I was speaking with Howard in person last week at LDAPCon about the problems I might hit if I wanted to run hundreds of replicas off a single master.  If I heard right, Howard told me that OpenLDAP uses a single thread for replication, and therefore processes each replica in a serial fashion, one at a time.  If any replica is going slowly (high network latency for example), it would have a knock-on effect to the time it takes to get changes replicated across the whole estate.


We have an aggressive target to meet - updates out in 5 minutes.  Updates are small, but alarm bells are now ringing in my head about OpenLDAP’s ability to deliver this.


This leads to a couple of questions:


1 - How easy would it be to patch OpenLDAP 2.4 to get the master to use multiple threads for replication?  Is that a reasonably straightforward fix, or is this quite a sizeable architectural change?


2 - If my master server has 40 cores, would there be mileage in setting up a number of slapd processes (say 10) on the same host, bound to different sockets, all acting as first-level replicas, and then all the replicas fanning out across the WAN synchronise from these processes rather than from the master process?  That would be a way, I suppose, of getting the master server to make better use of the available cores to get updates out quicker?





NOTICE: Morgan Stanley is not acting as a municipal advisor and the opinions or views contained herein are not intended to be, and do not constitute, advice within the meaning of Section 975 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. If you have received this communication in error, please destroy all electronic and paper copies; do not disclose, use or act upon the information; and notify the sender immediately. Mistransmission is not intended to waive confidentiality or privilege. Morgan Stanley reserves the right, to the extent permitted under applicable law, to monitor electronic communications. This message is subject to terms available at the following link: http://www.morganstanley.com/disclaimers If you cannot access these links, please notify us by reply message and we will send the contents to you. By messaging with Morgan Stanley you consent to the foregoing.