QUESTION 176
How can you reverse the effects of an ALTER DISKGROUP ... DROP DISK command if it has already
completed?
A. Issue the ALTER DISKGROUP ... ADD DISK command.
B. Issue the ALTER DISKGROUP ... UNDROP DISKS command.
C. Issue the ALTER DISKGROUP ... DROP DISK CANCEL command.
D. Retrieve the disk from the Recycle Bin after the operation completes.
Answer: A
同539题：http://blog.csdn.net/rlhua/article/details/15020285
对比534题：http://blog.csdn.net/rlhua/article/details/15020571
Explanation/Reference:
Section: Database Architecture & Resource Management, RAC, ASM
Use the undrop_disk_clause cancel the drop of disks from the disk group. 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.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_1006.htm#i2168780
Use the CREATE DISKGROUPclause to create a collection of disks.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_5008.htm
Use the add_disk_clause to add one or more disks to the disk group and specify attributes for the newly
added disk.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_1006.htm#i2168780