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Oracle® Database Reference
12c Release 1 (12.1)

E17615-24
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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