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Oracle 视图 V$MAP_FILE_IO_STACK 官方解释，作用，如何使用详细说明

本站中文解释

V$MAP_FILE_IO_STACK视图报告文件IO栈的映射关系，其使得DBA可以更好地了解到操作系统IO栈是由哪些文件组成的。我们可以通过该视图查看在操作系统IO栈中，哪些文件参与了IO操作。

使用方法：

1、查询操作系统IO栈中，哪些文件参与了IO操作

例如：

SELECT file#, layer, owner, phyrds,phywrts, reads, writes
FROM v$map_file_io_stack
WHERE layer > 0;

2、查询某个操作系统IO栈的详细信息

例如：

SELECT * FROM v$map_file_io_stack
WHERE stack_id = ;

官方英文解释

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


数据运维技术 » Oracle 视图 V$MAP_FILE_IO_STACK 官方解释，作用，如何使用详细说明
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