In which situations will the ASM metadata backup help you recover the ASM disk in a disk
group? (Choose all that apply.)
A.
when one or more file directory paths are accidentally deleted from an ASM disk group
B.
when one of the disks in a disk group is accidentally unplugged
C.
when the data file on an ASM disk group gets corrupted
D.
when one or more disks in an ASM disk group are lost
A and D are correct:
http://www.oracle.com/technetwork/articles/sql/11g-asm-083478.html
Metadata Backup and Restore
Many people think of ASM as a database with its own storage. This is not at the case at all—ASM does not store data; the database does. The ASM instance, however, maintains metadata such as the diskgroup names, the disks in them, the directories, and so on. This metadata is stored in the disk headers.