ORA-12505:TNS:listener does not currently know of SID given in connect descriptor

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ORA-12505:TNS:listener does not currently know of SID given in connect descriptor

For an explanation of this error message, refer to the article on ORA-12514.
The main difference lies in the fact that the client is using a SID instead of a service name, hence the returned error message is slightly different.
I've seen this error frequently when trying to connect to a freshly started db using SQL Developer, prior that the instance registered itself with the listener.

Listener refused the connection with the following error:
ORA-12505, TNS:listener does not currently know of SID given in connect descriptor
The Connection descriptor used by the client was: 192.168.1.30:1521:orcl11

Vendor code 0

See message translations for ORA-12505 and search additional resources.

ORA-12541: TNS:no listener

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ORA-12541: TNS:no listener

This error can be seen when trying to connect to a database instance from a client program and the listener service is down or has not been started automatically after a reboot.
Note however that you can also get this error when trying to reach the listener on the wrong TCP port: by default a listener is configured to listen on port 1521 but a DBA could have changed the default port value in case the server runs multiple oracle instances or different database server versions. So, if the listener is configured to listen, let's say, on port 1522 and the TNSNAMES.ora file located in the ORACLE_HOME/network/admin folder contains port 1521 instead, you'll get ORA-12541, even if the listener is up and running.

If you are experiencing this error in a client/server environment and you are not the database administrator, then you should contact the DBA and ask for help. The oracle utility TNSPING should also help you out in the troubleshooting process as it will display all the relevant information.

On Windows platforms the listener is a Windows service that is usually set to start up automatically.
In Oracle XE for Windows, the service name is OracleXETNSListener.
In other versions of Oracle database for Windows, the name is automatically generated upon creating a listener with the Oracle Net Service configuration console, but usually, for a single instance installation, the default name will be OracleOracleHomeNameTNSListener, i.e. OracleOraHome101TNSListener for a database version 10.1 whose oracle home is named OraHome101. You can also check the listener status by executing LSNRCTL from the command line in much the same way as you'd do it on a Unix platform, as explained below.

On a Unix server, if you hold the required privileges, you can check the listener status by executing the listener configuration utility LSNRCTL and issuing the command STATUS:
if the result is like the following:

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=dbserv)(PORT=1521)))
TNS-12541: TNS:no listener
TNS-12560: TNS:protocol adapter error
TNS-00511: No listener
 Linux Error: 111: Connection refused

then the listener is not running and you can start it with the command START.

If connecting from SQLDeveloper from a client machine, it's very likely that you get instead the following error message:

An error was encountered performing the requested operation:
Io exception: The Network Adapter could not establish the connection
Vendor code 17002

See message translations for ORA-12541 and search additional resources

Creating an ISO image from a zip file

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Quick link to the original posting, my thanks to Gary for sharing this useful tip for MAC OS X.

Some days ago i was working via SSH/VNC on my Mac OS X server where i needed to install Oracle 11G for linux 64-bit.

One of the great features of VMWare Fusion (present also in other VMWare products) is the possibility of attaching an ISO disk image as if it were a physical CD or DVD, avoiding the physical burning of CD or DVD media.
Unfortunately i hadn't such ISO image available, i had instead the source files in a zip file downloaded on the Mac.

I could have copied the files from the host to the guest operating system or executed from a shared folder, but i preferred to see if i could find a way of stuffing the content of a directory into an ISO image file using plain OS X commands.

Fortunately, Google came to the rescue and i stumbled upon Gary's blog, where i found such great tip, that i easily adapted for my case:

First of all unzip the archive:

unzip linux.x64_11gR1_database.zip

This will create a subdirectory called "database" into the current one.
Finally, create the ISO disk image:

hdiutil makehybrid -o oracle11g.iso -iso -joliet -hfs -udf database

Now you can mount the resulting ISO file through VMWare Fusion.
If for some reason you cannot run the installer, e.g. you get a "Permission denied" error, it can be that the "cdrom" is not mounted properly. By mounted properly i mean that a line like the following must be present in the /etc/fstab file:

/dev/cdrom   /mnt/cdrom  auto  exec,noauto,owner,ro 0 0

For some reason this line was present in a Xubuntu Linux VM i've created, but was not present in Oracle Linux and i don't really know if it is a "quirk" of the auto-mount feature or a normal behavior.