7.63 V$ASM_DISKGROUP

V$ASM_DISKGROUP displays one row for every Oracle Automatic Storage Management (Oracle ASM) disk group discovered by the Oracle ASM instance on the node.

Column Datatype Description

GROUP_NUMBER

NUMBER

Cluster-wide number assigned to the disk group (primary key)

NAME

VARCHAR2(30)

Name of the disk group

SECTOR_SIZE

NUMBER

Physical block size (in bytes)

LOGICAL_SECTOR_SIZE

NUMBER

This column represents the logical sector size value of the disk group in bytes. This is the smallest possible I/O that can be done in this disk group. Any I/O smaller than the logical sector size will cause an assert in the code.

If the value of the LOGICAL_SECTOR_SIZE column is 512, while the value in the SECTOR_SIZE column is 4096, then the disk group supports 512 sector size emulation. This means that I/O operations can be both 512 or 4096 aligned. For example, this means that you can have redo log files with a file block size of 512 bytes in this disk group that can be both read and written to, as well as create new redo log files with a file block size of 4096 bytes.

BLOCK_SIZE

NUMBER

Oracle ASM metadata block size (in bytes)

ALLOCATION_UNIT_SIZE

NUMBER

Size of the allocation unit (in bytes)

STATE

VARCHAR2(11)

State of the disk group relative to the instance:

  • BROKEN - Database instance lost connectivity to the Oracle ASM instance that mounted the disk group

  • CONNECTED - Disk group is in use by the database instance

  • DISMOUNTED - Disk group was cleanly dismounted by the Oracle ASM instance following a successful mount

  • MOUNTED - Instance is successfully serving the disk group to its database clients

  • QUIESCING - CRSCTL utility attempted to dismount a disk group that contains the Oracle Cluster Registry (OCR). The disk group cannot be dismounted until Cluster Ready Services (CRS) exits, because the disk group contains the OCR.

  • RESTRICTED - A disk group mounted in this mode can only be seen by this Oracle ASM instance for maintenance purposes

  • UNKNOWN - Oracle ASM instance has never attempted to mount the disk group

TYPE

VARCHAR2(6)

Redundancy type for the disk group:

  • EXTEND

  • EXTERN

  • FLEX

  • HIGH

  • NORMAL

TOTAL_MB

NUMBER

Total capacity of the disk group (in megabytes)

FREE_MB

NUMBER

Unused capacity of the disk group (in megabytes)

HOT_USED_MB

NUMBER

Number of used megabytes in the hot region

COLD_USED_MB

NUMBER

Number of used megabytes in the cold region

REQUIRED_MIRROR_FREE_MB

NUMBER

Amount of space that is required to be available in a given disk group in order to restore redundancy after one or more disk failures. The amount of space displayed in this column takes mirroring effects into account.

USABLE_FILE_MB

NUMBER

Amount of free space that can be safely utilized taking mirroring into account and yet be able to restore redundancy after a disk failure

OFFLINE_DISKS

NUMBER

Number of disks in the disk group that are currently offline

COMPATIBILITY

VARCHAR2(60)

Minimum software version required for an Oracle ASM instance to mount this disk group

DATABASE_COMPATIBILITY

VARCHAR2(60)

Minimum software version required for a database instance to use files in this disk group

VOTING_FILES

VARCHAR2(1)

Indicates whether the disk contains voting files (Y) or not (N)

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

For this view, the value is always 0.

Note:

The GROUP_NUMBER, TOTAL_MB, and FREE_MB columns are only meaningful if the disk group is mounted by the instance. Otherwise, their values will be 0.

See Also:

Oracle Automatic Storage Management Administrator's Guide for additional information about using views to display Oracle ASM information