LFCS Storage Management Practice Question
A system administrator needs to set up software RAID1 on a server for /data. The available disks are /dev/sdb (500GB) and /dev/sdc (1TB). What is the maximum usable capacity of the RAID1 array?
⚠ Common exam trap
Watch out — candidates often assume RAID1 adds capacities (like RAID0) or averages them, rather than recognizing that mirroring strictly limits usable space to the smallest disk's capacity.
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
✓
500GB
RAID1 (mirroring) writes identical data to all disks in the array, so the usable capacity is limited by the smallest disk. With /dev/sdb at 500GB and /dev/sdc at 1TB, the maximum usable capacity is 500GB. The remaining space on /dev/sdc (500GB) is unusable in the RAID1 array because it cannot be mirrored.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
500GB
Why this is correct
Correct: RAID1 uses only the smallest disk's capacity for data.
- ✗
250GB
Why it's wrong here
Incorrect; RAID1 does not halve capacity.
- ✗
1TB
Why it's wrong here
RAID1 capacity is the size of the smallest disk.
- ✗
1.5TB
Why it's wrong here
RAID1 mirrors, does not combine capacity.
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.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LFCS practice question is part of Courseiva's free Linux Foundation certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LFCS exam.