How many disks should you identify?

You have a Windows 8.1 Enterprise client computer named Computer1. The Storage Spaces
settings of Computer1 are configured as shown in the following exhibit. (Click the Exhibit button.)

You plan to create a three-way mirror storage space in the storage pool and to set the size of the
storage space to 50 GB. You need to identify the minimum number of disks that must be added to
the storage pool for the planned mirror. How many disks should you identify?

A.
1

B.
3

C.
4

D.
5

Explanation:
In Windows Server 2012 Storage Spaces and Windows 8Storage Spaces, a 2-way mirror requires
at least 2 physical disks.
However, a 3-way mirror requires at least 5 physical disks.
The reason is that a 3-way mirror uses a quorum. In order to keep running, the mirror space must
keep over 50% of the disks functioning.
So a 3-way mirror must have at least 5 physical disks to be able to survive the loss of up to 2
physical disks.