The correct command is mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1, because RAID 1, or mirroring, duplicates data across exactly two devices to provide fault tolerance, and the --level=1 parameter specifies this redundancy while --raid-devices=2 matches the two partitions listed. On the Linux Foundation Certified System Administrator LFCS exam, this tests your ability to build software RAID arrays using mdadm, a common performance and reliability task. A frequent trap is forgetting that RAID 1 requires exactly two devices—using --raid-devices=3 or omitting the device list will fail. To remember, think of a mirror: it needs two surfaces to reflect data perfectly, so always pair --level=1 with two devices.
LFCS Storage Management Practice Question
This LFCS practice question tests your understanding of storage management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Option B is correct because 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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates 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.
Detailed technical explanation
How to think about this question
RAID 1 works by writing identical data to both member disks, so if one disk fails, the array remains operational using the mirror. Under the hood, mdadm uses a metadata superblock (version 1.0, 1.1, or 1.2 by default) to track array membership and state. In real-world scenarios, RAID 1 is often used for boot partitions or critical system data where read performance is improved (reads can be serviced from either disk) but write performance is limited to the slower disk.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Storage Management — This question tests Storage Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1 — Option B is correct because 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.
What should I do if I get this LFCS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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