Question 512 of 527
Configure local storagehardMultiple ChoiceObjective-mapped

EX200 Configure local storage Practice Question

This EX200 practice question tests your understanding of configure local storage. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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

Personalities : [raid1] [raid0] [raid10] 
md0 : active raid1 sdb1[1] sda1[0]
      10485760 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

Refer to the exhibit. The /proc/mdstat output shows a RAID1 array with two devices. One of the disks (/dev/sda1) fails. Which sequence of commands would be used to remove the failed disk and add a new replacement disk /dev/sdc1?

Question 1hardmultiple choice
Full question →

Exhibit

Personalities : [raid1] [raid0] [raid10] 
md0 : active raid1 sdb1[1] sda1[0]
      10485760 blocks super 1.2 [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/sda1; mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1

Option B is correct because it uses the proper mdadm syntax with the device name immediately after the command, followed by the action and the disk. The --fail flag marks the disk as faulty, --remove removes it from the array, and --add adds the new replacement disk. This sequence ensures the array remains in a degraded state before safely replacing the failed component.

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 --fail /dev/md0 /dev/sda1; mdadm --remove /dev/md0 /dev/sda1; mdadm --add /dev/md0 /dev/sdc1

    Why it's wrong here

    Incorrect. The arguments order is wrong; the array device should come before the component.

  • mdadm /dev/md0 --fail /dev/sda1; mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1

    Why this is correct

    Correct. This is the proper sequence to replace a failed disk.

    Related concept

    Read the scenario before looking for a memorised answer.

  • mdadm /dev/md0 --set-faulty /dev/sda1; mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1

    Why it's wrong here

    Incorrect. --set-faulty is not a valid option; use --fail.

  • mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1

    Why it's wrong here

    Incorrect. The --fail step is omitted; the array may still consider the disk as active and refuse removal.

  • mdadm /dev/md0 --replace /dev/sda1 --with /dev/sdc1

    Why it's wrong here

    Incorrect. --replace is not a standard mdadm option.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Red Hat often tests the exact command syntax and flag order, and the trap here is that candidates confuse the valid flags (--fail vs --set-faulty) or assume --remove can be used directly without first marking the disk as failed.

Detailed technical explanation

How to think about this question

Under the hood, mdadm manages RAID arrays through the MD (Multiple Device) driver in the Linux kernel. The --fail action writes a 'Faulty' state to the superblock, causing the kernel to stop I/O to that device and reconstruct data from the remaining mirror. The --remove action then detaches the device from the array, and --add triggers a full resync of the new disk. In real-world scenarios, failing the disk first is critical to prevent data corruption if the disk is intermittently failing.

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 EX200 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 EX200 question test?

Configure local storage — This question tests Configure local 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/sda1; mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1 — Option B is correct because it uses the proper mdadm syntax with the device name immediately after the command, followed by the action and the disk. The --fail flag marks the disk as faulty, --remove removes it from the array, and --add adds the new replacement disk. This sequence ensures the array remains in a degraded state before safely replacing the failed component.

What should I do if I get this EX200 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 30, 2026

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