RAID Level Supporting Fault Tolerance

A.

The RAID (Redundant Array of Independent Disks) is a data storage technology that combines multiple physical hard drives into a single logical unit to improve data redundancy, performance, and fault tolerance.

There are several RAID levels, each with different characteristics, such as data protection, performance, capacity, and cost.

The RAID levels that support fault tolerance use a technique called "parity" to recover data in case of a disk failure. Parity is a mathematical function that calculates the XOR (exclusive OR) value of the data bits on a set of disks and writes the result to another disk. If a disk fails, the data on that disk can be reconstructed using the parity information and data from the remaining disks.

Now, to answer the question, the RAID level that supports fault tolerance by writing parity to only one drive in the array is RAID 5. In RAID 5, the parity data is distributed across all the drives in the array except for one. This means that if one drive fails, the data can be reconstructed from the remaining drives and the parity information on the missing drive.

RAID 3 also uses parity for fault tolerance, but it writes the parity data to a dedicated parity drive, which can be a bottleneck for performance. RAID 6 uses two parity drives, which increases fault tolerance but also reduces usable capacity. RAID 10, on the other hand, uses a combination of mirroring and striping to provide fault tolerance, but it requires a minimum of four drives and has higher cost than other RAID levels.