I am wondering if anyone has tried to connect from ArcGIS 10, to an oracle database stored on a Linux server? I have no problems connecting to oracle from Arc when the data is stored on a windows box, but no matter the different combinations of host name / server name I insert to try and connect to the database which is stored on a Linux box I get an error.
Even if its a case of this is not possible, it would be nice to know so I can try and proceed down a different route.
Connecting to a linux database is absolutely no different from connecting to a database on Windows, or any other platform for that matter. The interconnect protocol (SQL*net) is the same everywhere. The platforms for the client and server play no role here, neither does the fact that one is 32-bit and the other is 64-bit. Also the versions of the Oracle client and the Oracle server play little role: the protocol exchange is such that it will automatically adapt to the versions at both ends. So interconnection works with all reasonably recent versions of Oracle (say 10gR2, 11gR2, 12cR1) but they should also work with older versions (9i, even 8i). I have seen some incompatibilities reported between a 12c client and an 8.0 server ... but such is life.
What probably happens is that your Windows database runs on the same server as your ArcGIS 10 server whereas your Linux database runs on a different server. In one case you use possibly a direct connection (no IP) or maybe a local connection (localhost), whereas the connection to the Linux database is obviously remote and needs the full connection details: server name or IP address, TNS listener port, database service name or SID (and of course the proper credentials).
For a start it would really help if you tell us the exact error you are getting and the connection details you specify (server, port, service names). Connecting to an Oracle Database can fail for a variety of reasons, but they always have to do with some mis-configuration, either client or server side.
Debugging those issues can be very difficult when using client tools (like ArcGIS) that sometimes obfuscate the error messages they receive into some generic "connection failure" message, leaving you guessing and poking.
Debugging is best done in steps, using simple tools:
1) Confirm that the server is reachable:
ping <database_server>
2) Confirm that the TNS listener is reachable on the port you expect, and knows about your database:
tnsping <database_server>:<port>/<database_service>
for example:
tnsping db_server.acme.com:1521/orcl121.local
3) Confirm that the database is up and running and connected to your listener, and also that you are using the proper credentials.
sqlplus <username>/<password>@<database_server>:<port>/<database_service>
If you are not familiar with those techniques, I recommend you seek assistance from your database administrator.
BTW, what version of Oracle are we talking about ? On Windows ? On Linux ?
iptables firewall must be configured to allow connection through SQL*Net port 1521 (or whichever non-default port was chosen).