General questions about failover, config changes and restarting

[James Dore]

> On 2 Mar 2016, at 17:21, S Ca <sjcarr at gmail.com> wrote:
> 
> On 2 March 2016 at 16:52, James Dore <james.dore at new.ox.ac.uk> wrote:> Hi Glenn,
>> I ask because we’ve had occasions in the past where I’ve restarted the first server, but left the second for a couple of hours, and we stop getting addresses issued to new clients. This is the kind of log message we get during this situation -
> 
> Sync is finished when both peers return to NORMAL mode. You need to
> restart both servers (just kill dhcpd and restart it) one after
> another or you're likely to run into issues with the pools not
> matching, and then you'll run into issues with not leasing IPs.
> 
> Steve

Yes, that has been my normal practice, but which ever order I restart the servers in, they never seem to sort themselves out first time round and require a handful of restarts apiece. 

My usual method is 

service dhcpd restart

given my SLES12 servers use systemd for service management now. although rcdhcpd restart achieves the same thing.

Any ideas why my servers need so many restarts? I try to leave them to settle for five or six minutes before trying again, but they just seem to stick with things like 

dhcpd.log-20151123:2015-11-23T10:17:58.203346+00:00 garibaldi dhcpd: failover peer newc-dhcp: I move from normal to shutdown
dhcpd.log-20151123:2015-11-23T10:18:03.848105+00:00 garibaldi dhcpd: failover peer newc-dhcp: I move from shutdown to startup
dhcpd.log-20151123:2015-11-23T10:18:03.854208+00:00 garibaldi dhcpd: failover peer newc-dhcp: peer moves from normal to communications-interrupted
dhcpd.log-20151123:2015-11-23T10:18:03.927644+00:00 garibaldi dhcpd: failover peer newc-dhcp: I move from startup to shutdown
dhcpd.log-20151123:2015-11-23T10:18:03.940208+00:00 garibaldi dhcpd: failover peer newc-dhcp: peer moves from communications-interrupted to partner-down

in the logs.

Cheers,
James