9.71 V$MAP_FILE_IO_STACK

V$MAP_FILE_IO_STACK displays the hierarchical arrangement of storage containers for files. Each row in the view represents a level in the hierarchy.

Column Datatype Description

FILE_MAP_IDX

NUMBER

File index (corresponds to FILE_MAP_IDX in V$MAP_FILE)

DEPTH

NUMBER

Element depth within the I/O stack

ELEM_IDX

NUMBER

Index corresponding to the element

CU_SIZE

NUMBER

Contiguous set of logical blocks of the file (in HKB units) that is resident contiguously on the element

STRIDE

NUMBER

Number of HKB between contiguous units (CU) in the file that are contiguous on this element. Used in RAID5 and striped files.

NUM_CU

NUMBER

Number of contiguous units that are adjacent to each other on this element that are separated by STRIDE HKB in the file. In RAID5, the number of contiguous units also include the parity stripes.

ELEM_OFFSET

NUMBER

Element offset in HKB units

FILE_OFFSET

NUMBER

Offset in HKB units from the start of the file to the first byte of the contiguous units

DATA_TYPE

VARCHAR2(15)

Datatype:

  • DATA

  • PARITY

  • DATA AND PARITY

PARITY_POS

NUMBER

Position of the parity. Only for RAID5. This column is needed to distinguish the parity from the data part.

PARITY_PERIOD

NUMBER

Parity period. Only for RAID5.

ID

NUMBER

Unique identifier

PARENT_ID

NUMBER

Parent identifier

CON_ID

NUMBER

The ID of the container to which the data pertains. Possible values include:

  • 0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.

  • 1: This value is used for rows containing data that pertain to only the root

  • n: Where n is the applicable container ID for the rows containing data