RAID 10 vs RAID 01: Differences and Fault Tolerance

RAID 10 and RAID 01 differ primarily in their fault tolerance and structure, although they offer similar performance and usable storage capacity.

• Structure:

  • RAID 10 (1+0) is created by first mirroring pairs of disks (RAID 1) and then striping across these mirrored pairs (RAID 0).
  • RAID 01 (0+1) is created by first striping data across disks (RAID 0) and then mirroring the entire striped set (RAID 1).

• Fault Tolerance:

  • RAID 10 offers better fault tolerance. It can survive multiple disk failures as long as no mirrored pair loses both disks. For example, if one disk fails in each mirrored pair, the array remains operational.
  • RAID 01 is less fault-tolerant. If a single disk fails in one striped set, that entire set fails, and if any disk in the mirrored set fails, the whole array fails. This means RAID 01 is more vulnerable to data loss with multiple disk failures.

• Performance and Capacity:

  • Both RAID 10 and RAID 01 provide similar read/write speeds and usable storage capacity (about half the total raw disk capacity due to mirroring).

• Rebuild and Reliability:

  • RAID 10 is simpler to rebuild and more reliable because failures are isolated to mirrored pairs.
  • RAID 01 can suffer from data loss if the array continues to run with a failed disk for a long time, increasing the risk of data divergence and unrecoverable data.

In summary, RAID 10 is generally preferred over RAID 01 due to its superior fault tolerance and reliability, while both offer comparable speed and storage efficiency.