> Sounds like sync-repl (for replication) and chain overlay (see 'man
> slap-chain') will do what you want.

But what happens when one of the servers is down, does slapo-chain store the
values ?

chain + sync cant handle any request if master is down.

I made some modifications before so that a client will change into master and other clients will connect to it in case master is down, but it is only academic.

the architecture "HA + LB cluster" has been rised long before, but it seems openldap team doesnt implement it gracefully yet :-(