LFCS Storage Management Practice Question
A Linux server uses LVM for its data volume /dev/vg_data/lv_app. The volume group vg_data has 30 GB of free extents and the logical volume lv_app is currently 100 GB. An administrator runs `lvextend -L +20G /dev/vg_data/lv_app` and receives a success message, but `df -h /app` still reports 100 GB. The filesystem on lv_app is ext4. Which command must the administrator run next to make the additional space usable?
⚠ Common exam trap
The trap here is assuming lvextend also resizes the filesystem, when in fact the filesystem must be grown separately for ext4.
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
✓
resize2fs /dev/vg_data/lv_app
Extending an LVM logical volume with lvextend changes only the block device mapping; the ext4 filesystem inside keeps its original size until resized. Running resize2fs against the LV path grows the filesystem online to fill the new extents, after which df reflects the additional capacity. The XFS-only grow tool, a consistency checker, and a PV-level resize command all fail to accomplish this here.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
e2fsck -f /dev/vg_data/lv_app
Why it's wrong here
e2fsck performs filesystem consistency checking, not resizing; it inspects and repairs metadata but never expands the addressable block count. Running it forces a check but leaves the filesystem at 100 GB, so df would still show the old size. It is only a prerequisite step before shrinking, not growing, an ext4 filesystem.
- ✓
resize2fs /dev/vg_data/lv_app
Why this is correct
The ext4 filesystem must be grown to match the enlarged block device; resize2fs performs that online growth without unmounting. lvextend only resizes the logical volume, so df still reports the old filesystem size until resize2fs runs. This is the standard two-step procedure for ext4 on LVM without the -r shortcut.
- ✗
xfs_growfs /app
Why it's wrong here
xfs_growfs works only on XFS filesystems and would immediately fail with an error like 'not a mounted XFS filesystem' against an ext4 volume. The scenario explicitly states the filesystem is ext4, so the XFS-specific growth tool is irrelevant. Choosing it confuses the two filesystem families and would leave the volume unchanged.
- ✗
pvresize /dev/vg_data/lv_app
Why it's wrong here
pvresize operates on physical volumes such as /dev/sdb, not logical volumes, and it adjusts the PV size recorded in LVM metadata. /dev/vg_data/lv_app is an LV path, so pvresize would reject it as not a physical volume. Even on a correct PV it would not grow the ext4 filesystem.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Linux Foundation exam blueprint
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.