A server administrator wants to ensure a storage array can survive the failure of two drives without the loss of dat a. Which of the following RAID levels should the administrator choose?

RAID 6 (Redundant Array of Independent Disks Level 6) is the appropriate choice as it is specifically designed to provide fault tolerance against the failure of up to two drives. It achieves this by implementing two independent parity blocks, often referred to as dual parity, which are distributed across all the drives in the array. This dual-parity scheme allows the array to reconstruct the data from two failed drives, ensuring data availability and integrity, which directly meets the administrator's requirement.

A. 0: RAID 0 (striping) offers no fault tolerance. The failure of a single drive will result in the loss of all data in the array.
B. 1: RAID 1 (mirroring) can only tolerate the failure of a single drive within a mirrored pair. It does not protect against two simultaneous drive failures.
C. 5: RAID 5 (striping with distributed parity) uses a single parity block and can only tolerate the failure of one drive.

1. Arpaci-Dusseau

R. H.

& Arpaci-Dusseau

A. C. (2018). Operating Systems: Three Easy Pieces. Arpaci-Dusseau Books. In Chapter 39

"Redundant Arrays of Inexpensive Disks (RAIDs)"

Section 39.6

"Other RAIDs"

it is stated: "RAID-6 can tolerate two disk failures and does so by using a more sophisticated parity scheme." (p. 10). Available from the University of Wisconsin-Madison: https://pages.cs.wisc.edu/~remzi/OSTEP/

2. Dell Inc. (2023). Dell PowerEdge RAID Controller 11 User's Guide. In the "RAID levels" section

the description for RAID 6 states: "RAID 6 provides data redundancy by using two parity blocks for each stripe. [...] RAID 6 supports the failure of up to two member disks in a virtual disk." (p. 21).

3. Storage Networking Industry Association (SNIA). (n.d.). SNIA Dictionary. Retrieved from https://www.snia.org/education/online-dictionary. The entry for "RAID Level 6" defines it as: "A form of RAID that uses two independent sets of parity for additional data protection. RAID 6 can survive the failure of two disks in an array."