参见：Doc ID 2628748.1
https://support.oracle.com/epmos/faces/DocumentDisplay?_afrLoop=22951512720000&id=2628748.1&_adf.ctrl-state=1czg8zjl2h_53
数据库版本：Oracle RAC 18.3
1. 故障现象（SYMPTOMS）
在 Grid Infrastructure (GI) 环境中的某些节点中，以下消息每 30 分钟重复报告一次。（并非所有节点）
GI alert.log indicates (alert.log inside <ORACLE_BASE>/diag/crs/<node>/crs/trace location):
2021-09-12 11:17:27.278 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
2021-09-12 11:47:28.949 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
2021-09-12 12:17:30.589 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
2021-09-12 12:47:32.243 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
2021-09-12 13:17:33.888 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
2021-09-12 13:47:35.588 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
2021-09-12 14:17:37.213 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
2021-09-12 14:47:38.832 [OCTSSD(14975)]CRS-2412: The Cluster Time Synchronization Service detects that the local time is significantly different from the mean cluster time. Details in /u01/app/grid/diag/crs/dbcenter2/crs/trace/octssd.trc.
octssd.trc 显示从主节点发送的异常微秒。
octssd.trc (octssd.log inside ＜ORACLE_BASE＞/diag/crs/<node>/crs/trace location):
2021-09-12 11:20:47.481 : CTSS:696968960: sclsctss_ivsr2: default pid file not found
2021-09-12 11:20:47.481 : CTSS:696968960: sclsctss_ivsr1: default config file found
2021-09-12 11:20:47.481 : CTSS:696968960: sclsctss_gvss5: Chrony active, forcing observer mode
2021-09-12 11:20:47.481 : CTSS:696968960: ctss_check_vendor_sw: Vendor time sync software is detected. status [2].
2021-09-12 11:20:47.481 : CTSS:696968960: ctsselect_msm: CTSS mode is [0xe6]
2021-09-12 11:20:47.481 : CTSS:696968960: ctssslave_swm1_2: Ready to initiate new time sync process.
2021-09-12 11:20:47.482 : CTSS:696968960: ctssslave_swm2_1: Waiting for time sync message from master. sync_state[2].
2021-09-12 11:20:47.485 : CTSS:701171456: ctssslave_msg_handler4_1: Waiting for slave_sync_with_master to finish sync process. sync_state[3].
2021-09-12 11:20:47.485 : CTSS:696968960: ctssslave_swm2_3: Received time sync message from master.
2021-09-12 11:20:47.485 : CTSS:696968960: ctssslave_swm: The magnitude [11017094] of the offset [-11017094 usec] is detected to be too larger.
2021-09-12 11:20:47.485 : CTSS:696968960: ctssslave_swm17: LT [1631416847sec 485390usec], MT [1631416858sec 140548510296788usec], Delta [3565usec]
2021-09-12 11:20:47.485 : CTSS:696968960: ctssslave_swm19: The offset is [-11017094 usec] and sync interval set to [5]
2021-09-12 11:20:47.485 : CTSS:696968960: ctsselect_msm: Sync interval returned in [5]
2021-09-12 11:20:47.485 : CTSS:701171456: ctssslave_msg_handler4_3: slave_sync_with_master finished sync process. Exiting clsctssslave_msg_handler
2. 变化（CHANGES）
3. 故障原因（CAUSE）
该问题在内部/未发布的错误 30525849 中进行了分析和讨论，该错误稍后作为错误 29529973 的副本关闭。
4. 解决方案（SOLUTION）
错误 29529973 已在 20.1 中修复。 应用临时补丁 29529973（如果适用于您的平台和 Oracle 版本）。 如果您的版本不存在补丁，请联系 Oracle 支持以获得反向移植请求。
5. 总结（SUMMARY）
~]$ crsctl check ctss
CRS-4700: The Cluster Time Synchronization Service is in Observer mode.
~]# chronyc sourcestats
210 Number of sources = 2
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
47.13.xxx.xxx.in-addr.ar> 12 8 710 +0.205 0.295 +71us 49us
88.13.xxx.xxx.in-addr.ar> 6 4 85m -0.033 0.138 -42us 62us