RMAN无法删除归档日志

今天同事问到一个问题，他那边的一套11g数据库使用RMAN没办法删除旧的归档，导致磁盘使用率很高。要来ip登录上去一看确实是，最旧的归档日志是16年5月的。

oracle@ps251n2s:[/opt/oracle/archive/db] ls -ltr |more
total 3059881082
-rw-r-----   1 oracle     oinstall   725320704 May 20  2016 1_1_91233774.dbf
-rw-rw----   1 oracle     oinstall   1756937216 Jun  7  2016 1_2_91233774.dbf
-rw-rw----   1 oracle     oinstall   1756731392 Jun 21  2016 1_3_91233774.dbf
-rw-rw----   1 oracle     oinstall   1758001152 Jul  3  2016 1_4_91233774.dbf
-rw-rw----   1 oracle     oinstall   1756729344 Jul 15  2016 1_5_91233774.dbf
-rw-rw----   1 oracle     oinstall   1765750784 Jul 26 22:00 1_6_91233774.dbf
-rw-rw----   1 oracle     oinstall   1760346112 Aug  6 14:04 1_7_91233774.dbf
......

使用RMAN list archivelog all;查看日志也没有显示旧归档日志的记录

RMAN> list archivelog all;

using target database control file instead of recovery catalog
List of Archived Log Copies for database with db_unique_name DBS
=====================================================================

Key     Thrd Seq     S Low Time
------- ---- ------- - ---------
1206    1    1206    A 14-JAN-17
Name: /opt/oracle/archive/db/1_1206_91233774.dbf

1207    1    1207    A 14-JAN-17
Name: /opt/oracle/archive/db/1_1207_91233774.dbf

1208    1    1208    A 14-JAN-17
Name: /opt/oracle/archive/db/1_1208_91233774.dbf
......

使用crosscheck检查也没有查到旧归档日志记录

RMAN> crosscheck archivelog all;

using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=16 device type=DISK
validation succeeded for archived log
archived log file name=/opt/oracle/archive/db/1_1206_91233774.dbf RECID=1206 STAMP=933244655
validation succeeded for archived log
archived log file name=/opt/oracle/archive/db/1_1207_91233774.dbf RECID=1207 STAMP=933249510
validation succeeded for archived log
archived log file name=/opt/oracle/archive/db/1_1208_91233774.dbf RECID=1208 STAMP=933254500
validation succeeded for archived log
archived log file name=/opt/oracle/archive/db/1_1209_91233774.dbf RECID=1209 STAMP=933259445
validation succeeded for archived log

查看v$archived_log视图也没有旧归档日志记录

于是百度找到一篇文章http://3y.uu456.com/bp_3i90z4529l10ttd0odyk_1.html 大体意思是MAN删除归档日志的依据是controlfile中记录的归档日志，而不是你磁盘上实际存在的归档日志
，如果你的归档日志已经不在controlfile中就无法被RMAN识别到，也就无法被删除。而致于归档信息何时在控制文件中被覆盖，这由一个参数control_file_record_keep_time来控制。
查看数据库中的参数是默认的7天

SYS@db> show parameter CONTROL_FILE_RECORD_KEEP_TIME

NAME                                 TYPE                             VALUE
------------------------------------ -------------------------------- ------------------------------
control_file_record_keep_time        integer                          7

难道是在控制文件中归档日志的记录条数只能保留7天的么？于是到MOS去找相关文档找到一篇Why Are Controlfile Entries For Archived Logs Not Overwritten After CONTROL_FILE_RECORD_KEEP_TIME? (文档 ID 1056085.1)，文档介绍CONTROL_FILE_RECORD_KEEP_TIME参数并不是强制在控制文件中保留多少天的归档日志条目，而是由V$CONTROLFILE_RECORD_SECTION视图中的ARCHIVED LOG条目去控制的，当RECORDS_TOTAL=RECORDS_USED时旧的归档日志就会被覆盖掉。
于是查数据库中的V$CONTROLFILE_RECORD_SECTION视图，看到ARCHIVED LOG行的records_total=224意味着控制文件中只能保留224条归档日志文件信息。

SYS@dbs> select * from v$controlfile_record_section where type='ARCHIVED LOG';

TYPE                         RECORD_SIZE RECORDS_TOTAL RECORDS_USED FIRST_INDEX LAST_INDEX LAST_RECID
---------------------------- ----------- ------------- ------------ ----------- ---------- ----------
ARCHIVED LOG                         584           224          224          88         87       1235

查询v$archived_log视图，总数为224条

SYS@dbs> select count(*) from v$archived_log;

COUNT(*)
----------
224

这时应该可以推断出由于控制文件中只能保留224条归档日志数据，所以以前的归档信息已经被控制文件刷出，RMAN无法识别到这些归档文件，所以就无法删除这些归档日志。
那么现在如果使用RMAN删除这些旧的归档日志呢？我想到使用catalog start with 命令重新注册这些文件到控制文件中

RMAN> catalog start with '/opt/oracle/archive/db';
......
File Name: /opt/oracle/archive/db/1_1005_91233774.dbf
File Name: /opt/oracle/archive/db/1_1006_91233774.dbf
File Name: /opt/oracle/archive/db/1_1007_91233774.dbf

Do you really want to catalog the above files (enter YES or NO)? yes
cataloging files...
cataloging done
......
RMAN> list archivelog all;
.....
1236    1    301     A 22-OCT-16
Name: /opt/oracle/archive/db/1_301_91233774.dbf

1237    1    302     A 22-OCT-16
Name: /opt/oracle/archive/db/1_302_91233774.dbf
......

旧的归档日志文件已经注册到控制文件中了，再使用RMAN进行删除就可以了

delete archivelog until logseq 1007;

再次查询v$controlfile_record_section视图，records_total也被“撑”大了

SYS@db> select * from v$controlfile_record_section where type='ARCHIVED LOG';

TYPE                         RECORD_SIZE RECORDS_TOTAL RECORDS_USED FIRST_INDEX LAST_INDEX LAST_RECID
---------------------------- ----------- ------------- ------------ ----------- ---------- ----------
ARCHIVED LOG                         584           896          742         807        652       1800

至此问题结束。