RMAN刪除歸檔日誌不釋放問題
今天同事問到一個問題，他那邊的一套Oracle 11g數據庫使用RMAN沒辦法刪除舊的歸檔，導致磁盤使用率很高。
[email protected]:[/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 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;查看日誌也沒有顯示舊歸檔日誌的記錄
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檢查也沒有查到舊歸檔日誌記錄
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$archived_log視圖也沒有舊歸檔日誌記錄
於是百度找到一篇文章http://3y.uu456.com/bp_3i90z4529l10ttd0odyk_1.html 大體意思是MAN刪除歸檔日誌的依據是controlfile中記錄的歸檔日誌，而不是你磁盤上實際存在的歸檔日誌
，如果你的歸檔日誌已經不在controlfile中就無法被RMAN識別到，也就無法被刪除。而致於歸檔信息何時在控制文件中被覆蓋，這由一個參數control_file_record_keep_time來控制。
查看數據庫中的參數是默認的7天
[email protected]> show parameter CONTROL_FILE_RECORD_KEEP_TIME
NAME TYPE VALUE
------------------------------------ -------------------------------- ------------------------------
control_file_record_keep_time integer 7
難道是在控制文件中歸檔日誌的記錄條數只能保留7天的麽？於是到MOS去找相關文檔找到一篇Why Are Controlfile
Entries For Archived Logs Not Overwritten After
CONTROL_FILE_RECORD_KEEP_TIME? (文檔 ID
1056085.1)，文檔介紹CONTROL_FILE_RECORD_KEEP_TIME參數並不是強制在控制文件中保留多少天的歸檔日誌條目，而是由V$CONTROLFILE_RECORD_SECTION視圖中的ARCHIVED
LOG條目去控制的，當RECORDS_TOTAL=RECORDS_USED時舊的歸檔日誌就會被覆蓋掉。
於是查數據庫中的V$CONTROLFILE_RECORD_SECTION視圖，看到ARCHIVED LOG行的records_total=224意味著控制文件中只能保留224條歸檔日誌文件信息。
[email protected]> select * from v$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
查詢v$archived_log視圖，總數為224條
[email protected]> select count(*) from v$archived_log;
COUNT(*)
----------
224
這時應該可以推斷出由於控制文件中只能保留224條歸檔日誌數據，所以以前的歸檔信息已經被控制文件刷出，RMAN無法識別到這些歸檔文件，所以就無法刪除這些歸檔日誌。
那麽現在如果使用RMAN刪除這些舊的歸檔日誌呢？我想到使用catalog start with 命令重新註冊這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
......
舊的歸檔日誌文件已經註冊到控制文件中了，再使用RMAN進行刪除就可以了
delete archivelog until logseq 1007;
再次查詢v$controlfile_record_section視圖，records_total也被“撐”大了
[email protected]> select * from v$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
至此問題結束。
RMAN刪除歸檔日誌不釋放問題