Failover issues
Simon Hobson
dhcp at thehobsons.co.uk
Tue May 30 22:14:28 UTC 2006
Shlomo Dubrowin wrote:
>OK, So I have failover configured and the primary is giving out leases as
>it should. Now, I want to test the failover. What I have been doing is
>shutting down the service on the primary and expecting the secondary to
>automatically take over. However, in the leases file on the secondary, I'm
>seeing that it believes it's own connectivity is down and not that of the
>primary. So, when the primary fails, the secondary thinks it has a problem
>with itself and doesn't give out leases. Any ideas why this isn't working
>as expected?
Does it by any chance go into "Communications interrupted" mode ?
I'm sure one of the failover experts will correct me if I'm wrong,
but the servers will not go into partner down mode automatically -
this is something you have to do manually. The reason given is that
there are failure modes (in particular, routing errors or failure of
an out-of-band inter server link) which can cause communications
interrupted but leave both servers able to communicate with clients -
having both server go into partner down and offering leases across
the whole range would result in "a certain amount of confusion".
Dig back through the archives, there's been a number of suggestions
for methods to monitor the peer and put the local server into partner
down via omapi (IIRC).
Simon
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