Torsten Schlabach (Tascel eG) wrote: > To begin with, I would just ask for confirmation of my proper > understanding of the documentation: > > 1. A master server is a server which is using the syncprov overlay > (servers/slapd/overlays/syncprov.c). This overlay will do little more > than just provide a synchronization cookie (CSN) which consumers may ask > for to find out what needs to get replicated and what not.
Pretty much, yes. We use the term "provider", not "master". > 2. A consumer server is a server in which an additional thread is > running which will query the master(s) in a given interval to ask for > updated and if any, get them over the wire and into the local copy of > the database. This synchronization thread is servers/slapd/syncrepl.c I > guess? There is no additional thread. In refreshOnly mode it will periodically ask for new updates; in refreshAndPersist mode it will keep an LDAP session open and receive updates as they occur. > 3. An N-Way Multi-Master setup is a setup in which N servers are each a > master and any of the others is a consumer of all other masters? N servers are each a provider; any of them can be consumers of any number of the other providers. Full NxN connectivity is not a requirement, nor does it scale well. > So what I fail to understand is: > > 1. What is the difference between Mirror Mode and N-Way Multi-Master? > Especially given that in N-Way Multi-Master, have to set olcMirrorMode > to TRUE. MirrorMode relies on an external frontend to direct all updates to a single provider. There is no difference within the OpenLDAP code between MirrorMode and MultiMaster; the difference is entirely external, based on your deployment. > 2. Given that I have added a 'Sync' value to the olcLogLevel attribute, > what would be the "health check" information I should be watching in the > log for to see that replication is attempted as expected. > 3. What problems should I be watching for in the logs? Error messages related to connect failures, retries, etc. > 4. Could I for example manually ask a master (using some ldapsearch > statement, pretending I was the consumer) what the master thinks which > entries I would have to update? Yes, use ldapsearch -E sync. See the ldapsearch(1) manpage. -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
