单项选择题 HowcanyoureversetheeffectsofanALTERDISKGROUP...DROPDISKcommandifithasalreadycompleted？（）

单项选择题 Whichtypeofdatabasefileisspreadacrossalldisksinadiskgroup？（）

单项选择题 On the development database rac0， there are six raw devices： /dev/raw/raw1 through /dev/raw/raw6. /dev/raw/raw1 and /dev/raw/raw2 are 8GB each， and the rest are 6GB each. An existing disk group +DATA1， of NORMAL REDUNDANCY， uses /dev/raw/raw1 and /dev/raw/raw2.  Which series of the following commands will drop one of the failure groups for +DATA1， create a new disk group +DATA2 using two of the remaining four raw devices， and then cancel the drop operation from +DATA1？ （）