LFCS Storage Management Practice Question
Exhibit
Refer to the exhibit. # lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 20G 0 disk ├─sda1 8:1 0 1G 0 part /boot ├─sda2 8:2 0 10G 0 part / └─sda3 8:3 0 9G 0 part [SWAP] sdb 8:16 0 10G 0 disk └─sdb1 8:17 0 10G 0 part sdc 8:32 0 5G 0 disk └─sdc1 8:33 0 5G 0 part /data
Refer to the exhibit. The administrator wants to create a RAID 1 array using /dev/sdb1 and /dev/sdc1. Which command should be used?
⚠ Common exam trap
Many exam-takers confuse RAID levels and their minimum device requirements, often selecting RAID 5 or RAID 10 without verifying the device count, or mistakenly thinking RAID 0 provides redundancy.
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
✓
mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1
RAID 1 (mirroring) requires exactly two devices to provide redundancy by duplicating data across both disks. The `--level=1` parameter specifies RAID 1, and `--raid-devices=2` matches the two partitions /dev/sdb1 and /dev/sdc1.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
mdadm --create /dev/md0 --level=5 --raid-devices=2 /dev/sdb1 /dev/sdc1
Why it's wrong here
--level=5 configures RAID 5, which stripes data with distributed parity and requires at least three devices, so two disks cannot satisfy it. It is tempting because RAID 5 offers redundancy and capacity efficiency, making it a common default for arrays, but the scenario explicitly requires RAID 1 mirroring across exactly two partitions.
- ✓
mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1
Why this is correct
The `--create` mode with `--level=1` builds a RAID 1 mirror across exactly two member devices, satisfying the stem's redundancy requirement. Naming `/dev/sdb1` and `/dev/sdc1` after `--raid-devices=2` matches the declared count, so mdadm assembles `/dev/md0` without prompting for a missing or spare disk.
- ✗
mdadm --create /dev/md0 --level=10 --raid-devices=2 /dev/sdb1 /dev/sdc1
Why it's wrong here
--level=10 builds a nested RAID 1+0, which needs a minimum of four devices to form mirrored stripes. It is tempting because RAID 10 also provides mirroring plus performance, but with only two partitions mdadm cannot assemble the required stripe-and-mirror layout, so the command fails.
- ✗
mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sdb1 /dev/sdc1
Why it's wrong here
--level=0 creates striping with no redundancy, so a single disk failure destroys the array. It is tempting because RAID 0 uses both devices for capacity and speed, but the requirement is RAID 1, which mirrors identical data across /dev/sdb1 and /dev/sdc1 for fault tolerance.
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.