Hi David,
here are my findings so far:
installed on the server Elastic Search 6.1.1 - no change
found only one log file as below:
[2023-04-07T16:08:18,190][WARN ][o.e.b.JNANatives ] Unable to lock JVM Memory: error=12, reason=Cannot allocate memory
[2023-04-07T16:08:18,197][WARN ][o.e.b.JNANatives ] This can result in part of the JVM being swapped out.
[2023-04-07T16:08:18,197][WARN ][o.e.b.JNANatives ] Increase RLIMIT_MEMLOCK, soft limit: 8388608, hard limit: 8388608
[2023-04-07T16:08:18,198][WARN ][o.e.b.JNANatives ] These can be adjusted by modifying /etc/security/limits.conf, for example:
# allow user 'elasticsearch' mlockall
elasticsearch soft memlock unlimited
elasticsearch hard memlock unlimited
[2023-04-07T16:08:18,198][WARN ][o.e.b.JNANatives ] If you are logged in interactively, you will have to re-login for the new limits to take effect.
[2023-04-07T16:08:18,880][INFO ][o.e.n.Node ] [node1] initializing ...
[2023-04-07T16:08:19,155][INFO ][o.e.e.NodeEnvironment ] [node1] using [1] data paths, mounts [[/usr/share/elasticsearch/data (/dev/sda)]], net usable_space [181.2gb], net total_space [396.6gb], types [ext4]
[2023-04-07T16:08:19,156][INFO ][o.e.e.NodeEnvironment ] [node1] heap size [1.9gb], compressed ordinary object pointers [true]
[2023-04-07T16:08:19,192][INFO ][o.e.n.Node ] [node1] node name [node1], node ID [s8iRMIM6Q1mWVOSv3g5BYw]
[2023-04-07T16:08:19,193][INFO ][o.e.n.Node ] [node1] version[6.1.1], pid[1], build[bd92e7f/2017-12-17T20:23:25.338Z], OS[Linux/5.19.0-35-generic/amd64], JVM[Oracle Corporation/OpenJDK 64-Bit Server VM/1.8.0_151/25.151-b12]
[2023-04-07T16:08:19,193][INFO ][o.e.n.Node ] [node1] JVM arguments [-Xms1g, -Xmx1g, -XX:+UseConcMarkSweepGC, -XX:CMSInitiatingOccupancyFraction=75, -XX:+UseCMSInitiatingOccupancyOnly, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -XX:+HeapDumpOnOutOfMemoryError, -Des.cgroups.hierarchy.override=/, -Xms2g, -Xmx2g, -Des.path.home=/usr/share/elasticsearch, -Des.path.conf=/usr/share/elasticsearch/config]
[2023-04-07T16:08:22,685][INFO ][o.e.p.PluginsService ] [node1] loaded module [aggs-matrix-stats]
[2023-04-07T16:08:22,685][INFO ][o.e.p.PluginsService ] [node1] loaded module [analysis-common]
[2023-04-07T16:08:22,685][INFO ][o.e.p.PluginsService ] [node1] loaded module [ingest-common]
[2023-04-07T16:08:22,685][INFO ][o.e.p.PluginsService ] [node1] loaded module [lang-expression]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [lang-mustache]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [lang-painless]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [mapper-extras]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [parent-join]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [percolator]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [reindex]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [repository-url]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [transport-netty4]
[2023-04-07T16:08:22,686][INFO ][o.e.p.PluginsService ] [node1] loaded module [tribe]
[2023-04-07T16:08:22,687][INFO ][o.e.p.PluginsService ] [node1] loaded plugin [ingest-geoip]
[2023-04-07T16:08:22,687][INFO ][o.e.p.PluginsService ] [node1] loaded plugin [ingest-user-agent]
[2023-04-07T16:08:29,809][INFO ][o.e.d.DiscoveryModule ] [node1] using discovery type [zen]
[2023-04-07T16:08:30,591][INFO ][o.e.n.Node ] [node1] initialized
[2023-04-07T16:08:30,596][INFO ][o.e.n.Node ] [node1] starting ...
[2023-04-07T16:08:30,765][INFO ][o.e.t.TransportService ] [node1] publish_address {127.0.0.1:9300}, bound_addresses {127.0.0.1:9300}
[2023-04-07T16:08:30,786][WARN ][o.e.b.BootstrapChecks ] [node1] memory locking requested for elasticsearch process but memory is not locked
[2023-04-07T16:08:33,848][INFO ][o.e.c.s.MasterService ] [node1] zen-disco-elected-as-master ([0] nodes joined), reason: new_master {node1}{s8iRMIM6Q1mWVOSv3g5BYw}{9cjFui0YRGeArVOR0nNvxw}{127.0.0.1}{127.0.0.1:9300}
[2023-04-07T16:08:33,868][INFO ][o.e.c.s.ClusterApplierService] [node1] new_master {node1}{s8iRMIM6Q1mWVOSv3g5BYw}{9cjFui0YRGeArVOR0nNvxw}{127.0.0.1}{127.0.0.1:9300}, reason: apply cluster state (from master [master {node1}{s8iRMIM6Q1mWVOSv3g5BYw}{9cjFui0YRGeArVOR0nNvxw}{127.0.0.1}{127.0.0.1:9300} committed version [1] source [zen-disco-elected-as-master ([0] nodes joined)]])
[2023-04-07T16:08:33,929][INFO ][o.e.h.n.Netty4HttpServerTransport] [node1] publish_address {172.21.0.3:9200}, bound_addresses {0.0.0.0:9200}
[2023-04-07T16:08:33,929][INFO ][o.e.n.Node ] [node1] started
[2023-04-07T16:08:34,391][INFO ][o.e.c.s.ClusterSettings ] [node1] updating [action.destructive_requires_name] from [false] to [true]
[2023-04-07T16:08:34,444][INFO ][o.e.g.GatewayService ] [node1] recovered [2] indices into cluster_state
[2023-04-07T16:08:35,719][INFO ][o.e.c.r.a.AllocationService] [node1] Cluster health status changed from [RED] to [YELLOW] (reason: [shards started [[app][4]] ...]).
[2023-05-22T05:46:30,447][WARN ][o.e.d.c.ParseField ] Deprecated field [all_fields] used, replaced by [Set [fields] to `*` instead]
[2023-05-22T05:46:30,509][WARN ][o.e.d.c.ParseField ] Deprecated field [all_fields] used, replaced by [Set [fields] to `*` instead]
[2023-05-22T05:46:30,515][WARN ][o.e.d.c.ParseField ] Deprecated field [inline] used, expected [source] instead
[2023-05-22T05:46:30,520][WARN ][o.e.d.c.ParseField ] Deprecated field [inline] used, expected [source] instead