12.2:[INS-35178]The Automatic Memory Management Option Is Not Allowed During RunInstaller or Using DBCA If Physical Memory Is Greater Than 4G. (文档 ID 2244817.1)
在12.2之前版本中也会出现当主机内存超过4G时,会出现告警提示不建议使用AMM。但是从12.2开始,当主机内存大于4G就直接报错无法继续安装数据库了。对此Oracle解释了具体原因:Because database creation fails some times and in some cases database wont be functional after some times .大概意思就是如果数据库创建失败几次后,可能会出现数据库创建后无法正常运行。