作者：david_zhang@sh 【转载时请以超链接形式标明文章】
链接：http://www.cnblogs.com/david-zhang-index/archive/2012/07/01/2572190.html
oracle数据库启动时，scn检查原则及解决办法：
| Condition on Star-Up | Oracle Behavior | DBA Action |
| CF checkpoint < Datafile checkpoint SCN | "Control file too old"error | Restore a newer control file |
| CF checkpoint > Datafile checkpoint SCN | Media recovery required | Most likely a datafile has been restored from backup Recovery is now required |
| CF checkpoint = Datafile checkpoint SCN | Start up normally | None |
| Database in mount mode,instance thread status = OPEN | Crash recovery required | None |
备注:cf=control file
