Greetings, I am observing a rather strange issue in the following setup: * 1 OpenLDAP master server (2.4.31) * 4 OpenLDAP slave servers (2.4.40) * The OpenLDAP slaves do forward any update attempt to the master using the chain overlay / proxyauthz (mainly to update the pwdFailureTime attribute for ppolicy) If I try to shut the master down (for maintenance let's say), the slaves behave properly, then begin to deadlock one after each other after a few minutes (by deadlock I mean no log output anymore, and any ldapwhoami / ldapsearch request connects and then times out) On the attached image, I monitored at the same time one of the slaves using collectd, to keep an eye on cn=monitor data (the period between 15:24:30 and 15:26:00 has been extrapolated by Grafana, no data is available at this time since cn=monitor access also deadlocks) I can see that backload / pending threads and waiters seem to increase gradually until the server gets unresponsive. I found nothing on the ML (except https://www.openldap.org/lists/openldap-technical/200912/msg00112.html) or searching for clues, Is this predictable behavior or and obvious misconfiguration, or it is an interesting occastion to dig a bit deeper ? Thanks in advance, -- Matthieu Cerda Infrastructure, BU Means @ NBS System