[ceph-users] increasing PGs OOM kill SSD OSDs (octopus) - unstable OSD behavior

Hi, today I wanted to increase the PGs from 2k -> 4k and random OSDs went offline in the cluster. After some investigation we saw, that the OSDs got OOM killed (I've seen a host that went from 90GB used memory to 190GB before OOM kills happen). We have around 24 SSD OSDs per host and 128GB/190GB/265GB memory in these hosts. All of them experienced OOM kills. All hosts are octopus / ubuntu 20.04. And on every step new OSDs crashed with OOM. (We now set the pg_num/pgp_num to 2516 to stop the process). The OSD logs do not show anything why this might happen. Some OSDs also segfault. I now started to stop all OSDs on a host, and do a "ceph-bluestore-tool repair" and a "ceph-kvstore-tool bluestore-kv compact" on all OSDs. This takes for the 8GB OSDs around 30 minutes. When I start the OSDs I instantly get a lot of slow OPS from all the other OSDs when the OSD come up (the 8TB OSDs take around 10 minutes with "load_pgs". I am unsure what I can do to restore normal cluster performance. Any ideas or suggestions or maybe even known bugs? Maybe a line for what I can search in the logs. Cheers Boris