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Re: MirrorMode behind fail over loadbalancer

Diaa Radwan wrote:
We have two openldap 2.4.7 , configured as MirrorMode, We are planning
to add load balancer in front of both servers into the production
environment, We don't want too go through conflicts issues as it was
stated before as messy process.

--------- --------- . . . . . Srv1 . . Srv2 . --------- --------- \ / ---- ------------ . LoadB . .-------.

As per my understanding, the load balancer(failover mode) is
redirecting all traffic to the active server(srv1); if the active
server went down the traffic will be redirected to stand-by
server(srv2). When srv1 goes online again the load balancer will
redirect all trafic to srv1, while srv1 is in progress to get synced
with srv2. The load balancer will not consider the sync process; it
will just redirect the traffic.

it was previously stated on the mailing list that there should be one
write at a time. is there any conflict will occur when server getting
bulk syncing and receiving updates(attribute level)/add requests as

What happen if there attribute-level conflict? how to avoid it?
suggestions are highly welcomed.

I would recommend the LB only redirects when the server it is *currently* pointing to goes down.

That way, if svr1 goes down, svr2 becomes active. When svr1 comes back, it resynchronises and is ready and waiting to take over should svr2 go down.

If you immediately switch and you have some hardware failure that has caused corruptions or other things on svr1, then it would be unwise for that to become the active node until you have fully investigated why it went down in the first place.


Kind Regards,

Gavin Henry.
Managing Director.

T +44 (0) 1224 279484
M +44 (0) 7930 323266
F +44 (0) 1224 824887
E ghenry@suretecsystems.com

Open Source. Open Solutions(tm).