数据库报错
数据库启动报ORA-00283和ORA-19821错

SQL> recover database;
ORA-00283: recovery session canceled due to errors
ORA-19821: an intentionally corrupt log file was found
SQL> recover datafile 1;
ORA-00283: recovery session canceled due to errors
ORA-19821: an intentionally corrupt log file was found

Thu May 03 12:06:51 2018
Recovery of Online Redo Log: Thread 1 Group 1 Seq 1 Reading mem 0
  Mem# 0: D:\APP\SOHTDB\ORADATA\xifenfei\REDO01.LOG
Media Recovery failed with error 19821
Errors in file d:\app\sohtdb\diag\rdbms\xifenfei\xifenfei\trace\xifenfei_pr00_660.trc:
ORA-00283: recovery session canceled due to errors
ORA-19821: an intentionally corrupt log file was found
Slave exiting with ORA-283 exception
Errors in file d:\app\sohtdb\diag\rdbms\xifenfei\xifenfei\trace\xifenfei_pr00_660.trc:
ORA-00283: recovery session canceled due to errors
ORA-19821: an intentionally corrupt log file was found
ORA-283 signalled during: ALTER DATABASE RECOVER  database  ...

ORA-19821报错原因
这个错误相对比较少见，查询mos，由于设置了_disable_logging = TRUE导致该问题

检查alert日志,_disable_logging参数确实被认为设置为true了.

解决方法
根据官方的描述,这样的情况无法常规恢复,但是我们知道设置这个参数是为了不产生日志,因此出现这种情况,只能通过隐含参数,禁止数据库进行实例恢复,强制打开数据库.在这样的过程中非常容易遭遇类似ORA-600 2662的错误.

设置这个参数是为了不产生日志，当数据库非干净关闭(主机断电，数据库crash，shutdown abort等）,就非常可能导致数据库无法正常启动.***千不可万不能在生产环境中设置_disable_logging = TRUE***
参考文档:Ora-19821 during the recovery (Doc ID 1217143.1)
Init.ora Parameter “_DISABLE_LOGGING” [Hidden] Reference Note (Doc ID 29552.1)