OCP-1Z0-053-V12.02-50题

 

50.Examine the following command:

ALTER DISKGROUP data MOUNT FORCE;

In which scenario can you use the above command to mount the disk group?

A. when ASM disk goes offline

B. when one or more ASM files are dropped

C. when some disks in a disk group are offline

D. when some disks in a failure group for a disk group are rebalancing

Answer: C

答案解析：

参考：http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_1007.htm#SQLRF52684

FORCE | NOFORCE Use these clauses to determine the circumstances under which the disk groups are mounted.

• In the FORCE mode, Oracle ASM attempts to mount the disk group even if it cannot discover all of the devices that belong to the disk group. This setting is useful if some of the disks in a normal or high redundancy disk group became unavailable while the disk group was dismounted. When MOUNT FORCEsucceeds, Oracle ASM takes the missing disks offline.--感觉这里应该为online？

  If Oracle ASM discovers all of the disks in the disk group, then MOUNT FORCE fails. Therefore, use the MOUNT FORCE setting only if some disks are unavailable. Otherwise, use NOFORCE.

  In normal- and high-redundancy disk groups, disks from one failure group can be unavailable and MOUNT FORCE will succeed. Also in high-redundancy disk groups, two disks in two different failure groups can be unavailable and MOUNT FORCE will succeed. Any other combination of unavailable disks causes the operation to fail, because Oracle ASM cannot guarantee that a valid copy of all user data or metadata exists on the available disks.

• In the NOFORCE mode, Oracle ASM does not attempt to mount the disk group unless it can discover all the member disks. This is the default.