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Oracle® Database Reference 10g Release 2 (10.2) Part Number B14237-02 |
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# V$ASM_DISKGROUP

In an Automatic Storage Management instance, `V$ASM_DISKGROUP` displays one row for every disk group discovered by the Automatic Storage Management instance. In a database instance, `V$ASM_DISKGROUP` displays one row for every Automatic Storage Management disk group mounted by the local Automatic Storage Management instance.

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
`UNBALANCED` | `VARCHAR2(1)` | Indicates whether the disk group requires a rebalance, for example, if the instance crashed while a rebalance operation was pending (`Y`) or not (`N`)
`COMPATIBILITY` | `VARCHAR2(60)` | The minimum software version required for an ASM instance to mount this disk group
`DATABASE_COMPATIBILITY` | `VARCHAR2(60)` | The 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`.