解决Oracle RMAN删除归档日志不释放问题的方法

前言

当Oracle 归档日志满了后,将无法正常登入oracle,需要删除一部分归档日志才能正常登入ORACLE。

最近同事在工作中遇到一个问题,他那边的一套Oracle 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。

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

解决过程

于是在网上找到一篇文章,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。

总结

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