select
  fs_name,                                 -- FS_NAME VARCHAR2(1024)
  vol_device,                              -- VOL_DEVICE VARCHAR2(256)
  vol_label,                               -- VOL_LABEL VARCHAR2(64)
  primary_vol,                             -- PRIMARY_VOL VARCHAR2(5)
  total_mb,                                -- TOTAL_MB NUMBER
  free_mb                                  -- FREE_MB NUMBER
from
  gv$asm_acfsvolumes
where
  inst_id = USERENV('Instance')