（628）The database is running in the ARCHIVELOG mode.It has three redo log groups with one member each.

One of the redo log groups has become corrupted.

You have issued the following command during the recovery of a damaged redo log file: ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 3;

Which action should you perform immediately after using this command?

A. You should perform a log switch

B. You should make a backup of the database

C. You should switch the database to the NONARCHIVELOG mode

D. You should shut down the database instance and perform a complete database recovery

答案：（B）

解析：

执行的命令是重新创建日志组3，而且没有产生归档，那么就出现了归档不连续的情况，如果这个时候数据库损坏，是无法做完全恢复的。

因此要做一次备份，但是备份的类型没有具体的要求，如果前面有增量备份，此时做一个增量备份就可以了，无需一定要做一个完全的数据库备份

ITPub博客

Oracle 11G OCP 1Z0-053 628