220-1101 Question 398
Single answer5.2 Given a scenario, troubleshoot drive and RAID issues.A small business file server uses a hardware RAID 1 array with two SATA drives. Users report the server is still accessible, but the administrator notices the RAID controller utility shows the array status as "degraded" and one drive has a solid amber fault LED. A replacement drive of the same capacity has arrived. Which of the following should the technician do NEXT to restore fault tolerance with the LEAST risk of data loss?
- A
Replace the failed drive with the new drive and allow the RAID controller to rebuild the mirror
- B
Back up the server, delete the degraded array, recreate RAID 1, and restore the data
- C
Replace both drives so the array has matching age and performance characteristics
- D
Convert the array to RAID 0 temporarily to improve performance until maintenance is complete
Show answer and explanation
Correct answer: A
Explanation
A degraded RAID 1 array means one mirrored disk has failed, but the array is still functioning from the remaining good disk. The appropriate response is to confirm the failed member, replace that drive with a supported replacement, and allow the controller to rebuild the array. This is consistent with common hardware RAID vendor guidance from manufacturers such as Dell PERC, HPE Smart Array, and Broadcom/LSI RAID controllers, which generally recommend replacing the failed disk and monitoring rebuild status rather than deleting and recreating the array. Although verifying backups before hardware changes is a sound best practice, the key corrective action to restore fault tolerance is replacing the failed drive and rebuilding the mirror.
- A. Correct.
Correct. In RAID 1, the system can continue operating on the surviving disk after one member fails. Best practice is to replace only the failed drive with a compatible drive of equal or greater usable capacity, then let the hardware RAID controller rebuild the mirror from the healthy member. This restores redundancy with minimal disruption and avoids unnecessary changes to a functioning array.
- B. Incorrect.
Incorrect. Deleting and recreating the array would destroy the RAID metadata and typically make the data inaccessible until restored from backup. While having a backup is important before performing disk work, deleting a degraded but still functional RAID 1 array is not the next step and creates unnecessary downtime and risk.
- C. Incorrect.
Incorrect. Replacing both drives is unnecessary and increases risk because the surviving drive currently contains the active data needed for the rebuild. Removing it could eliminate the only good copy in the array. Matching age is not a requirement for RAID 1 recovery; compatibility and capacity are the important factors.
- D. Incorrect.
Incorrect. RAID 0 provides striping with no redundancy and cannot be used as a safe temporary recovery method for a degraded mirror. Converting a live RAID 1 array to RAID 0 would not be an appropriate troubleshooting step and would increase the risk of total data loss.