Re: (ITS#5839) overlay glue

[rein@OpenLDAP.org]

LEHOUELLEUR, Marin wrote:

> Can you confirm your sentence is it "for the same consumer" or "from the same provider" that syncrepl may not behave properly ?

Both, i.e not "or" but "and"..

Each consumer can only have one syncrepl instance below a common glue 
database that replicates from the same provider. Multiple providers is 
OK as long as they all have different serverID (although this might 
require 2.4). Each provider can replicate to an unlimited number of clients.

If you configure syncrepl on both the glue database and a subordinate 
then syncrepl on the glue db will, when it start up, try to wipe out 
everything in the subordinate db (unless the content in the subordinate 
db is also replicated to syncrepl in the glue db, in which case the 
subordinate syncrepl is useless).

If you have two subordinate databases on a consumer that replicates from 
the same provider, then syncrepl on one of them can (when slapd start) 
pick up a newer sync cookie saved by the other without actually being in 
sync with the provider.  I.e it would miss some modifications.

> I'm about to deliver so if I have no misfunction with 2.3 when I test it, i may go with it.

I would definitely reconsider, unless you have an extremely good test 
scenario you are unlike to have tested all the pitfalls..   There can be 
som nasty race situations involved here.

> But I'm worried about the syncrepl bugs your talking about. Does two replica may support to feed about thirty (30) consumers as the DB is very little ??

The number of servers is no problem, it is the number of syncrepl 
instances on the same consumer that can cause problems as outlined above.

> Master replicates to two replica the full database. 30 Consumers plugged to the replicas with each a different login (SASL authentication).

No problem as long as you don't have more than one syncrepl instance on 
each server.

This ITS should probably be closed and further questions directed to the 
openldap-software list.

Rein