200-150 Question #30: Real Exam Question with Answer & Explanation

The correct answer is B: 2 disks. RAID 1 is disk mirroring and requires exactly 2 disks at minimum, as each write is duplicated simultaneously to both disks to provide redundancy.

Question

What is the minimum number of disks that are needed in RAID 1?

Options

A4 disks
B2 disks
C8 disks
D16 disks

Explanation

RAID 1 is disk mirroring and requires exactly 2 disks at minimum, as each write is duplicated simultaneously to both disks to provide redundancy.

Common mistakes.

A. 4 disks is the minimum required for RAID 10, which combines mirroring (RAID 1) and striping (RAID 0) across two mirrored pairs, not for basic RAID 1 mirroring.
C. 8 disks far exceeds the RAID 1 minimum requirement - a single mirror pair of 2 disks fully satisfies the RAID 1 definition regardless of capacity needs.
D. 16 disks has no basis as a RAID 1 minimum - RAID 1 achieves complete mirrored redundancy with just 2 disks and does not require any specific minimum beyond that.

Concept tested. RAID 1 disk mirroring minimum disk count

Reference. https://learn.microsoft.com/en-us/windows-server/storage/storage-spaces/storage-spaces-fault-tolerance

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