what will happen, if we miss the '+' sign while adding datafile to ASM in oracle 11g database? Whether datafile added will be ASM based or Non-ASM based?

  • 1
    Non-ASM based. It will try to create the datafile in a default location (in db_create_file parameter, if I'm not mistaken) Commented May 18, 2017 at 12:48
  • @Ronato Afonso Thanks for the suggestion..but what happens if the db_create_file value in my database is empty? Commented May 20, 2017 at 10:46
  • Show me the DDL script. Commented May 22, 2017 at 11:13
  • alter tablespace CWSC add datafile 'DATA' size 100M AUTOEXTEND ON; Commented May 25, 2017 at 5:59

1 Answer 1


If you miss the '+' sign, there will be several scenarios:

  1. db_create_file_dest is set and points to ASM (i.e: +DATA): The database will take 'DATA' as an alias and will create ASM file on the destination associated with the 'DATA' alias that will be located at the ASM +DATA root directory.
  2. db_create_file_dest is set and points to filesystem: It should be quite obvious that you'll have a new 'DATA' file in the location pointed at the parameter.
  3. db_create_file_dest is not set (worst scenario): The database will default to $ORACLE_HOME/dbs and create a datafile there with the name 'DATA'.

A final piece of advice: Set the db_create_file_dest to point to the ASM DATA disk group and remove the datafile name parameter from your command:

alter tablespace CWSC add datafile size 100M AUTOEXTEND ON;

As you may know, even if you give a name to the datafile, when it's created on ASM, that name becomes an alias and the real filename is set by the ASM instance itself.

I hope this info helps you.

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