re size datafile oracle
The database is using Oracle Automated Storage Management, so the data files are not located in a normal file system where you can "cd" to the directory and see them. You would need to have privileges within the ASM management database and use a tool like "asmcmd" to see more information. As long as the database recognizes the file as online, you are fine. You do not need to take anything offline or jump through any other hoops. See this link for more info: http://www.oracle-wiki.net/startdocsusefuloraclecommands