200-150 · Question #30
What is the minimum number of disks that are needed in RAID 1?
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
How the community answered
(26 responses)- A4% (1)
- B88% (23)
- C8% (2)
Why each option
RAID 1 is disk mirroring and requires exactly 2 disks at minimum, as each write is duplicated simultaneously to both disks to provide redundancy.
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.
RAID 1 works by writing identical data to two disks in parallel, so the absolute minimum is 2 disks. If one disk fails, the second contains a complete copy of all data and the system continues operating without data loss, making 2 the lowest possible count for any meaningful mirror configuration.
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.
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
Source: https://learn.microsoft.com/en-us/windows-server/storage/storage-spaces/storage-spaces-fault-tolerance
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