Oracle ACFS Support for Oracle Database File Mapping Views

Oracle ACFS supports Oracle Database file mapping views to the Oracle ASM device level.

Note:

This feature is available starting with Oracle Database 12c Release 1 (12.1.0.2).

The following database mapping views are supported by Oracle ACFS:

V$MAP_FILE
V$MAP_FILE_EXTENT
V$MAP_ELEMENT
V$MAP_FILE_IO_STACK

These V$MAP views are only refreshed by executing the procedure DBMS_STORAGE_MAP.MAP_ALL. The Oracle ACFS file mapping interface does not utilize the external fmputl process or its supporting libraries.

Note:

Oracle ACFS does not provide support for the V$MAP_SUBELEMENT view.

Before running any queries on the V$MAP views, ensure that the FILE_MAPPING initialization is set to TRUE, then run the DBMS_STORAGE_MAP.MAP_ALL procedure to build the mapping information for the entire I/O subsystem associated with the database. For example, connect as SYSDBA to the database instance and run the following:

SQL> ALTER SYSTEM SET file_mapping=true;

SQL> EXEC DBMS_STORAGE_MAP.MAP_ALL(10000);

The SQL statements in Example 2-12 to Example 2-15 are run from the Oracle Database instance.

Example 2-12 Viewing Oracle ASM information with V$MAP_ELEMENT

This example displays information from the V$MAP_ELEMENT view.

SQL> SELECT ELEM_NAME, ELEM_IDX, ELEM_TYPE, ELEM_SIZE, ELEM_DESCR 
       FROM V$MAP_ELEMENT;

ELEM_NAME      ELEM_IDX ELEM_TYPE   ELEM_SIZE ELEM_DESCR
------------ ---------- ---------- ---------- -----------------
+/dev/xvdd1           0 ASMDISK     117184512 TEST_0001
+/dev/xvdc1           1 ASMDISK     117184512 TEST_0000

Example 2-13 Viewing Oracle ACFS Data File Information with V$MAP_FILE

This example displays information from the V$MAP_FILE view.

SQL> SELECT FILE_NAME, FILE_MAP_IDX, FILE_TYPE, FILE_STRUCTURE, FILE_SIZE, 
      FILE_NEXTS FROM V$MAP_FILE WHERE REGEXP_LIKE(FILE_NAME, '*users01.dbf');

FILE_NAME                 FILE_MAP_IDX FILE_TYPE FILE_STRU FILE_SIZE FILE_NEXTS
------------------------- ------------ --------- --------- --------- ----------
/dbdata1/orcl/users01.dbf            4 DATAFILE  FILE          10256         41

Example 2-14 Viewing Element and File Offset Information with V$MAP_FILE_EXTENT

This example displays the element offset versus file offset information for each extent with V$MAP_FILE_EXTENT, specifying FILE_MAP_IDX equal to 4, which is the file map index of the /dbdata/orcl/users01.dbf file.

SQL> SELECT FILE_MAP_IDX, EXT_NUM, EXT_ELEM_OFF, EXT_SIZE, EXT_FILE_OFF, 
       EXT_TYPE, ELEM_IDX FROM V$MAP_FILE_EXTENT WHERE FILE_MAP_IDX=4; 

FILE_MAP_IDX    EXT_NUM EXT_ELEM_OFF   EXT_SIZE EXT_FILE_OFF EXT_TY   ELEM_IDX
------------ ---------- ------------ ---------- ------------ ------ ----------
           4          0     58105664        192            0 DATA            0
           4          1     58154752        256          192 DATA            1
           4          2     58089472        256          448 DATA            0
...
           4         39     58140928        256         9920 DATA            1
           4         40     58108160         88        10176 DATA            0
41 rows selected.

Example 2-15 Viewing Extent Information With V$MAP_FILE_IO_STACK

This example displays information from V$MAP_FILE_IO_STACK specifying FILE_MAP_IDX equal to 4. The V$MAP_FILE_IO_STACK view is similar to V$MAP_FILE_EXTENT, but the display groups contiguous extents which are on the same device or element and of the same size.

SQL> SELECT FILE_MAP_IDX, ELEM_IDX, CU_SIZE,STRIDE, NUM_CU,ELEM_OFFSET, 
       FILE_OFFSET FROM V$MAP_FILE_IO_STACK WHERE FILE_MAP_IDX=4;

FILE_MAP_IDX   ELEM_IDX    CU_SIZE     STRIDE     NUM_CU ELEM_OFFSET FILE_OFFSET
------------ ---------- ---------- ---------- ---------- ----------- -----------
           4          0        256       1024         10    58089472 448
           4          0        192          0          1    58105664 0
           4          0        256       1024          9    58105856 960
           4          0         88          0          1    58108160 10176
           4          1        256       1024         10    58138624 704
           4          1        256       1024         10    58154752 192

6 rows selected.