ASM - Create Diskgroup

ORACLE_SID=+ASM

sqlplus /as sysasm

To see only candidate disk

column path format  a40

Select PATH,GROUP_NUMBER,DISK_NUMBER,MOUNT_Status, HEADER_STATUS, TOTAL_MB, create_date

  from v$asm_disk

where header_status='CANDIDATE'

order by path;

To check kind of redundation 

SELECT TYPE, NAME FROM v$asm_diskgroup;

To see information about disk 

select GROUP_NUMBER,DISK_NUMBER,PATH,NAME,FAILGROUP,MOUNT_STATUS,HEADER_STATUS,STATE,TOTAL_MB,FREE_MB from v$asm_disk;

select GROUP_NUMBER,NAME,BLOCK_SIZE,STATE,TYPE,TOTAL_MB,FREE_MB,USABLE_FILE_MB,REQUIRED_MIRROR_FREE_MB,OFFLINE_DISKS,COMPATIBILITY, DATABASE_COMPATIBILITY from v$asm_diskgroup;

Create Diskgroup as external 

create diskgroup DATA_GRUP external redundancy disk

'/dev/sdm1','/dev/sdn1','/dev/sdo1';