SK0-005 security-disaster-recovery Practice Question
After an unexpected power outage, a server fails to boot and displays an error indicating a degraded RAID array. The server has a RAID 5 configuration with four disks. One disk has failed, but the hot spare did not automatically rebuild. The administrator needs to restore data availability as quickly as possible. Which action should the technician take FIRST?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Replace the failed disk and initiate a manual rebuild.
Option A is correct because replacing the failed disk and initiating a manual rebuild directly restores redundancy and availability using the existing parity data. Option B is wrong because the hot spare is not faulty; the rebuild did not trigger automatically, likely due to a configuration issue, and swapping it does not address the failed disk. Option C is wrong because while a bad battery or cache can cause rebuild failures, checking this is a later step; the immediate need is to replace the failed disk to restore redundancy. Option D is wrong because a backup restore is a last resort and may result in data loss; the array is degraded but still functional, so rebuilding is faster and less disruptive.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Replace the failed disk and initiate a manual rebuild.
Why this is correct
The failed disk is the root cause of degradation. Replacing it provides a healthy member for the array, and a manual rebuild can be forced to restore redundancy quickly.
- ✗
Restore the server from the latest backup.
Why it's wrong here
Restoring from backup should only be done if the array is unrecoverable. The array is degraded but still online; a rebuild is faster and preserves recent data.
- ✗
Check the RAID controller battery and cache.
Why it's wrong here
A faulty battery or cache can prevent automatic rebuilds, but it is a secondary consideration. The primary goal is to eliminate the failed disk to avoid data loss.
- ✗
Replace the hot spare with a new disk.
Why it's wrong here
The hot spare is functioning hardware; the problem is that the array did not automatically use it. Swapping the spare does not solve the underlying rebuild trigger issue.
Quick reference
RAID Level Comparison
| RAID Level | Min Disks | Fault Tolerance | Read | Write | Usable Capacity |
|---|---|---|---|---|---|
| RAID 0 | 2 | None | Excellent | Excellent | 100% |
| RAID 1 | 2 | 1 disk | Good | Moderate | 50% |
| RAID 5 | 3 | 1 disk | Good | Moderate | 67–94% |
| RAID 6 | 4 | 2 disks | Good | Lower | 50–88% |
| RAID 10 | 4 | 1 disk per mirror | Excellent | Good | 50% |
RAID is not a backup strategy — it protects against disk failure but not against accidental deletion, ransomware, or site-level events.
Go deeper
Related to this question
Learn chapter
Operating System Installation and Configuration
Key term
RAID 5
RAID 5 is a disk array configuration that uses block-level striping with distributed parity to provide fault tolerance and good read performance while using storage space efficiently.
Key term
RAID Levels
RAID (Redundant Array of Independent Disks) levels are different configurations that combine multiple hard drives or SSDs to improve performance, reliability, or both.
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Same concept, more angles
2 more ways this is tested on SK0-005
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is replacing a failed hard drive in a hot-swap RAID 5 array. After inserting the new drive, the RAID controller does not automatically rebuild. What should the technician do first?
hard- A.Check the SAS cable connection
- B.Reboot the server
- C.Replace the drive with a different model
- ✓ D.Manually initiate a rebuild from the RAID controller utility
Why D: Many RAID controllers require manual initiation of the rebuild process. Rebooting may not trigger it. Replacing with a different model is unnecessary. Checking cabling is less likely since the drive is detected. The technician should use the controller utility to start the rebuild.
Variation 2. A server has a RAID 5 array with four drives. One drive fails and is replaced. During the rebuild, a second drive reports a media error and the rebuild fails. What should the administrator do FIRST to minimize the risk of permanent data loss?
hard- A.Run a consistency check on the array
- B.Replace the drive that reported the media error immediately
- ✓ C.Back up all critical data before any further rebuilding
- D.Restart the RAID controller to reinitialize the rebuild
Why C: A media error on another drive during a RAID 5 rebuild indicates that drive may also be failing. If another drive fails completely, the entire array and its data will be lost. Therefore, the immediate priority is to back up critical data before any further rebuild action. Replacing the drive or restarting the controller could trigger another rebuild, risking complete array loss. A consistency check does not address the urgency.
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed July 2026 · checked against the official CompTIA exam blueprint
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