220-1101 Question 381
Single answerAvailabilityA small medical office has a single file server that stores scheduling and billing data. The office manager says staff cannot lose access to these files during a single drive failure because appointments continue all day. The server has four identical hard drives and a hardware RAID controller. The manager also wants usable storage to remain as high as possible. Which RAID level should the technician recommend to best meet the availability requirement?
- A
RAID 0
- B
RAID 1
- C
RAID 5
- D
JBOD
Show answer and explanation
Correct answer: C
Explanation
The best answer is RAID 5 because the scenario specifically emphasizes availability during a single drive failure and also asks for the highest practical usable storage. In CompTIA A+ Core 1 objectives, availability is commonly tested through RAID concepts and fault-tolerant storage choices. RAID 5 is designed to survive one disk failure while continuing operation, making it a practical solution for small business file servers where uptime matters. RAID 1 also provides redundancy, but it is less storage-efficient. RAID 0 and JBOD do not provide the fault tolerance needed for continued access. This aligns with common vendor and industry documentation for RAID implementations: RAID 0 offers performance only, RAID 1 offers mirroring, and RAID 5 offers single-drive fault tolerance with distributed parity.
- A. Incorrect.
RAID 0 stripes data across multiple drives for performance and capacity, but it provides no fault tolerance. If any one drive fails, the entire array becomes unavailable. Someone might choose RAID 0 because it maximizes storage and speed, but it does not meet the office's requirement for continued access during a single drive failure.
- B. Incorrect.
RAID 1 mirrors data, so it does provide high availability during a single drive failure. However, with four identical drives, RAID 1 does not offer the best balance of availability and usable capacity for this scenario. A candidate might pick RAID 1 because it is well known for redundancy, but it sacrifices 50% of total raw storage and is less efficient than RAID 5 when the goal is to keep storage as high as possible while tolerating one failed drive.
- C. Correct.
RAID 5 uses block-level striping with distributed parity and requires at least three drives. It allows the array to remain operational if one drive fails, which satisfies the availability requirement. It also provides better usable capacity than RAID 1 because only the equivalent of one drive is used for parity across the array. With four identical drives, RAID 5 is the best choice here for maintaining access during a single drive failure while maximizing available storage.
- D. Incorrect.
JBOD combines drives without parity or mirroring. Depending on implementation, it may simply present disks individually or concatenate them into one volume, but it does not provide fault tolerance. A technician might confuse JBOD with RAID because both involve multiple disks, but JBOD does not ensure availability after a drive failure.