Expired vs Obsolete

miloluo

摘自：Backup and Recovery Advanced User's Guide

The term obsolete does not mean the same as expired.

A backup is obsolete when REPORT OBSOLETE or DELETE OBSOLETE determines, based on the user-defined retention policy, that it is not needed for recovery.
A backup is considered expired only when RMAN performs a crosscheck and cannot find the file.

In short, obsolete means "not needed," whereas expired means "not found."

原來一直沒分清，最后一句話把這個(gè)解釋得很精煉。。。