655.Examine the following ALTER command:
SQL> ALTER DISKGROUP dgroup1 UNDROP DISKS;
What is the purpose of the command?
A. It cancels all pending disk drops within the disk group.
B. It restores disks that are being dropped as the result of a DROP DISKGROUP operation
C. It mounts disks in the disk group for which the drop-disk operation has already been co pleted
D. It restores all the dropped disks in the disk group for which the drop-disk operation has already been completed
E. It adds previously dropped disks back into the disk group
Answer: A
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_1007.htm#SQLRF55558
undrop_disk_clause
Use this clause to cancel the drop of disks from the disk group. You can cancel the pending drop of all the disks in one
or more disk groups (by specifyingdiskgroup_name) or of all the disks in all disk groups (by specifying ALL).
This clause is not relevant for disks that have already been completely dropped from the disk group or for disk groups that have been completely dropped. This clause results in a long-running operation. You can see the status
of the operation by querying the V$ASM_OPERATION dynamic performance view.
Undropping a Disk from a Disk Group: Example To cancel the drop of disks from a disk group, dgroup_01, issue the following statement: