关于数据库备份及归档日志删除的步骤.这里称的备份指数据库的热备，即在数据库实例运行过程中通过RMAN工具对数据库做的备份，用以在数据库实例产生问题时用于数据库的恢复-Step on the database backup and archive logs deleted here called hot standby database backup means, namely through RMAN tool to make backup database during the database instance is running, for instance when the database is used to recover the database problems