ORA-38760: This database instance failed to turn on flashback database，ora-38760flashback

ORA-38760: This database instance failed to turn on flashback database，ora-38760flashback
ORA-38760: This database instance failed to turn on flashback database

問題背景:
       測試資料庫執行shutdown immediate，日誌裡面報錯，錯誤資訊為：ORA-19815: WARNING: db_recovery_file_dest_size of 4322230272 bytes is 99.77% used, and has 9814016 remaining bytes available.
       隨即我執行startup force mount將資料庫強制關閉並啟動到mount狀態，通過RMAN把曆史備份和歸檔資訊都刪除後啟動資料庫報錯ORA-38760.

問題現象：

SQL> startup mount;ORACLE instance started.Total System Global Area 2872786944 bytesFixed Size                  2256712 bytesVariable Size            2634023096 bytesDatabase Buffers          218103808 bytesRedo Buffers               18403328 bytesDatabase mounted.SQL> alter database open;alter database open*ERROR at line 1:ORA-38760: This database instance failed to turn on flashback database

問題分析：
    該錯誤通過查看Metalink 後得知是因為Flash back資訊不完整導致。

[oracle@db01 ~]$ oerr or 38760oerr: Unknown facility 'or'[oracle@db01 ~]$ oerr ora 3876038760, 00000, "This database instance failed to turn on flashback database"// *Cause: Database flashback is on but this instance failed to//         start generating flashback data. Look in alert log for more//         specific errors.// *Action: Correct the error or turn off database flashback.

解決辦法：

#1、關閉flash backup再open databaseSQL> alter database flashback off;SQL> alter database open;#2、另外一種辦法直接關閉資料庫後再啟動也是可以的SQL> startup force mount;ORACLE instance started.Total System Global Area 2872786944 bytesFixed Size                  2256712 bytesVariable Size            2634023096 bytesDatabase Buffers          218103808 bytesRedo Buffers               18403328 bytesDatabase mounted.SQL> alter database open;Database altered.SQL>

oracle開啟flashback功可以失敗，錯誤資訊：ORA-00439: 未啟用功可以: Flashback Database；

flashback database要求資料庫必須處于歸檔模式，且閃回之後必須使用resetlogs開啟資料庫
查看資料庫的歸檔模式及閃回是否啟用
SQL> select log_mode,open_mode,flashback_on from v$database;

LOG_MODE OPEN_MODE FLASHBACK_ON
------------ ---------- ------------------
ARCHIVELOG READ WRITE NO --FLASHBACK_ON為NO，則表示閃回特性尚未啟用