RAID 1+0: The Optimistic Combination of Mirrors and Stripes

What level of RAID is known as a "stripe of mirrors"?

A. RAID 1+0

B. RAID 0+1

C. RAID 0

D. RAID 1

RAID 1+0: The Perfect Marriage of Performance and Redundancy

RAID 1+0, or RAID 10, is the RAID level known as a "stripe of mirrors," which combines the benefits of RAID 1 (mirroring) and RAID 0 (striping) to provide both performance and redundancy. It is often used in systems where both high availability and fault tolerance are critical, such as database and high-traffic web servers.

Explanation:

The level of RAID referred to as a "stripe of mirrors" is RAID 1+0, also known as RAID 10. This configuration combines the mirroring of RAID 1 with the striping of RAID 0. Essentially, RAID 10 writes data to a pair of drives to mirror them (RAID 1) and then the sets of mirrored drives are striped together (RAID 0). This offers the benefits of both performance enhancement (due to striping) and data redundancy (due to mirroring).

RAID 1+0 is often chosen for environments where both data redundancy and performance are critical. For example, it is commonly used in database servers, high-traffic web servers, and any application requiring high availability and fault tolerance. While RAID 1+0 does require a minimum of four disks, it is highly fault-tolerant and can withstand multiple simultaneous drive failures, as long as no mirrored pairs lose both of their drives.

It is important not to confuse RAID 1+0 with RAID 0+1, as they implement mirroring and striping in different orders. RAID 0+1 creates a striped set first (RAID 0), and then mirrors that set (RAID 1), making it less robust in comparison, as the failure of a single drive in one of the striped sets can cause the loss of the entire array.