Running two diff MySQL versions at once?

It's not complicated at all.

The main thing is to run them on different ports. When you specify in your applications where to connect for an older version to its regular port, for others - new port.

You also must have different socket, shared memory base, pid file.

If you want logging - make sure they have separate logging files.

so next options must be unique for each instance:

--port=port_num

--socket=path

--shared-memory-base-name=name

--pid-file=file_name

for logging:

--log=file_name

--log-bin=file_name

--log-update=file_name

--log-error=file_name

--bdb-logdir=file_name

Addition:

Here is a good description for both *nix and Windows.

http://dev.mysql.com/doc/refman/5.0/en/multiple-se...