The correct answer is to use pvmove to move physical extents to another disk, then remove the old disk. This is because pvmove relocates data from the failing disk’s physical extents to another physical volume within the same volume group while the filesystem remains online and fully accessible, allowing you to replace a failing LVM disk without downtime. On the LFCS exam, this question tests your understanding of LVM’s online data migration capabilities, often appearing as a scenario where you must choose between unmounting, using dd, or pvmove; the common trap is assuming you need to take the volume offline first. Remember that pvmove works at the physical extent level, not the block level, so it preserves LVM metadata and avoids filesystem corruption. A helpful memory tip: “pvmove pivots data without pausing production.”
LFCS Storage Management Practice Question
This LFCS practice question tests your understanding of storage management. 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.
A system administrator receives an alert that disk /dev/sda is predicted to fail soon. The server uses LVM, and /dev/sda is part of a volume group named vg_system. Which of the following is the best course of action to replace the failing disk without downtime?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use pvmove to move physical extents to another disk, then remove the old disk.
Option D is correct because pvmove relocates physical extents from /dev/sda to another physical volume in the same volume group while the filesystem remains online and accessible. This allows the failing disk to be removed from vg_system without any downtime, preserving LVM metadata and data integrity.
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.
✗
Use dd to clone /dev/sda to a new disk and then replace.
Why it's wrong here
dd may cause downtime and I/O errors.
✗
Use ddrescue to copy data, then replace the disk.
Why it's wrong here
ddrescue is for failing disks but does not handle LVM metadata well.
✗
Remove /dev/sda from the volume group and add a new disk.
Why it's wrong here
Removing without moving data first causes loss.
✓
Use pvmove to move physical extents to another disk, then remove the old disk.
Why this is correct
pvmove safely relocates data online.
Clue confirmation
The clue word "best" in the question point toward this answer.
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 confuse block-level cloning (dd) with LVM-aware migration (pvmove), assuming any copy tool can replace a disk in an LVM setup without understanding that LVM metadata and extent mapping must be handled correctly to avoid downtime or data corruption.
Detailed technical explanation
How to think about this question
pvmove works by reading each physical extent from the source PV and writing it to a destination PV within the same VG, updating the LVM metadata atomically after each extent is moved. This operation is transparent to the filesystem layer because LVM remaps logical-to-physical extent mappings on the fly. In a real-world scenario, pvmove can be run in the background with 'pvmove -b' to avoid blocking I/O, and the system remains fully operational throughout the migration.
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: Use pvmove to move physical extents to another disk, then remove the old disk. — Option D is correct because pvmove relocates physical extents from /dev/sda to another physical volume in the same volume group while the filesystem remains online and accessible. This allows the failing disk to be removed from vg_system without any downtime, preserving LVM metadata and data integrity.
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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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