V$ASM_DISKGROUP

V$ASM_DISKGROUP displays one row for every ASM disk group discovered by the 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)
`BLOCK_SIZE`	`NUMBER`	Automatic Storage Management 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: `CONNECTED` - Disk group is in use by the database instance `BROKEN` - Database instance lost connectivity to the Automatic Storage Management instance that mounted the disk group `UNKNOWN` - Automatic Storage Management instance has never attempted to mount the disk group `DISMOUNTED` - Disk group was cleanly dismounted by the Automatic Storage Management instance following a successful mount `MOUNTED` - Instance is successfully serving the disk group to its database clients
`TYPE`	`VARCHAR2(6)`	Redundancy type for the disk group: `EXTERN` `NORMAL` `HIGH`
`TOTAL_MB`	`NUMBER`	Total capacity of the disk group (in megabytes)
`FREE_MB`	`NUMBER`	Unused capacity of the disk group (in megabytes)
`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 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

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.