What is the cause of the error?
A. The ASM_DISKGROUPS parameter is configured for three disk groups:DGROUP1,DGROUP2,and DGROUP3.
The underlying disks for these disk groups have apparently been lost.
B. The format of the ASM_DISKGROUPS parameter is incorrect. It should reference the disk group numbers,not the names of the disk groups
C. The ASM_POWER_LIMIT parameter is incorrectly set to 1.It should be set to the number of disk groups being attached to the ASM instance.
D. The ASM_DISKSTRING parameter is not set;therefore disk discovery is not possible.
E. There is insufficient information to solve this problem.
答案：（D）
解析：
查看ORA-15063异常
ORA-15063: ASM discovered an insufficient number of disks for diskgroup "string" Cause: ASM was unable to find a sufficient number of disks belonging to the diskgroup to continue the operation.
Action: Check that the disks in the diskgroup are present and functioning, that the owner of the ORACLE binary has read/write permission to the disks,
and that the ASM_DISKSTRING initialization parameter has been set correctly.
Verify that ASM discovers the appropriate disks by querying V$ASM_DISK from the ASM instance.