I faced with that error on r12.1.3 EBS system. My db version is 11.2&2 node RAC system.
My first node is goes down by below errors:
opiodr aborting process unknown ospid (11075852) as a result of ORA-28 LMON (ospid: 63767522) detects hung instances during IMR reconfiguration LMON (ospid: 63767522) tries to kill the instance 2. Please check instance 2’s alert log and LMON trace file for more details. Tue Mar 19 10:58:36 2020 USER (ospid: 32900426): terminating the instance due to error 481 Tue Mar 19 10:58:36 2020 Errors in file /oracle11g/PROD00/db/diag/rdbms/PROD00/PROD001/trace/PROD001_lmon_63767522.trc: ORA-29702: error occurred in Cluster Group Service operation System state dump is made for local instance System State dumped to trace file /oracle11g/PROD00/db/diag/rdbms/PROD00/PROD001/trace/PROD001_diag_9373174.trc Instance terminated by USER, pid = 32900426
From PROD001_lmon_63767522.trc file:
*** 2020-03-19 10:55:00.531 * DRM RCFG called (swin 1) CGS recovery timeout = 85 sec Begin DRM(5108) (swin 1) *** 2020-03-19 10:57:11.567 Name Service frozen .. ... kjxgmpoll: terminate the CGS reconfig. Error: Cluster Group Service reconfiguration takes too long <<< here is error LMON caught an error 29702 in the main loop error 29702 detected in background process <<< here is error code ORA-29702: error occurred in Cluster Group Service operation
I see many drm quiesce hang messages in the lmon.trc files
find . -name "*lmon*.trc" |xargs grep -i "quiesce hang" ./oracle/PROD001_lmon_63767522.trc:* Request pseudo reconfig due to drm quiesce hang ./oracle/PROD001_lmon_63767522.trc:* Request pseudo reconfig due to drm quiesce hang ./oracle/PROD002_lmon_14221454.trc:* Request pseudo reconfig due to drm quiesce hang ./oracle/PROD002_lmon_14221454.trc:* Request pseudo reconfig due to drm quiesce hang ./oracle/PROD002_lmon_14221454.trc:* Request pseudo reconfig due to drm quiesce hang ./oracle/PROD002_lmon_14221454.trc:* Request pseudo reconfig due to drm quiesce hang ./oracle/PROD002_lmon_14221454.trc:* Request pseudo reconfig due to drm quiesce hang
Based on these, The issue does appear to be an occurrence of bug : 12879027 LMON gets stuck in DRM quiescence causing intermittent pseudo reconfiguration
To get the fix for the bug, please install the 11.2.0.3 patchset into the rdbms $ORACLE_HOME and then , apply on top, the 11.2.0.3.3 PSU, or higher/later PSUs
More details can be found at MOS note: Bug 12879027 – LMON gets stuck in DRM quiesce causing intermittent pseudo reconfiguration [ID 12879027.8]