RMAN 刪除無效 過期備份

刪除無效備份（根據備份策略不需要的）：DELETE OBSOLETE;
刪除過期備份（實際已經不存，空有一條記錄）：DELETE EXPIRED;

文檔如下：
Crosschecks update outdated RMAN repository information about backups whose repository records do not match their physical status.    DELETE EXPIRED;
The RMAN DELETE command supports an OBSOLETE option, which deletes backups that are no longer needed to satisfy specified recoverability requirements. 

刪除無效備份前查看下無效的文件：REPORT OBSOLETE;
刪除過期備份前要使用CROSSCHECK BACKUP;對記錄做檢查和標記。

刪除無效備份則需要先明確下當前的備份策略：
show retention policy;

改成保留3天的數據。
configure RETENTION POLICY TO recovery window of 3 days;