ASM Dynamic Views: ASM Instance Information

V$ASM_ALIAS  Shows every alias for every disk group mounted by the ASM instance
V$ASM_CLIENT  Shows which database instance(s) are using any ASM disk groups that are being mounted by this ASM instance
V$ASM_DISK     Lists each disk discovered by the ASM instance, including disks that are not part of any ASM disk group
V$ASM_DISKGROUP Describes information about ASM disk groups mounted by the ASM instance
V$ASM_FILE Lists each ASM file in every ASM disk group mounted by the ASM instance
V$ASM_OPERATION   Like its counterpart, V$SESSION_LONGOPS, it shows each long-running ASM operation in the ASM instance
V$ASM_TEMPLATE Lists each template present in every ASM disk group mounted by the ASM instance
V$ASM_DISKGROUP Shows one row per each ASM disk group that’s mounted by the local ASM instance
V$ASM_DISK Displays one row per each disk in each ASM disk group that are in use by the database instance
V$ASM_CLIENT Lists one row per each ASM instance for which the database instance has any open ASM files

ASM File Names:  Example ASM1DG1.ORCL.DATAFILE.TBSASM.257.1
A fully-qualified file name comprises the following five components, and always ends with a special number pair:<group>. The name of the ASM disk group.
<dbname>. The database that owns this ASM file.
<file type>. The Oracle file type (e.g. DATAFILE, ARCHIVELOG, CONTROLFILE).
<tag>. Type-specific information about the file. In this case, it is the corresponding tablespace name for the datafile.
<file>.<incarnation>. A special number pair that ASM generates to insure uniqueness.