SELECT
name AS dg_name,
ROUND(total_mb / DECODE(TYPE, 'NORMAL', 2, 'HIGH', 3, 'EXTERN', 1)*1024*1024) AS size_byte,
ROUND(usable_file_mb*1024*1024 ) AS free_size_byte,
ROUND(100-(usable_file_mb /(total_mb / DECODE(TYPE, 'NORMAL', 2, 'HIGH', 3, 'EXTERN', 1)))* 100, 2) AS used_percent
FROM v$asm_diskgroup ;