1 数据库不重启也会把一些启动信息打在日志上，让你怀疑这库是不是无厘头重启，最重要的是没有其他的相关日志，让你怀疑是不是不要干DBA这行了；

1.1禁止参数信息dump至Alert日志中

_log_segment_dump_parameter=FALSE

1.2禁止补丁信息dump至Alert日志中

_log_segment_dump_patch=FALSE

参见:12c Alert Log Appears To Show Unexpected Instance Restart (文档 ID 2049516.1)

2　ORA-600 [K2GTEGET: PDBID] AND ORA-600 [KPDBSWITCHPRERESTORE: TXN］

参见：

Bug 19942889 : ORA-600 [KPDBSWITCHPRERESTORE: TXN]

Bug 19971949 : ORA-600 [K2GTEGET: PDBID] AND ORA-600 [KPDBSWITCHPRERESTORE: TXN]

参见文档说明

ORA-00600: Internal Error Code,arguments: [k2gteget: Pdbid] & Arguments: [kpdbSwitchPreRestore: Txn] (文档 ID 2090473.1)

打补丁Oracle Database 12c Release 12.1.0.2.170117

3 12c的多路径ORA-600 [krr_process_read_error_2]

临时解决办法：ALTER SYSTEM SET "_use_single_log_writer"=TRUE SID='*' SCOPE=SPFILE;

Oracle 12c introduces a new default feature of using multiple LGWRs whichmay lead to DEADLOCK / Database Hang or ORA-742 "Log read detects lost write" or ORA-600 [kcrfrgv_nextlwn_scn] during instance OPEN or ORA-600 [krr_process_read_error_2] during Recovery on IBM AIX and potentially on HPUX Itanium 64bit.

参考：

ALERT: Bug 21915719 Database hang or may fail to OPEN in 12c IBM AIX or HPUX Itanium - ORA-742,DEADLOCK or ORA-600 [kcrfrgv_nextlwn_scn] ORA-600 [krr_process_read_error_2] (文档 ID 1957710.1)