The answer is that the filesystem on the logical volume has not been resized after extending the LV. This is because `lvextend` only expands the block device itself, while the filesystem—whether ext4 or XFS—continues to see the original size until it is explicitly grown with `resize2fs` or `xfs_growfs`. The `df` command reports filesystem usage, not the underlying logical volume size, so when you see `lvextend not showing space` in `df`, it means you’ve missed this critical second step. On the LFCS exam, this is a classic trap: candidates extend the LV and immediately run `df`, expecting the new space to appear, but the filesystem resize is a separate, required operation. To remember, think of the logical volume as a container and the filesystem as the data inside—enlarging the container does not automatically fill it. A simple memory tip is “extend the LV, then grow the FS,” or for ext4, recall the mnemonic “resize2fs after lvextend.”
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.
# df -h /data
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_data-lv_data 100G 50G 50G 50% /data
# lvextend -L +10G /dev/mapper/vg_data-lv_data
Size of logical volume vg_data/lv_data changed from 100.00 GiB to 110.00 GiB.
Logical volume vg_data/lv_data successfully resized.
# df -h /data
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_data-lv_data 100G 50G 50G 50% /data
After extending the logical volume, the df output still shows 100G. What is the most likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The filesystem on the logical volume has not been resized.
Option A is correct because `lvextend` only increases the size of the logical volume at the block device level. The filesystem (e.g., ext4, XFS) still sees the original size until it is explicitly resized with a command like `resize2fs` (for ext4) or `xfs_growfs` (for XFS). The `df` command reports filesystem usage, not the underlying block device size, so the filesystem must be grown to match the LV.
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.
✓
The filesystem on the logical volume has not been resized.
Why this is correct
Need to run resize2fs or xfs_growfs.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
lvresize must be used instead of lvextend.
Why it's wrong here
lvextend is correct; lvresize is similar.
✗
The kernel has not detected the new size; reboot required.
Why it's wrong here
Kernel can detect changes without reboot.
✗
The mount point must be remounted with the 'remount' option.
Why it's wrong here
Remounting does not resize filesystem.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume extending the logical volume automatically resizes the filesystem, but the LFCS exam tests the explicit two-step process: LV extension followed by filesystem resize.
Trap categories for this question
Similar concept trap
lvextend is correct; lvresize is similar.
Detailed technical explanation
How to think about this question
Under the hood, LVM uses device-mapper to present the LV as a block device. When `lvextend` is run, the kernel updates the mapping table, making the extra space available to the block layer. However, the filesystem superblock still records the original size; tools like `resize2fs` or `xfs_growfs` update the superblock and inode tables to utilize the new space. In a real-world scenario, forgetting to run the filesystem resize after extending an LV is a common cause of 'no space left' alerts despite ample LV capacity.
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: The filesystem on the logical volume has not been resized. — Option A is correct because `lvextend` only increases the size of the logical volume at the block device level. The filesystem (e.g., ext4, XFS) still sees the original size until it is explicitly resized with a command like `resize2fs` (for ext4) or `xfs_growfs` (for XFS). The `df` command reports filesystem usage, not the underlying block device size, so the filesystem must be grown to match the LV.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.