困擾許久的dataguard問題：error 12514 received logging on to the standby

搭建dataguard環境，主庫的歸檔日誌就是傳送不到備庫上

用select dest_name,error from v$archive_dest;

總是報錯：

ORA-12154: TNS:could not resolve the connect identifier specified

並且在主庫的alert日誌中有如下錯誤信息：

error 12514 received logging on to the standby

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由於最近幾個月搭建dataguard環境特別多，總會遇到這個問題，但我仔細檢查過配置，tnsnames.ora，log_archive_dest_2等信息都是正確的。

但是，歸檔日誌就是傳送不過去。之前遇到這種類似情況（太多了，記不清了），有使用過alter system set log_archive_dest_state_2=defer;

然後switch logfile，接着再改成enable:alter system set log_archive_dest_state_2=enable;解決過相關問題，但今天就是不行。

以前遇到這樣的情況，只好重啓數據庫，立馬就可以將歸檔日誌傳輸過去。但今天由於主庫已經上生產，不能隨便重啓，導致我也無計可施了。

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試着在metalink上搜了下（最近好幾個月都很懶，不思進取，就想着天上掉餡餅），發現瞭如下一篇文章，算是對這個問題有深入的瞭解了：

歸檔進程在數據庫啓動後，只會在初始化過程中讀取一次tnsnames.ora的信息，以後tnsnames.ora發生變化等情況，arch進程並不知曉。

這也就會導致當實例中log_archive_dest_2參數發生變化，arch識別不出相關tns別名，進而導致報錯ora-12154

文章中提供的解決辦法有：

1、kill掉歸檔進程（10g版本後不適用）

2、重啓數據庫（這招萬能）

3、log_archive_dest_2參數不要用別名，寫成連接字符串

比如：

alter system set log_archive_dest_2 = 'service="(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=standbynode)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=STDBY)))"' ;

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我還是想想，怎麼找機會重啓數據庫吧

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ps:20180614

使用了修改og_archive_dest_2的方法，可以解決掉問題：

alter system set log_archive_dest_2 = 'service="(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=32.114.111.11)(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=test_dg)))" LGWR ASYNC valid_for=(ONLINE_LOGFILES,PRIMAY_ROLE) DB_UNIQUE_NAME=test_dg' ;

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Adding an new Standby fails with error Ora-12154: TNS:could not resolve the connect identifier specified (文檔 ID 1240558.1)

轉到底部

---

In this Document

Symptoms

Changes

Cause

Solution

---

APPLIES TO:

Oracle Database - Enterprise Edition - Version 9.0.1.0 to 11.2.0.1 [Release 9.0.1 to 11.2]
Information in this document applies to any platform.

SYMPTOMS

** checked for relevance '23-Nov-2015' **

When adding or changing the parameter log_archive_dest_<n> to point to a newly created standby database, the archiver process for the new destination reports the following error in the alert log

Error 12514 received logging on to the standby
Errors in file /u01/diag/rdbms/prod/PROD/trace/PROD_arc0_2596.trc:
ORA-12514: TNS:listener does not currently know of service requested in connect descriptor

Corresponding archiver trace file may show:

Redo shipping client performing standby login
OCIServerAttach failed -1
.. Detailed OCI error val is 12514 and errmsg is 'ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
'
OCIServerAttach failed -1
.. Detailed OCI error val is 12514 and errmsg is 'ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
'
OCIServerAttach failed -1
.. Detailed OCI error val is 12514 and errmsg is 'ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
'
*** 2010-11-05 08:50:39.219 1117 krsh.c
Error 12514 received logging on to the standby
Error 12514 connecting to destination LOG_ARCHIVE_DEST_2 standby host 'remote_dest_new'

Query on V$ARCHIVE_DEST shows the following:

SQL> select dest_id,status,error from v$archive_dest; 

DEST_ID    STATUS    ERROR 
---------- --------- -----------------------------------------------------------------
         1 INACTIVE 
         2 ERROR     ORA-12514: TNS:listener does not currently know of service requested in connect descriptor 
         3 INACTIVE
...

 

 

Please note that this behavior seems to have changed in 11.2, the tnsnames.ora is now being read by the ARC processes when a new remote destination is added. It is unclear when exactly this was changed.

 

CHANGES

Added a new standby database and updated the tnsnames.ora with a new TNS alias for the new standby.

The same error can happen  on a existing standby database when tns-alias/log_archive_dest_x is changed:

Example:
log_archive_dest_2='service=ORCL2 ...' and ORCL2 has been defined in 
TNSNAMES.ORA
- edit TNSNAMES.ORA and copy or rename the ORCL2 entry to ORCL22
- run alter system set log_archive_dest_2='service=ORCL22 ...'
- TNS-12154 will be written to the alert file of the primary

CAUSE

After adding a new standby database, a corresponding new TNS alias entry was added to the tnsnames.ora on the primary node, but neither the instance nor the archiver processes were restarted.

The ARC processes read the tnsnames.ora only once during process initialization, any updates to the tnsnames.ora after startup will not be known to the ARC process and hence the error
ORA-12154: TNS:could not resolve the connect identifier specified
is reported when the ARC processes try to resolve the (new) value for the 'service' attribute.

SOLUTION

1. Shutdown and restart the primary database instance.

This will cause a (short) outage of the primary database and may not be feasible for this reason.

2. Use a connect descriptor for the 'service' parameter.

Instead of using a TNS alias for the service parameter (which requires a lookup of the tnsnames.ora file) one can use the connect descriptor itself.

Assume the following (new) entry in the tnsnames.ora on the primary node:

REMOTE_DEST_NEW = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = standbynode)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = STDBY) ) )

The corresponding 'alter system' command would then be:

alter system set log_archive_dest_2 = 'service="(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=standbynode)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=STDBY)))"' ;

Please note that there's a length limit for the log_archive_dest_<n> parameter, so this will only work if the length of the connect string plus the length of other attributes specified does not exceed this limit.

3. Kill the ARC processes of the primary instance.

With RDBMS releases <= 9.2 it was possible to stop and restart the archiver processes by issuing 'archive log stop' followed by 'archive log start'.
However these commands are no longer valid with 10g and above, so to cause a respawn of the archiver processes they must be killed, they will be restarted immediately by the instance.

This solution requires due care to avoid accidentally killing other vital background processes.

The following script (ksh,bash) may assist in identifying the correct ARC processes that need to be killed: