日期：20130605 10：00

?環境：ORACLE 11.2.0.3 RAC,雙節點，

REDHAT 5.8 +DS: DELL 3600I

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查詢過去24小時的日志切換之間的平均，最大，最小次數：平均時間在5分鐘以下，可能建議要求增加日志文件的大小：

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WITHlog_history AS

?????? (SELECTthread#, first_time,

?????????????? LAG(first_time)OVER (ORDERBYthread#, sequence#)

????????????????? last_first_time,

?????????????? (first_time

??????????????? - LAG(first_time)OVER (ORDERBYthread#, sequence#))

??????????????????? * 24* 60?? last_log_time_minutes,

?????????????? LAG(thread#)OVER (ORDERBYthread#, sequence#)

?????????????????? last_thread#

??????? FROMv$log_history)

SELECTROUND(MIN(last_log_time_minutes),2) min_minutes,

?????? ROUND(MAX(last_log_time_minutes),2) max_minutes,

?????? ROUND(AVG(last_log_time_minutes),2) avg_minutes

FROM log_history

WHERE???? last_first_time ISNOTNULL

????? ANDlast_thread# = thread#

????? ANDfirst_time > SYSDATE - 1;

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查詢結果：

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?? ?? MIN_MINUTES?? MAX_MINUTES?? AVG_MINUTES

-------------------------------------------------------------------------------------------------

1?????? 0.03? ?????????????????? 160.22??????? ?????????????????? 2.03

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查詢日志

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SQL> showparameters thread;

NAME???????????????????????????????? TYPE??????? VALUE

----------------------------------------------- ------------------------------

parallel_threads_per_cpu???????????? integer???? 2

thread?????????????????????????????? integer???? 2

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在集群環境中，每個節點上的數據庫實例都需要自己的重做日志組。例如，如果集群數據庫擁有三個節點和實例，每個實例至少有兩個重做日志組，則整個集群至少 需要6個聯機重做日志組。一般而言，兩個日志組是最低限量，工程上可以給每個實例更多的組。一則提高效率，二則提高恢復性。但無論多少組，所有日志文件存 放于共享存儲介質上，并可以被其他實例訪問。

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服務器參數文件中的thread參數定義了節點一(rac1)實例的線程號為1，而節點而節點二（rac2)實例的線程號為2:

Initracdb1.ora

racdb1.instance_number=1

racdb2.instance_number=2

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查詢當前日志文件組及所屬實例：

selectgroup#,THREAD#,l.MEMBERS,BYTES fromv$log l

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?? ?? GROUP#??? THREAD#?? MEMBERS BYTES

1?????? 1?????? ?????????????????? 1?????? ???????? 2?????? 52428800

2?????? 2?????? ?????????????????? 1?????? ???????? 2?????? 52428800

3?????? 3?????? ?????????????????? 2?????? ???????? 2?????? 52428800

4?????? 4?????? ?????????????????? 2?????? ???????? 2?????? 52428800

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下面來給線程1的實例添加一個組，組號為5，采用ASM自動存儲方式，因此無需指定文件名和大小：
SQL>alter database add logfile thread 1 group 5? size 102400kb;

下面來給線程2的實例添加一個組，組號為6，采用ASM自動存儲方式，因此無需指定文件名和大小。
SQL>alter database add logfile thread 2 group 6 size 102400kb;

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在各個節點進行：切換當前日志到新的日志組
　　alter system switch logfile;
　　alter system switch logfile;

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selectgroup#,THREAD#,l.MEMBERS,BYTES,l.STATUS fromv$log l

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?? ?? GROUP#??? THREAD#?? MEMBERS BYTES??????? STATUS

1?????? ???????? 1?????? ???????? 1?????? 2?????? ???????? 52428800?? ACTIVE

2?????? ???????? 2?????? ???????? 1?????? 2?????? ???????? 52428800?? INACTIVE

3?????? ???????? 3?????? ???????? 2?????? 2?????? ???????? 52428800?? INACTIVE

4?????? ???????? 4?????? ???????? 2?????? 2?????? ???????? 52428800?? ACTIVE

5?????? ???????? 5?????? ???????? 1?????? 2?????? ???????? 104857600 CURRENT

6?????? ???????? 6?????? ???????? 2?????? 2?????? ???????? 104857600 CURRENT

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3、刪除舊的日志組

　　alter database drop logfile group 2;
　　alter database drop logfile group 3;

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下面步驟為添加兩個日志組，5，6到進程1，2，并修改其它日志組，把大小從50M 修改成100 M,

先切換日志從active到 inactive,再刪除日志組，后添加日志組。

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SQL> alterdatabase add logfile thread 1 group 5?size 100M;

alter database addlogfile thread 1 group 5? size 100M

ORA-00933: SQL 命令未正確結束

SQL> alter database add logfile thread 1 group 5 ;

Database altered

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SQL> alter database add logfile thread 2 group 6 ;

Database altered

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SQL> alter system switch logfile;

System altered

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SQL> alter database drop logfile group 2;

Database altered

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SQL> alter database add logfile thread 1 group 2 ;

Database altered

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SQL> alter database drop logfile group 3;

Database altered

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SQL> alter database add logfile thread 2 group 3 ;

Database altered

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SQL> alter system switch logfile;

System altered

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SQL> alter database drop logfile group 1;

Database altered

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SQL>? alterdatabase add logfile thread 1 group 1 ;

Database altered

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SQL> alter database drop logfile group 4;

Database altered

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SQL> alter database add logfile thread 2 group 4;

Database altered

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SQL>? altersystem switch logfile;

System altered

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以上添加的日志組，ORACLE RAC 會按照文件保存規則，自動生成兩個文件：

?? ??? GROUP#???? STATUS????? TYPE MEMBER??? IS_RECOVERY_DEST_FILE

1?????? 5???????????????? ONLINE????? +DATA/racdb/onlinelog/group_5.322.817383997????? NO

2?????? 5???????????????? ONLINE????? +RECOVERY/racdb/onlinelog/group_5.374.817383999?????? YES

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======================================================================

完成后：

?? ? GROUP# THREAD#???????? MEMBERS?????? BYTES?????? ???????? STATUS

--------------------------------------------------------------------------------------------

1?????? ???????? 1?????? ???????? 1?????? ???????? 2?????? ?????????????????? 104857600?????? CURRENT

2?????? ???????? 2?????? ???????? 1?????? ???????? 2?????? ?????????????????? 104857600?????? ACTIVE

3?????? ???????? 3?????? ???????? 2?????? ???????? 2?????? ?????????????????? 104857600?????? ACTIVE

4?????? ???????? 4?????? ???????? 2?????? ???????? 2?????? ?????????????????? 104857600?????? CURRENT

5?????? ???????? 5?????? ???????? 1?????? ???????? 2?????? ?????????????????? 104857600?????? ACTIVE

6?????? ???????? 6?????? ???????? 2?????? ???????? 2?????? ?????????????????? 104857600?????? ACTIVE

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備份一下控制文件：

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RMAN>? backup current controlfile

2> ;

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Starting backup at2013-06-06 11:29:26

using targetdatabase control file instead of recovery catalog

allocated channel:ORA_DISK_1

channelORA_DISK_1: SID=7254 instance=racdb1 device type=DISK

channelORA_DISK_1: starting full datafile backup set

channelORA_DISK_1: specifying datafile(s) in backup set

including currentcontrol file in backup set

channelORA_DISK_1: starting piece 1 at 2013-06-06 11:29:31

channelORA_DISK_1: finished piece 1 at 2013-06-06 11:29:38

piecehandle=+RECOVERY/racdb/backupset/2013_06_06/ncnnf0_tag20130606t112928_0.387.817385371tag=TAG20130606T112928 comment=NONE

channelORA_DISK_1: backup set complete, elapsed time: 00:00:07

Finished backup at2013-06-06 11:29:38

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Starting ControlFile Autobackup at 2013-06-06 11:29:38

piecehandle=+RECOVERY/racdb/autobackup/2013_06_06/n_817385379.390.817385381comment=NONE

Finished ControlFile Autobackup at 2013-06-06 11:29:46

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RMAN> listbackup of controlfile;

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后面跟蹤一天后的情況。

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參考URL:

http://netclassroom.blog.163.com/blog/static/13575134420118234357827/

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