10 Replies Latest reply: Mar 2, 2014 1:18 AM by alammo1 RSS

    Oracle Database strange behavior

    alammo1

      Hi,

       

      I am doing some Backup & Recovery scenarios practice on my test machine. I am using 10.2.0 Oracle Database on Linux AS4 for this testing.

       

      I am connected as sysdba in one session and in another session I deleted all the "controlfiles" from the "oradata" directory

       

      Even when the controlfiles are deleted, I am still able to perform the following things:

       

      1. I am able to issue a checkpoint:

       

      SQL> alter system checkpoint;

       

      System altered.

       

      SQL> /

       

      System altered.

       

      SQL> /

       

      System altered.

       

      SQL> /

       

      System altered.

       

      SQL> /

       

      System altered

       

      2. I am able to switch logfiles:

       

      SQL> alter system switch logfile;

       

      System altered.

       

      3. I am able to see information from v$controlfile dynamic view:

       

      SQL> select * from v$controlfile;

       

      STATUS  NAME                                               IS_ BLOCK_SIZE

      ------- -------------------------------------------------- --- ----------

      FILE_SIZE_BLKS

      --------------

              /u01/oracle/oradata/db/control01.ctl               NO       16384

                 430

       

              /u01/oracle/oradata/db/control02.ctl               NO       16384

                 430

       

              /u01/oracle/oradata/db/control03.ctl               NO       16384

                 430

       

       

      4. I am even able to create a new tablespace in the system:

       

      SQL> create tablespace uat datafile '/u01/oracle/oradata/db/uat01.dbf' size 5M;

       

      Tablespace created.

       

      ###################################################################

       

      Could someone please explain how is all this possible. Is there any kind of buffer where controlfile runtime information is loaded which is being used by the DB.

       

      Thanks & Regards,

      Muneer.