Control File

How to Check Control File Size

Control file is a file that have several file attributes including size, but when database is stored upon raw devices, your control files are just symbolic links that represent raw devices. There’s no way to check the usage of a raw device.

Here are several ways to check the size of controlfile.
  1. Query v$controlfile_record_section.
  2. SQL> SELECT 2* SUM(record_size*records_total)/1024/1024 "SIZE (MB)" FROM v$controlfile_record_section;
    You can see I double the size of the sum of all the records size. The result is not accurate, but it’s close to the actual size, just a little less than the actual.
  3. By an indirect approach, to backup current control file to check the control file size.
  4. RMAN> BACKUP CURRENT CONTROLFILE FORMAT '/tmp/control_backup.ctl';
    $ ls -l /tmp/con*
    -rw-r----- 1 oracle asmadmin 19955712 Aug 18 10:29 /tmp/control_backup.ctl
  5. For 11g, query v$controlfile directly.
  6. SQL> SELECT (block_size * file_size_blks)/1024/1024 "SIZE (MB)" FROM v$controlfile;
    The result is more accurate than query v$controlfile_record_section. But for 9i, 10g ,this statement can not be used, because there is no “block_size” and “file_size_blks” column in v$controlfile in 9i and 10g.
  7. For 11g, list file size via ASMCMD with grid owner.
  8. $ asmcmd
    ASMCMD> cd +data/dbname/controlfile
    ASMCMD> ls -s
    Block_Size  Blocks     Bytes     Space  Name
         16384    1215  19906560  78643200  Current.329.798435911

    The size is on the column “Bytes”.
Using command “dd” to output a raw device to a regular file as following command does not work, which will dump all blocks of the raw device whether the blocks are used or not.
# dd if=/dev/vg1/rlv01 of=/tmp/control_output.ctl bs=4k

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