Quick Answer
The correct command is `lvextend -L +5G /dev/vg_data/lv_data`, which directly adds 5GB of capacity to the existing logical volume by using the `-L` flag with a plus sign to specify the exact size increase. This works because the volume group `vg_data` already has free physical extents available, meaning no new physical volumes need to be added before the extension can proceed. On the Linux Foundation Certified System Administrator LFCS exam, this question tests your understanding of logical volume management (LVM) resizing operations, a core skill for managing storage on enterprise Linux systems. A common trap is confusing the `-L` flag (which sets or adds to the size) with the `-l` flag (which uses extents instead of bytes), or forgetting the plus sign, which would set the volume to exactly 5GB rather than adding 5GB. To remember the syntax, think of the plus sign as “add to what’s already there”—without it, you’re overwriting, not extending.
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.
An administrator wants to extend a logical volume named 'lv_data' in volume group 'vg_data' by 5GB. The volume group has free physical extents. 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.
pvextend -L +5G /dev/vg_data/lv_data
Why wrong: pvextend is for physical volumes, not logical volumes.
lvextend -L +5G /dev/vg_data/lv_data
The + sign indicates adding space.
lvresize -L +5G /dev/vg_data/lv_data
Why wrong: lvresize is not a standard command.
lvextend -L 5G /dev/vg_data/lv_data
Why wrong: This sets the size to 5GB, not extends by 5GB.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
lvextend -L +5G /dev/vg_data/lv_data
The correct command to extend a logical volume is `lvextend`. Option B uses the correct syntax with the `-L +5G` flag, which adds 5GB to the existing logical volume `/dev/vg_data/lv_data`. The volume group `vg_data` has free physical extents, so the extension can proceed without needing to add new physical volumes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
pvextend -L +5G /dev/vg_data/lv_data
Why it's wrong here
pvextend is for physical volumes, not logical volumes.
lvextend -L +5G /dev/vg_data/lv_data
Why this is correct
The + sign indicates adding space.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
lvresize -L +5G /dev/vg_data/lv_data
Why it's wrong here
lvresize is not a standard command.
lvextend -L 5G /dev/vg_data/lv_data
Why it's wrong here
This sets the size to 5GB, not extends by 5GB.
Common exam traps
The trap here is that candidates may confuse `lvextend` with `lvresize` or forget the `+` sign in the size specification, leading them to choose Option C or D, or they might incorrectly use `pvextend` (Option A) which does not exist in LVM.
Trap categories for this question
Command / output trap
lvresize is not a standard command.
Detailed technical explanation
Under the hood, `lvextend` allocates free physical extents (PEs) from the volume group to the logical volume. The size of a PE is typically 4MB by default, so extending by 5GB requires allocating 1280 PEs (5GB / 4MB). After extending the logical volume, the filesystem must be resized separately using `resize2fs` (for ext4) or `xfs_growfs` (for XFS) unless the `-r` flag is used with `lvextend` to automate this. In real-world scenarios, forgetting to resize the filesystem after extending the logical volume is a common mistake that leads to no usable additional space.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Storage Management — This question tests Storage Management — Read the scenario before looking for a memorised answer..
The correct answer is: lvextend -L +5G /dev/vg_data/lv_data — The correct command to extend a logical volume is `lvextend`. Option B uses the correct syntax with the `-L +5G` flag, which adds 5GB to the existing logical volume `/dev/vg_data/lv_data`. The volume group `vg_data` has free physical extents, so the extension can proceed without needing to add new physical volumes.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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