第二次备份，之前备份过的日志还出现在自动备份的列表中。但是，在第二次备份的时候，已经备份过两次（deletion policy）的日志并没有自动删除。
SQL> select count(*) from v$archived_log where archived='YES' and deleted='NO';
COUNT(*)
----------
17
归档日志还在fast recovery area中。
[oracle@Databaseintrawebpro fast_recovery_area]$ du -h
19M ./XXXXDB/autobackup/2015_09_21
9.4M ./XXXXDB/autobackup/2015_09_17
29M ./XXXXDB/autobackup
151M ./XXXXDB/onlinelog
6.0G ./XXXXDB/backupset/2015_09_21
108K ./XXXXDB/backupset/2015_09_17
6.0G ./XXXXDB/backupset
125M ./XXXXDB/archivelog/2015_09_19
27M ./XXXXDB/archivelog/2015_09_21
4.0K ./XXXXDB/archivelog/2015_09_15
127M ./XXXXDB/archivelog/2015_09_18
121M ./XXXXDB/archivelog/2015_09_20
4.0K ./XXXXDB/archivelog/2015_09_16
32M ./XXXXDB/archivelog/2015_09_17
431M ./XXXXDB/archivelog
9.4M ./XXXXDB/controlfile
6.6G ./XXXXDB
6.6G .
此时，归档日志和备份次数，在v$archived_log中可以方便的找出来。
SQL> alter system switch logfile;
System altered
SQL> select count(*) from v$archived_log where archived='YES' and deleted='NO';
COUNT(*)
----------
18
--注意这些已经备份过两次的recid编号
SQL> select recid, sequence#, archived, deleted, backup_count from v$archived_log where backup_count>1;
RECID SEQUENCE# ARCHIVED DELETED BACKUP_COUNT
---------- ---------- -------- ------- ------------
12 100 YES NO 2
13 101 YES NO 2
14 102 YES NO 2
15 103 YES NO 2
16 104 YES NO 2
17 105 YES NO 2
18 106 YES NO 2
19 107 YES NO 2
20 108 YES NO 2
21 109 YES NO 2
22 110 YES NO 2
23 111 YES NO 2
24 112 YES NO 2
25 113 YES NO 2
26 114 YES NO 2
15 rows selected
进行第三次备份。
RMAN> backup database plus archivelog;
Starting backup at 21-SEP-15
current log archived
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=498 device type=DISK
skipping archived logs of thread 1 from sequence 100 to 114; already backed up
channel ORA_DISK_1: starting archived log backup set
channel ORA_DISK_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=115 RECID=27 STAMP=890990391
input archived log thread=1 sequence=116 RECID=28 STAMP=890990481
input archived log thread=1 sequence=117 RECID=29 STAMP=890990667
input archived log thread=1 sequence=118 RECID=30 STAMP=890993128
channel ORA_DISK_1: starting piece 1 at 21-SEP-15
channel ORA_DISK_1: finished piece 1 at 21-SEP-15
piece
（篇幅原因，有省略…….）
Finished Control File and SPFILE Autobackup at 21-SEP-15