asm drop disk

Hello,

Does one kown the role that must a user have to be able to administer asmdisks?

I am facing the issue not beeing able to drop a disk from diskgroup:

sqlplus / as sysdba;

select GROUP_NUMBER,NAME from V$ASM_DISKGROUP;

GROUP_NUMBER NAME

------------ ------------------------------

           1 XDATA_FDWH

           2 XFLASH_FDWH

SQL> select group_number, name, TOTAL_MB, FREE_MB from V$asm_disk_stat;

GROUP_NUMBER NAME                             TOTAL_MB    FREE_MB

------------ ------------------------------ ---------- ----------

           1              XDATA_FDWH_0021                    204828      22002

alter diskgroup XDATA_FDWH drop disk XDATA_FDWH_0021;

alter diskgroup XDATA_FDWH drop disk XDATA_FDWH_0021

*

ERROR at line 1:

ORA-15032: not all alterations performed