Oracle ACFS supports Oracle Database file mapping views to the Oracle ASM device level. For information about file mapping to Oracle ASM files, refer to "Oracle Database File Mapping for Oracle ASM Files".
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$MAP views are only refreshed by executing the procedure DBMS_STORAGE_MAP.MAP_ALL. The Oracle ACFS file mapping interface does not utilize the external fmputl process or its supporting libraries.
Oracle ACFS does not provide support for Oracle Database file mapping on Windows.
Oracle ACFS does not provide support for the V$MAP_SUBELEMENT view.
Before running any queries on the V$MAP views, ensure that the FILE_MAPPING initialization is set to TRUE, then run the DBMS_STORAGE_MAP.MAP_ALL procedure to build the mapping information for the entire I/O subsystem associated with the database. For example, connect as SYSDBA to the database instance and run the following:
SQL> ALTER SYSTEM SET file_mapping=true; SQL> EXEC DBMS_STORAGE_MAP.MAP_ALL(10000);
The SQL statements in Example 12-12 to Example 12-15 are run from the Oracle Database instance. Example 12-12 displays information from the V$MAP_ELEMENT view.
Example 12-13 displays information from the V$MAP_FILE view.
Example 12-14 displays the element offset versus file offset information for each extent with V$MAP_FILE_EXTENT, specifying FILE_MAP_IDX equal to 4, which is the file map index of the /dbdata/orcl/users01.dbf file.
Example 12-15 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$MAP_FILE_EXTENT, but the display groups contiguous extents which are on the same device or element and of the same size.
Oracle Database Administrator's Guide for information about the Oracle Database File Mapping Interface
Oracle Database Reference for details about the V$MAP views
Example 12-12 Viewing Oracle ASM information with V$MAP_ELEMENT
SQL> SELECT ELEM_NAME, ELEM_IDX, ELEM_TYPE, ELEM_SIZE, ELEM_DESCR
FROM V$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 12-13 Viewing Oracle ACFS Data File Information with V$MAP_FILE
SQL> SELECT FILE_NAME, FILE_MAP_IDX, FILE_TYPE, FILE_STRUCTURE, FILE_SIZE,
FILE_NEXTS FROM V$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 12-14 Viewing Element and File Offset Information with V$MAP_FILE_EXTENT
SQL> SELECT FILE_MAP_IDX, EXT_NUM, EXT_ELEM_OFF, EXT_SIZE, EXT_FILE_OFF,
EXT_TYPE, ELEM_IDX FROM V$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 12-15 Viewing Extent Information With V$MAP_FILE_IO_STACK
SQL> SELECT FILE_MAP_IDX, ELEM_IDX, CU_SIZE,STRIDE, NUM_CU,ELEM_OFFSET,
FILE_OFFSET FROM V$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.