CompTIA A+ Core 1 (220-1201)Hardware and Network TroubleshootingHard
A technician is troubleshooting a server with a RAID 5 array configured with five 2TB drives. The server is experiencing degraded performance, and the RAID controller reports that one drive has failed and another drive is showing predictive failure warnings. The technician needs to restore optimal performance and fault tolerance with minimal downtime. Which of the following actions should the technician take FIRST?
- AReplace the drive showing predictive failure warnings.
- BPower down the server and replace both drives simultaneously.
- CReplace the completely failed drive.
- DBack up all critical data from the RAID array.
Show answer & explanationAnswer & explanation
Correct answer: D. Back up all critical data from the RAID array.
When a RAID 5 array has one failed drive and another showing predictive failure, it is in a highly vulnerable state. If the second drive fails completely before recovery, all data will be lost. Therefore, the absolute first priority is to back up all critical data to ensure data integrity before attempting any drive replacements, which carry a risk of further failure during rebuild.
Why the other options are wrong
- A. Replacing the predictive failure drive first doesn't address the already failed drive, and the array is still vulnerable. It also risks further degradation during rebuild.
- B. Powering down the server and replacing both simultaneously is not ideal. A RAID 5 array can operate with one failed drive. Replacing both at once means a full rebuild of two drives, which is riskier than addressing them sequentially after a backup, or at least one at a time if hot-swappable.
- C. Replacing the completely failed drive first initiates a rebuild, which puts stress on the remaining drives, including the one with predictive failure. If that drive fails during the rebuild, data loss is inevitable.
RAID 5 Double-Fault Mitigation
The process of safely handling a RAID 5 array where one drive has failed and another is showing signs of impending failure, prioritizing data integrity.
- RAID 5 can only tolerate a single drive failure.
- Two failures mean complete data loss.
- Immediate data backup is crucial before attempting repairs.
Memory trick: When RAID 5 is one drive from disaster, backup first, then fix.