How to point to 32 bit IBM DB2 ODBC driver on 64-bit Microsoft system?

Question
I want to create a 32 bit ODBC DSN pointing to 32 bit IBM DB2 ODBC driver for my 32 bit application in a 64-bit environment. How do I run the 32-bit ODBC administrator in a 64-bit environment? 
Cause
The Microsoft ODBC Data Source Administrator is used by DB2 to create an ODBC DSN.


By default on a Windows 64-bit server, when the 'MicroSoft ODBC Data Source administrator' is run, it will launch the 64-bit version of odbcad32.exe, which can be used to create DSNs pointing to 64-bit IBM DB2 ODBC drivers only. 


If you have 32-bit applications running on a 64-bit Windows server, they will need to use the 32-bit ODBC driver. To create DSNs pointing to 32-bit IBM DB2 ODBC driver, the 32-bit 'MicroSoft ODBC Data Source administrator' must be used. 


Answer
First, it is good to note that both 32-bit and 64-bit ODBC drivers are available on a Windows 64-bit system. Here is where they are located. 


32-bit "IBM DB2 ODBC DRIVER" is registered under:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\ODBC\ODBCINST.INI\
Driver ---> ~\SQLLIB\BIN\DB2CLI.DLL
Setup  ---> ~\SQLLIB\BIN\DB2ODBC.DLL


64-bit "IBM DB2 ODBC DRIVER" is registered under:
HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBCINST.INI\
Driver ---> ~\SQLLIB\BIN\DB2CLIO.DLL
Setup  ---> ~\SQLLIB\BIN\DB2ODBC64.DLL




Next it will be helpful to understand how to create a DSN using a specific driver.




Creating DSN pointing to 32-bit IBM DB2 ODBC driver:
Microsoft Windows 64-bit platforms maintain a compatibility feature which enables a 32-bit application to run transparently in a 64-bit environment, known as WOW64, (Windows-32-on-Windows-64). This maintains its own copy of the registry that is only for 32-bit applications. 


The data sources using 32-bit IBM DB2 ODBC drivers can be created by using the 32-bit Microsoft ODBC data Source Administrator:  C:\WINDOWS\SysWOW64\odbcad32.exe


Using Windows Explorer, browse to the C:\WINDOWS\SysWOW64\odbcad32.exe and double click on the odbcad32.exe to bring up the 32-bit ODBC Data Source administrator.

Example:

Using the 32-bit Data Source Administrator, a new ODBC data source can be created for the 32-bit IBM DB2 ODBC driver (DB2CLI.DLL). If multiple DB2 copies are installed, drivers from all of those copies will be listed.
Example:

Move the horizontal scroll bar to the right, to see the File column and the 32-bit IBM DB2 ODBC driver - DB2CLI.DLL listed and select one.
Example:

To complete the process, select a driver and then follow the prompts to create the DSN.






Creating DSN pointing to 64-bit IBM DB2 ODBC driver:
To open the ODBC Data Source Administrator, follow the below steps:
1. On the Start menu, click Control Panel.
2. In Control Panel, click Administrative Tools.
3. In Administrative Tools, click Data Sources (ODBC).


By default when ODBC administrator is open in 64-bit Windows, it will launch 64-bit 'Micorsoft ODBC Data Source Administrator' which is WINDOWS\system32\odbcad32.exe (the 64-bit version). 


Example:

Using the above 64-bit Data Source Administrator, new ODBC data source can be created for the 64-bit IBM DB2 ODBC driver(DB2CLIO.DLL) only. If multiple DB2 copies are installed, drivers from all of those copies will be listed.


Example:

Move the horizontal scroll bar to the right, to see the File column and the 64-bit IBM DB2 ODBC driver -DB2CLIO.DLL listed and select one.


Example:

4. To complete the process, select a driver and then follow the prompts to create the DSN.