
when a physical interface goes down....  I had read the man page as that 
being the ONLY feature of that sysctl variable.

    Allow virtual hosts to preempt each other.  It
    is also used to failover carp interfaces as a
    group.  When the option is enabled and one of
    the carp enabled physical interfaces goes down,
    advskew is changed to 240 on all carp interfaces.


Marko Lerota wrote:
> Rudy Rucker <crapsh at> writes:
>> I noticed that if I reboot a server that is the MASTER, the carp0 on
>> the BACKUP box goes into MASTER mode and stays that way -- even when
>> the real master machine has finished rebooting.  Is this a desired
>> trait to prevent CARP from switching IPs out of control?
> Yes, it depends of what you have put in 'net.inet.carp.preempt'
> if it's net.inet.carp.preempt=0 
> than the backap will become master and stays that way 
> and if it's net.inet.carp.preempt=1
> then the "real" master will take over the IP address from backup 
> server when he gets in the OK state 

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