Colleagues, if you have enough dummy checks (mine: 320,000) with an IDO master and an Icinga DB one, the IDO one will accumulate pending writes:

[root@aklimov820479-1 ~]# while curl -fsSku root:f60c53973dbe11:21:01 [692/710] cept: application/json' -d '{"attrs":["pending_outgoing_messages"]}' 'https://1 0.27.2.188:5665/v1/objects/endpoints'; do sleep 5m; done {"results":[{"attrs":{"pending_outgoing_messages":0},"joins":{},"meta":{},"name ":"master1","type":"Endpoint"},{"attrs":{"pending_outgoing_messages":3033671}," joins":{},"meta":{},"name":"master2","type":"Endpoint"}]}{"results":[{"attrs":{ "pending_outgoing_messages":0},"joins":{},"meta":{},"name":"master1","type":"En dpoint"},{"attrs":{"pending_outgoing_messages":3331043},"joins":{},"meta":{},"n ame":"master2","type":"Endpoint"}]}{"results":[{"attrs":{"pending_outgoing_mess ages":0},"joins":{},"meta":{},"name":"master1","type":"Endpoint"},{"attrs":{"pe nding_outgoing_messages":3588325},"joins":{},"meta":{},"name":"master2","type": "Endpoint"}]}{"results":[{"attrs":{"pending_outgoing_messages":0},"joins":{},"m eta":{},"name":"master1","type":"Endpoint"},{"attrs":{"pending_outgoing_message s":3818835},"joins":{},"meta":{},"name":"master2","type":"Endpoint"}]}{"results ":[{"attrs":{"pending_outgoing_messages":0},"joins":{},"meta":{},"name":"master 1","type":"Endpoint"},{"attrs":{"pending_outgoing_messages":4083728},"joins":{} ,"meta":{},"name":"master2","type":"Endpoint"}]}{"results":[{"attrs":{"pending_ outgoing_messages":0},"joins":{},"meta":{},"name":"master1","type":"Endpoint"}, {"attrs":{"pending_outgoing_messages":4389195},"joins":{},"meta":{},"name":"mas ter2","type":"Endpoint"}]}{"results":[{"attrs":{"pending_outgoing_messages":0}, "joins":{},"meta":{},"name":"master1","type":"Endpoint"},{"attrs":{"pending_out going_messages":4627411},"joins":{},"meta":{},"name":"master2","type":"Endpoint "}]}{"results":[{"attrs":{"pending_outgoing_messages":0},"joins":{},"meta":{}," name":"master1","type":"Endpoint"},{"attrs":{"pending_outgoing_messages":482323 4},"joins":{},"meta":{},"name":"master2","type":"Endpoint"}]}{"results":[{"attr s":{"pending_outgoing_messages":0},"joins":{},"meta":{},"name":"master1","type" :"Endpoint"},{"attrs":{"pending_outgoing_messages":5001852},"joins":{},"meta":{ },"name":"master2","type":"Endpoint"}]}{"results":[{"attrs":{"pending_outgoing_ messages":0},"joins":{},"meta":{},"name":"master1","type":"Endpoint"},{"attrs": {"pending_outgoing_messages":5219258},"joins":{},"meta":{},"name":"master2","ty pe":"Endpoint"}]}{"results":[{"attrs":{"pending_outgoing_messages":0},"joins":{ },"meta":{},"name":"master1","type":"Endpoint"},{"attrs":{"pending_outgoing_mes sages":5501339},"joins":{},"meta":{},"name":"master2","type":"Endpoint"}]}{"res ults":[{"attrs":{"pending_outgoing_messages":0},"joins":{},"meta":{},"name":"ma ster1","type":"Endpoint"},{"attrs":{"pending_outgoing_messages":5722573},"joins ":{},"meta":{},"name":"master2","type":"Endpoint"}]}{"results":[{"attrs":{"pend ing_outgoing_messages":0},"joins":{},"meta":{},"name":"master1","type":"Endpoin t"},{"attrs":{"pending_outgoing_messages":5912916},"joins":{},"meta":{},"name": "master2","type":"Endpoint"}]}{"results":[{"attrs":{"pending_outgoing_messages" :0},"joins":{},"meta":{},"name":"master1","type":"Endpoint"},{"attrs":{"pending _outgoing_messages":6117871},"joins":{},"meta":{},"name":"master2","type":"Endp oint"}]}{"results":[{"attrs":{"pending_outgoing_messages":0},"joins":{},"meta": {},"name":"master1","type":"Endpoint"},{"attrs":{"pending_outgoing_messages":63 82224},"joins":{},"meta":{},"name":"master2","type":"Endpoint"}]}{"results":[{" attrs":{"pending_outgoing_messages":0},"joins":{},"meta":{},"name":"master1","t ype":"Endpoint"},{"attrs":{"pending_outgoing_messages":6697645},"joins":{},"met a":{},"name":"master2","type":"Endpoint"}]}{"results":[{"attrs":{"pending_outgo

Or pending reads on Icinga DB site. Idk so far. Don't forget to test with a non-default maxmemory policy for Redis and the Blackhole engine for the IDO schema (ex. schema table), or you'll run OOM.

Please try to format this in a more readable way. It also contains copy & paste errors, for example -fsSku root:f60c53973dbe11:21:01 [692/710] cept: application/json'.