Oracle ACFS Support for Oracle AI Database File Mapping Views

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

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 AI 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.