171.After executing the command alter diskgroup disk group2 drop disk dg2a; you issue the following
command from the ASM instance:
Select group_number, count(*) from v$asm_operation;
What is the implication if the query against V$ASM_OPERATION returns zero rows?
A. The drop disk operation is still proceeding and you cannot yet run the undrop disks operation.
B. The drop disk operation is complete and you can run the undrop disks command if needed.
C. The drop disk operation is complete and you cannot run the undrop disk command.
D. The query will fail since there is not a V$ASM_OPERATION view available in an ASM instance.
E. None of the above is true.
Answer: C
答案解析：
参考：http://blog.csdn.net/rlhua/article/details/12972983
UNDROP命令仅对磁盘的暂挂删除操作起作用；它对于已经完成的删除操作没有影响。