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 receives an alert that the /var/log partition is 95% full. The partition is an LVM logical volume. The volume group has available free extents. Which of the following is the most efficient method to increase the size of the filesystem to 120GB (from current 100GB) without unmounting it?
lvextend -L 20G /dev/vg/log; resize2fs /dev/vg/log
Why wrong: Sets to 20G, not +20G.
lvextend -L +20G /dev/vg/log; xfs_growfs /data
Why wrong: xfs_growfs is for XFS, not ext4.
lvextend -L +20G /dev/vg/log; resize2fs /dev/vg/log
Correct: adds 20G to current size.
lvextend -L 120G /dev/vg/log; resize2fs /dev/vg/log
Why wrong: Sets absolute 120G, but if current is 100G, that works, but using + is safer.
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 +20G /dev/vg/log; resize2fs /dev/vg/log
Option C is correct because the partition is an LVM logical volume with an ext4 filesystem (implied by the use of resize2fs). The `lvextend -L +20G` command adds 20GB to the existing 100GB volume, making it 120GB, and `resize2fs /dev/vg/log` resizes the ext4 filesystem online without unmounting. This is the most efficient method as it uses relative sizing and the correct filesystem-specific resize tool.
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.
lvextend -L 20G /dev/vg/log; resize2fs /dev/vg/log
Why it's wrong here
Sets to 20G, not +20G.
lvextend -L +20G /dev/vg/log; xfs_growfs /data
Why it's wrong here
xfs_growfs is for XFS, not ext4.
lvextend -L +20G /dev/vg/log; resize2fs /dev/vg/log
Why this is correct
Correct: adds 20G to current size.
Related concept
Read the scenario before looking for a memorised answer.
lvextend -L 120G /dev/vg/log; resize2fs /dev/vg/log
Why it's wrong here
Sets absolute 120G, but if current is 100G, that works, but using + is safer.
Common exam traps
The trap here is that candidates confuse the absolute size flag `-L 120G` with the relative size flag `-L +20G`, or they incorrectly pair `xfs_growfs` with an ext4 filesystem, assuming all Linux filesystems use the same resize command.
Detailed technical explanation
Under the hood, `lvextend -L +20G` extends the logical volume by exactly 20GB using free extents from the volume group, and `resize2fs` then expands the ext4 superblock and block group descriptors to utilize the new space without requiring unmounting. A subtle behavior is that for ext4, `resize2fs` can only grow a mounted filesystem; shrinking requires unmounting. In real-world scenarios, administrators often use `-L +` to avoid typos when calculating absolute sizes, especially in automated scripts.
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 +20G /dev/vg/log; resize2fs /dev/vg/log — Option C is correct because the partition is an LVM logical volume with an ext4 filesystem (implied by the use of resize2fs). The `lvextend -L +20G` command adds 20GB to the existing 100GB volume, making it 120GB, and `resize2fs /dev/vg/log` resizes the ext4 filesystem online without unmounting. This is the most efficient method as it uses relative sizing and the correct filesystem-specific resize tool.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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