I have created a linked Oracle server in SQL Server 2012 using Oracle Provider for OLE DB and TNSNAMES.ORA (the Oracle database is clustered and, as far as I know, no other connection method works with clustered servers). This works fine.
Now the Oracle database has been moved to another cluster, so I edited TNSNAMES.ORA. Oracle SQL Developer works fine.
It seems that SQL Server doesn't re-read TNSNAMES.ORA but stores the connection details internally, because even after a server reboot all queries time out.
Does anyone know of a solution other than deleting and recreating the linked server ?
(That's what I did to resolve my issue, but it shouldn't be that hard !)