ODBC DSNs are saved in odbc.ini file. The default locations to save the odbc.ini file are:
User DSNs: "~/Library/ODBC/"
System DSNs: "/Library/ODBC/"
Optionally, the ODBCINI environment variable can point to an odbc.ini file present in non-default locations.
ODBC DSNs can be configured using the GUI Administrator tool or manually.