LFCS Storage Management Practice Question
A system administrator is setting up a new backup server. The server has two 4TB disks /dev/sda and /dev/sdb. The administrator decides to create a RAID1 array and then an LVM volume group on top of the RAID device. After creating the RAID1 array /dev/md0, they create a physical volume, volume group named vg_backup, and a logical volume lv_data of size 2TB. Then they format with ext4 and mount at /backup. During testing, they realize that the backup data volume will likely exceed 2TB eventually. They want to expand the filesystem to use all available space in the RAID array. What is the correct procedure?
⚠ Common exam trap
LFCS often tests whether candidates know that ext4 can be resized online, so they might incorrectly choose to unmount first, which is unnecessary and causes downtime.
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
✓
lvextend -l +100%FREE /dev/vg_backup/lv_data, resize2fs /dev/vg_backup/lv_data.
The correct procedure is to extend the logical volume to use all remaining free space in the volume group with lvextend -l +100%FREE, then resize the ext4 filesystem online with resize2fs. Since ext4 supports online resizing, unmounting is not required.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
lvextend -l +100%FREE /dev/vg_backup/lv_data, resize2fs /dev/vg_backup/lv_data.
Why this is correct
Extending the logical volume with `lvextend -l +100%FREE` consumes all remaining free extents in vg_backup, which sits on the 4TB RAID1 array, so the LV grows to roughly 4TB. `resize2fs` then expands the ext4 filesystem online to match, satisfying the requirement to use all available space.
- ✗
Unmount /backup, lvextend -l +100%FREE /dev/vg_backup/lv_data, resize2fs /dev/vg_backup/lv_data, mount /backup.
Why it's wrong here
Unmounting is unnecessary for ext4 online growth, and this sequence omits pvresize, so the volume group still reports only the original 2TB and lvextend -l +100%FREE claims nothing. It would work only after pvresize had already extended the physical volume to cover the full RAID device.
- ✗
Create a new logical volume and mount it separately.
Why it's wrong here
A second logical volume splits storage into separate mount points rather than expanding /backup, so the existing filesystem still caps at 2TB. Creating additional volumes is correct for isolating data with distinct retention or performance needs, not for growing one filesystem into free space.
- ✗
Add new disk to RAID array, then extend LVM.
Why it's wrong here
Adding a disk to the RAID1 array grows /dev/md0, but the existing physical volume must then be resized with pvresize before the volume group sees the space; skipping that leaves vg_backup unchanged. Adding disks is correct when raw capacity is exhausted, not when unallocated space already exists.
Quick reference
RAID Level Comparison
| RAID Level | Min Disks | Fault Tolerance | Read | Write | Usable Capacity |
|---|---|---|---|---|---|
| RAID 0 | 2 | None | Excellent | Excellent | 100% |
| RAID 1 | 2 | 1 disk | Good | Moderate | 50% |
| RAID 5 | 3 | 1 disk | Good | Moderate | 67–94% |
| RAID 6 | 4 | 2 disks | Good | Lower | 50–88% |
| RAID 10 | 4 | 1 disk per mirror | Excellent | Good | 50% |
RAID is not a backup strategy — it protects against disk failure but not against accidental deletion, ransomware, or site-level events.
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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.