Question 34 of 511
Block Devices, Filesystems and Advanced StorageeasyMultiple ChoiceObjective-mapped

LPIC-2 Practice Question: Block Devices, Filesystems and Advanced Storage

This LPIC-2 practice question tests your understanding of block devices, filesystems and advanced storage. 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

# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4] 
md0 : active raid1 sdb1[0] sdc1[1]
      2097152 blocks [2/2] [UU]
      
unused devices: <none>

Refer to the exhibit. A system administrator wants to replace disk sdb1 in the RAID1 array. After physically removing sdb, which sequence of commands should be used?

Question 1easymultiple choice
Full question →

Exhibit

# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4] 
md0 : active raid1 sdb1[0] sdc1[1]
      2097152 blocks [2/2] [UU]
      
unused devices: <none>

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 /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1; mdadm --manage /dev/md0 --run

Option D is correct because after physically removing the failed disk (sdb), the administrator must first mark the device as failed using `--fail`, then remove it with `--remove`, add the new disk (sdd1) with `--add`, and finally run `--run` to ensure the array is activated if it was stopped or degraded. The `--run` flag is necessary because a RAID1 array with a missing device may not automatically start; this command forces the array to become active so the rebuild can begin.

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.

  • mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1

    Why it's wrong here

    Missing the --fail step; the device must be marked as failed first.

  • mdadm /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1

    Why it's wrong here

    Missing the --manage --run command to activate the new disk.

  • mdadm /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm --grow /dev/md0 --add /dev/sdd1; mdadm --manage /dev/md0 --run

    Why it's wrong here

    --grow is not needed for adding a replacement disk.

  • mdadm /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1; mdadm --manage /dev/md0 --run

    Why this is correct

    Proper sequence: fail, remove, add, run.

    Related concept

    Read the scenario before looking for a memorised answer.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often forget the `--run` step, assuming the array will automatically start after adding a new disk, or they mistakenly use `--grow` for adding a replacement disk instead of `--add`.

Trap categories for this question

  • Command / output trap

    Missing the --manage --run command to activate the new disk.

Detailed technical explanation

How to think about this question

Under the hood, `mdadm --fail` updates the superblock on the remaining devices to mark the failed disk as faulty, which is required before removal to maintain metadata consistency. The `--run` option is critical because md arrays can enter an 'inactive' state when a member is missing; without it, the array remains stopped and the new disk cannot be synchronized. In real-world scenarios, if a hot-swap backplane does not automatically trigger array reassembly, the `--run` flag ensures the array becomes active immediately after adding the replacement.

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 LPIC-2 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.

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FAQ

Questions learners often ask

What does this LPIC-2 question test?

Block Devices, Filesystems and Advanced Storage — This question tests Block Devices, Filesystems and Advanced Storage — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: mdadm /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1; mdadm --manage /dev/md0 --run — Option D is correct because after physically removing the failed disk (sdb), the administrator must first mark the device as failed using `--fail`, then remove it with `--remove`, add the new disk (sdd1) with `--add`, and finally run `--run` to ensure the array is activated if it was stopped or degraded. The `--run` flag is necessary because a RAID1 array with a missing device may not automatically start; this command forces the array to become active so the rebuild can begin.

What should I do if I get this LPIC-2 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 25, 2026

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This LPIC-2 practice question is part of Courseiva's free LPI 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 LPIC-2 exam.