INFO: Oracle TRC Files and MTS

ID: Q246006

The information in this article applies to:

Microsoft Transaction Server, versions 1.0, 2.0

SUMMARY

Under some circumstances your Oracle database may produce .trc files when used with Microsoft Transaction Server. This document describes what TRC files are, why TRC files produce, and what you can do to eliminate TRC files.

MORE INFORMATION

What are TRC files?

TRC files are produced by your Oracle database. The online Oracle documentation describes the Oracle trace facility as follows:


The trace facility allows a network or database administrator to obtain more information on the internal operations of the components of an Oracle application network than is provided in a log file. Tracing an operation produces a detailed sequence of statements that describe the events as they are executed. All trace output is directed to trace output files that can be evaluated to identify the events that led to an error.

Who produces TRC files?

Your Oracle database software produces .trc files. TRC files are designed to provide more information about errors that are detected and reported by Oracle database software. Several Oracle components are capable of producing TRC file. For the remainder the document focuses on the TRC files produced by Oracle's XA facility.

Does Microsoft software ever produce TRC files?

No, Microsoft software never produces .trc files.

Is there documentation describing Oracle TRC files?

The Oracle XA trace facility is described in the online "Oracle8 Documentation Library" that accompanies the Oracle8 product. To locate this documentation, do the following:

In the "Oracle8 Documentation Library" select "Oracle8"

Go to the "General Oracle8 Enterprise Edition" heading in the table of contents and select "Application Developer's Guide".

Go to "Chapter 18 Oracle XA" in the table of contents and select "Troubleshooting" and then "Trace Files".

What information do TRC files contain?

A typical Oracle XA TRC file contains information like shown in the following

093452.280:309.309.1:
ORACLE XA: Version 7.3.4.0.0. RM name = 'Oracle_XA'.
093452.280:309.309.1:
xaolgn: XAER_RMERR; upiahs failed. ORA-12154.
093452.280:309.309.1:
ORA-12154: TNS: The name of the Service was not resolved

Why are TRC files being produced?

A TRC file is produced when MS DTC attempts to perform an XA operation with your Oracle database and the Oracle XA operation reports an error. The TRC files are the means by which Oracle reports additional error information. Some XA errors result from normal XA database operations such as trying to commit or rollback a transaction. Other XA errors may result when MS DTC attempts to perform XA recovery with your Oracle database.

Understanding how XA Recovery works may help you better understand how XA recovery may result in TRC files.

Whenever MTS opens an Oracle database connection under XA transaction control, MS DTC writes a log record to the Dtcxatm.log file. These log records are used to keep track of each active Oracle database connection. The log record also contains the open string used to open the Oracle database connection. The MS DTC transaction manager uses this open string to reconnect to the Oracle database if XA recovery is necessary. Whenever MTS successfully closes an Oracle database connection, the corresponding log record along with its open string is deleted from the Dtcxatm.log file.

If an Oracle database, an MTS host application process, or the MS DTC transaction manager process fails while an Oracle database connection is open, MS DTC must perform database recovery. If the Oracle database fails while MS DTC remains active, MS DTC immediately attempts to reconnect to the Oracle database and perform recovery. If the MS DTC transaction manager process fails, MS DTC attempts to reconnect to the Oracle database and perform XA recovery as soon as MS DTC is restarted.

MS DTC performs recovery by reading the Dtcxatm.log file to determine Oracle database connections, if any, need recovery. It retrieves the open string for the Oracle database connection and opens the database. MS DTC then sends an XA_RECOVER request to the Oracle database. In response to the XA_RECOVER request, the Oracle database sends MS DTC a list of the transactions that were active or in-doubt at the time of the failure. MS DTC tells Oracle whether each active or in-doubt transaction committed or aborted. Recovery completes when the Oracle database has been told the outcome of all active or in-doubt transaction. When recovery completes, MS DTC deletes the log record for that Oracle connection from its Dtcxatm.log file.

If MS DTC cannot recover the Oracle database connection, either because MS DTC cannot open the Oracle database or because of some other recovery-related error, MS DTC delays for one minute and then retries recovery. MS DTC continues retrying recovery every minute until recovery is successful. MS DTC is persistent in retrying recovery because the Oracle database is required to hold record locks for all active or in-doubt transactions until recovery is complete.

The Oracle database may produce a .TRC file on each unsuccessful recovery attempt. If recovery fails repeatedly, many Oracle TRC files may be produced.

Why does the system sometimes stop producing TRC files after you delete the Dtcxatm.log file?

If you delete the MS DTC Dtcxatm.log file, you are deleting all information concerning unrecovered Oracle database connection. This prevents MS DTC from attempting to perform Oracle database recovery. When MS DTC stops trying to recover your database you may no longer get TRC files. The problem with deleting the log file is that it may leave your Oracle database in an inconsistent unrecovered state.

If you are getting unwanted Oracle Trace files, do the following:

Make sure that Oracle XA Transaction Support is Enabled

One of the most common reasons for getting trace files is that Oracle has not been properly configured to support XA recovery. In this case, every attempt to perform Oracle XA recovery may fail. This can result in hundreds or thousands of Oracle TRC files like the following:
```
121454.240:244.244.1:
ORACLE XA: Version 7.3.4.0.0. RM name = 'Oracle_XA'.

121454.240:244.244.1:
xaofetch: XAER_RMERR; upipse rtn ORA-942; sql_stmt=SELECT k2gtifmt,
k2gtitid_ext, k2gtibid FROM sys.v$xatrans$

121454.240:244.244.1:
ORA-00942: table or view does not exist 
```
You can correct this problem by enabling Oracle XA transaction support as described in the following article:
Q193893 Using Oracle Databases with Microsoft Transaction Server

Make sure that Oracle is Not Tracing XA_RDONLY Return Values.

Make certain that you are running at least version 7.3.3.5 of Oracle. The Oracle 7.3.3.5 Readme entry for bug 460407 reports that on earlier Oracle releases, the Oracle xa_prepare call logged an error when it received a return code of XA_RDONLY. This is actually a legal return code for an Oracle xa_prepare call. Oracle should only have logged this message if extended tracing was requested (dbgfl > 0).
Here is an example of the TRC file produced when XA_RDONLY calls are erroneously logged.

122242.420:72.72.6:
ORACLE XA: Version 7.3.3.0.0. RM name = 'Oracle_XA'.

122242.420:72.72.6:
xaoprepare: xaoswitchprep rtn 3.

Install MS DTC Hot Fix 809

This hot fix corrects a problem in the MS DTC transaction manager. MS DTC sometimes failed to properly delete XA database recovery information from the Dtcxatm.log file. The Dtcxatm.log file should typically be less than one megabyte in size. Under some circumstances the log file could grow to hundreds of megabytes.

You may obtain MS DTC hot fix 0809 from:

ftp://ftp.microsoft.com/bussys/distapps/MTS/Public-Fixes/usa/DTC/SvcPack/.

Ensure that Your Oracle Name Server is Configured Properly.
The following TRC information is sometimes seen when Oracle Name Server is not configured properly.

092813.283:222.222.13687:
ORACLE XA: Version 7.3.4.0.0. RM name = 'Oracle_XA'.

092813.283:222.222.13687:
xaolgn: XAER_RMERR; upiahs failed. ORA-12154.

092814.283:222.222.13687:
ORA-12154: TNS:could not resolve service name

How can you control where TRC files are written?

You can control the location of the TRC files if you have installed the Windows NT 4.0 Service Pack 4 or later. Do this as follows:

Make sure that the Mtxoci.dll installed on your MTS system is version 1998.08.762.0 or later. Version 1998.08.762.0 was released with the NT 4.0 Service Pack 4 release. It was the first version of the Mtxoci.dll that allows you to control the location of Oracle trace files.

Use the Explorer to find and delete any existing Oracle trace files on your system. These files have names ending with the suffix ".trc". By deleting any obsolete trace files, you make it easier to find any newly created ones.

Run REGEDIT to create the following registry key:
```
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Transaction Server\Local Computer\My Computer\OracleTraceFilePath

Give this key the following REG_SZ value:

C:\OraTrace  
```
You may choose a different disk drive and directory for the trace files if you want.

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

Use the Explorer to create the Oracle trace file directory. For example, create the directory "OraTrace" on the "C" drive.

Stop the MTS package that is accessing the Oracle database. By stopping the package you ensure that all existing Oracle database connections are closed and that new Oracle database connections will be opened when the MTS component is next invoked. These newly opened Oracle database connections use the new trace directory location.

REFERENCES

For additional information, please see the following article(s) in the Microsoft Knowledge Base:

Q193893 Using Oracle Databases with Microsoft Transaction Server

Additional query words: MTS, Oracle, trace

Keywords : kbMTS kbMTS100 kbMTS200 kbOracle kbDSupport
Version : winnt:1.0,2.0
Platform : winnt
Issue type : kbinfo