Kfod don't find any griddisks.

Hi. I am trying to simulate exadata in virtual box for study purpose, but I am stuck in this stage.

I have two db nodes and two cell nodes. I have already created the griddisks as bellow on all cell nodes. This is a example of cell node 1:

[celladmin@exadatacell01 ~]$ cellcli -e list griddisk
     FLASH_PROD_FD_00_exadatacell01 active
     FLASH_PROD_FD_01_exadatacell01 active
     FLASH_PROD_FD_02_exadatacell01 active
     FLASH_PROD_FD_03_exadatacell01 active
     GRID_PROD_CD_01_exadatacell01  active
     GRID_PROD_CD_02_exadatacell01  active
     GRID_PROD_CD_03_exadatacell01  active
     GRID_PROD_CD_04_exadatacell01  active
     GRID_PROD_CD_05_exadatacell01  active
     GRID_PROD_CD_06_exadatacell01  active
     GRID_PROD_CD_07_exadatacell01  active
     GRID_PROD_CD_08_exadatacell01  active