I've just upgraded a test cluster from 18.2.4 to 19.2.0. Package install on centos 9 stream. Very smooth upgrade. Only one problem so far... The MGR restful api calls work fine. EXCEPT whenever the balancer kicks in to find any new plans. During the few seconds that the balancer takes to run, all REST calls seem to be completely dropped. The MGR log file normally logs the POST requests, but the ones during these few seconds don't appear at all. This causes our monitoring to keep raising alarms. The cluster is in a completely stable state, HEALTH_OK, very little activity, just the occasional scrubs. We use the restful API for monitoring (using the Ceph for Zabbix Agent 2 plugin, as Zabbix is the over-arching monitoring platform in the data centre). I haven't yet checked the memory leak problems that we (like many) were having, because I have been chasing this new problem. The problem is quite repeatable. To diagnose I use the zabbix_get utility to query every second. Whenever the MGR log file shows the balancer kick in the REST requests time out (after 3 seconds - not sure whether the utility or the MGR is timing them out - I suspect the utility). They normally complete after a small fraction of a second. With the balancer disabled the REST interface works reliably again. The problem does not occur pre-squid. Anyone any ideas, or shall I raise a bug? Thanks, Chris