resetlogs 打開數據庫時新生成日誌位置問題
若系統中缺少聯機日誌，以resetlogs方式重建控制文件，那麼當我們以alter database open resetlogs方式打開數據庫時，新生成的聯機日誌會位於何處？
一：下面分別討論幾種情況
1 如果在重建控制文件語句中未指定日誌條目，未指定omf參數，那麼resetlogs 打開數據庫時，自動創建的日誌位於何處
2 如果在重建控制文件語句中未指定日誌條目，僅指定了omf參數db_create_file_dest， 那麼resetlogs 打開數據庫時，自動創建的日誌位於何處
3 如果在重建控制文件語句中指定了日誌條目，指定了omf參數，那麼resetlogs 打開數據庫事，自動創建的日誌位於何處
4 如果在重建控制文件語句中未指定日誌條目，指定了omf參數db_create_file_dest和 db_create_online_log_dest_n 那麼resetlogs 打開數據庫時，自動創建的日誌位於何處
二：實驗
實驗1 重建控制文件語句未指定日誌條目，未指定omf參數，那麼resetlogs打開數據庫後日志位置
1 實驗前提
重建控制文件中不指定日誌條目語句如下
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "ZBCRM" RESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
DATAFILE
'/oracle/CRM/ZBCRM/system01.dbf',
'/oracle/CRM/ZBCRM/sysaux01.dbf',
'/oracle/CRM/ZBCRM/undotbs01.dbf',
'/oracle/CRM/ZBCRM/users01.dbf',
'/oracle/CRM/ZBCRM/sysaux02.dbf'
CHARACTER SET ZHS16GBK
;
參數文件中未指定omf參數
NAME VALUE
---------------------------------------- --------------------------------------------------
db_create_file_dest
db_create_online_log_dest_1
db_create_online_log_dest_2
db_create_online_log_dest_3
db_create_online_log_dest_4
db_create_online_log_dest_5
db_recovery_file_dest
db_recovery_file_dest_size 0
2 過程如下：
SQL> @/oracle/control1.sql
ORACLE instance started.
Total System Global Area 1152450560 bytes
Fixed Size 2225832 bytes
Variable Size 704645464 bytes
Database Buffers 436207616 bytes
Redo Buffers 9371648 bytes
Control file created.
SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open
SQL> alter database open resetlogs;
Database altered.
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
READ WRITE
SQL> col member for a50
SQL> select group#,member from v$logfile;
GROUP# MEMBER
---------- --------------------------------------------------
2 /oracle/app/db1/dbs/log2ZBCRM.dbf
1 /oracle/app/db1/dbs/log1ZBCRM.dbf
結果：當控制文件重建語句中未指定日誌條目，也未設置omf參數，那麼resetlogs 打開數據庫後新創建的日誌文件位於dbs目錄下。
實驗2 重建控制文件語句中未指定了日誌位置，指定omf參數，那麼resetlogs打開數據庫後日志位置
1 實驗前提
重建控制文件語句如下
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "ZBCRM" RESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
DATAFILE
'/oracle/CRM/ZBCRM/system01.dbf',
'/oracle/CRM/ZBCRM/sysaux01.dbf',
'/oracle/CRM/ZBCRM/undotbs01.dbf',
'/oracle/CRM/ZBCRM/users01.dbf',
'/oracle/CRM/ZBCRM/sysaux02.dbf'
CHARACTER SET ZHS16GBK
;
參數文件中指定omf參數
NAME VALUE
---------------------------------------- ----------------------------------------
db_create_file_dest /oracle/CRM/ZBCRM/
db_create_online_log_dest_1
db_create_online_log_dest_2
db_create_online_log_dest_3
db_create_online_log_dest_4
db_create_online_log_dest_5
db_recovery_file_dest
db_recovery_file_dest_size 0
2 實驗過程如下：
[oracle@oracle ~]$ cat control1.sql
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "ZBCRM" RESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
DATAFILE
'/oracle/CRM/ZBCRM/system01.dbf',
'/oracle/CRM/ZBCRM/sysaux01.dbf',
'/oracle/CRM/ZBCRM/undotbs01.dbf',
'/oracle/CRM/ZBCRM/users01.dbf',
'/oracle/CRM/ZBCRM/sysaux02.dbf'
CHARACTER SET ZHS16GBK
;
[oracle@oracle ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Fri Jul 26 16:33:49 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to an idle instance.
SQL> @/oracle/control1.sql
ORACLE instance started.
Total System Global Area 1152450560 bytes
Fixed Size 2225832 bytes
Variable Size 704645464 bytes
Database Buffers 436207616 bytes
Redo Buffers 9371648 bytes
Control file created.
SQL> alter database open resetlogs;
Database altered.
SQL> col member for a60
SQL> /
GROUP# MEMBER
---------- ------------------------------------------------------------
2 /oracle/CRM/ZBCRM/ZBCRM/onlinelog/o1_mf_2_8z4f4kon_.log
1 /oracle/CRM/ZBCRM/ZBCRM/onlinelog/o1_mf_1_8z4f4gcl_.log
結果：當重建控制文件語句中爲指定日誌條目，僅指定omf參數db_create_file_dest時，resetlogs打開數據庫後，日誌位於db_create_file_dest指定的目錄。
實驗3 重建控制文件語句指定日誌條目，指定omf參數，那麼resetlogs打開數據庫後日志位置
1 實驗前提
重建控制文件中指定日誌條目語句如下
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "ZBCRM" RESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
LOGFILE
GROUP 1 '/oracle/CRM/ZBCRM/redo01.log' SIZE 200M BLOCKSIZE 512,
GROUP 2 '/oracle/CRM/ZBCRM/redo02.log' SIZE 200M BLOCKSIZE 512,
GROUP 3 '/oracle/CRM/ZBCRM/redo03.log' SIZE 200M BLOCKSIZE 512
-- STANDBY LOGFILE
DATAFILE
'/oracle/CRM/ZBCRM/system01.dbf',
'/oracle/CRM/ZBCRM/sysaux01.dbf',
'/oracle/CRM/ZBCRM/undotbs01.dbf',
'/oracle/CRM/ZBCRM/users01.dbf',
'/oracle/CRM/ZBCRM/sysaux02.dbf'
CHARACTER SET ZHS16GBK
;
2 omf 參數如下：
NAME VALUE
-------------------------------------------------- ------------------------------------------------------------
db_create_file_dest /oracle/CRM/ZBCRM/
db_create_online_log_dest_1 /oracle/CRM/ZBCRM/log1
db_create_online_log_dest_2 /oracle/CRM/ZBCRM/log2
db_create_online_log_dest_3
db_create_online_log_dest_4
db_create_online_log_dest_5
db_recovery_file_dest
db_recovery_file_dest_size 0
3 實驗過程如下：
[oracle@oracle ~]$ cat control2.sql
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "ZBCRM" RESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
LOGFILE
GROUP 1 '/oracle/CRM/ZBCRM/redo01.log' SIZE 200M BLOCKSIZE 512,
GROUP 2 '/oracle/CRM/ZBCRM/redo02.log' SIZE 200M BLOCKSIZE 512,
GROUP 3 '/oracle/CRM/ZBCRM/redo03.log' SIZE 200M BLOCKSIZE 512
-- STANDBY LOGFILE
DATAFILE
'/oracle/CRM/ZBCRM/system01.dbf',
'/oracle/CRM/ZBCRM/sysaux01.dbf',
'/oracle/CRM/ZBCRM/undotbs01.dbf',
'/oracle/CRM/ZBCRM/users01.dbf',
'/oracle/CRM/ZBCRM/sysaux02.dbf'
CHARACTER SET ZHS16GBK
;
[oracle@oracle ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Fri Jul 26 16:52:26 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to an idle instance.
SQL> @/oracle/control2.sql
ORACLE instance started.
Total System Global Area 1152450560 bytes
Fixed Size 2225832 bytes
Variable Size 704645464 bytes
Database Buffers 436207616 bytes
Redo Buffers 9371648 bytes
Control file created.
SQL> alter database open resetlogs;
Database altered.
SQL> col member for a50
SQL> select group#,member from v$logfile;
GROUP# MEMBER
---------- --------------------------------------------------
3 /oracle/CRM/ZBCRM/redo03.log
2 /oracle/CRM/ZBCRM/redo02.log
1 /oracle/CRM/ZBCRM/redo01.log
結果：當重建控制文件語句中指定日誌條目，又指定了omf參數，那麼新生成的日誌文件位置以控制文件爲準。
實驗4 重建控制文件語句中未指定了日誌位置，指定omf參數db_create_file_dest和 db_create_online_log_dest_n，那麼resetlogs打開數據庫後日志位置
1 實驗前提
重建控制文件中指定日誌條目語句如下
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "ZBCRM" RESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
LOGFILE
GROUP 1 '/oracle/CRM/ZBCRM/redo01.log' SIZE 200M BLOCKSIZE 512,
GROUP 2 '/oracle/CRM/ZBCRM/redo02.log' SIZE 200M BLOCKSIZE 512,
GROUP 3 '/oracle/CRM/ZBCRM/redo03.log' SIZE 200M BLOCKSIZE 512
-- STANDBY LOGFILE
DATAFILE
'/oracle/CRM/ZBCRM/system01.dbf',
'/oracle/CRM/ZBCRM/sysaux01.dbf',
'/oracle/CRM/ZBCRM/undotbs01.dbf',
'/oracle/CRM/ZBCRM/users01.dbf',
'/oracle/CRM/ZBCRM/sysaux02.dbf'
CHARACTER SET ZHS16GBK
;
2 omf 參數如下：
NAME VALUE
-------------------------------------------------- ------------------------------------------------------------
db_create_file_dest /oracle/CRM/ZBCRM/
db_create_online_log_dest_1 /oracle/CRM/ZBCRM/log1
db_create_online_log_dest_2 /oracle/CRM/ZBCRM/log2
db_create_online_log_dest_3
db_create_online_log_dest_4
db_create_online_log_dest_5
db_recovery_file_dest
db_recovery_file_dest_size 0
3 實驗過程如下：
[oracle@oracle ~]$ cat control1.sql
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE DATABASE "ZBCRM" RESETLOGS ARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
DATAFILE
'/oracle/CRM/ZBCRM/system01.dbf',
'/oracle/CRM/ZBCRM/sysaux01.dbf',
'/oracle/CRM/ZBCRM/undotbs01.dbf',
'/oracle/CRM/ZBCRM/users01.dbf',
'/oracle/CRM/ZBCRM/sysaux02.dbf'
CHARACTER SET ZHS16GBK
;
[oracle@oracle ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Fri Jul 26 17:01:24 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to an idle instance.
SQL> @/oracle/control1.sql
ORACLE instance started.
Total System Global Area 1152450560 bytes
Fixed Size 2225832 bytes
Variable Size 704645464 bytes
Database Buffers 436207616 bytes
Redo Buffers 9371648 bytes
Control file created.
SQL> alter database open resetlogs;
Database altered.
SQL> col member for a60
SQL> select group#,member from v$logfile;
GROUP# MEMBER
---------- ------------------------------------------------------------
2 /oracle/CRM/ZBCRM/log1/ZBCRM/onlinelog/o1_mf_2_8z4grccs_.log
2 /oracle/CRM/ZBCRM/log2/ZBCRM/onlinelog/o1_mf_2_8z4grd0x_.log
1 /oracle/CRM/ZBCRM/log1/ZBCRM/onlinelog/o1_mf_1_8z4gr4yz_.log
1 /oracle/CRM/ZBCRM/log2/ZBCRM/onlinelog/o1_mf_1_8z4gr5p0_.log
結果：ofm參數中優先級db_create_online_log_dest_n高於db_create_file_dest
總結：通過以上實驗不難看出，當resetlogs打開數據庫時，生成新的日誌文件位置由以下因素決定：
先以控制文件中記錄的日誌文件位置爲準.如果控制文件中沒日誌位置信息，則會查omf參數，優先級爲，先db_create_online_log_dest_n後db_create_file_dest。
如果未指定omf參數則生成日誌文件的默認位置爲：比如linux 就是dbs下。