EX200 Configure local storage Practice Question
A RHEL 8 system has an ext4 filesystem on /dev/sdb1 mounted at /backup. The admin runs out of space and wants to extend the filesystem. He adds a new disk /dev/sdc, creates a partition /dev/sdc1 (all space), adds it to LVM by creating a PV and extending the VG that contains the LV for /backup. He then extends the logical volume with lvextend -L+20G /dev/vg_backup/lv_backup. The command succeeds, but the filesystem still shows the old size. What did he forget to do?
⚠ Common exam trap
Candidates often assume `lvextend` automatically resizes the filesystem, but it only extends the logical volume; a separate filesystem resize command is required for non-LVM-aware filesystems like 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
✓
Resize the filesystem using resize2fs.
When extending an LVM logical volume, the `lvextend` command only expands the logical volume's block device, not the filesystem residing on it. After extending the LV, the admin must run `resize2fs` (for ext4) to resize the filesystem to match the new LV size. Without this step, the kernel still sees the old filesystem metadata, so `df -h` reports the original size.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Reboot the system to recognize the new space.
Why it's wrong here
Rebooting would not change the fact that the ext4 superblock still records the original block count. The kernel and device-mapper driver have already recognized the enlarged logical volume the instant lvextend was issued, so a reboot just wastes time and causes downtime. Even after a reboot, the filesystem remains the old smaller size unless you explicitly run resize2fs to update its metadata.
- ✓
Resize the filesystem using resize2fs.
Why this is correct
Running resize2fs on the logical volume is the mandatory second step because lvextend only expands the block device, not the filesystem. The ext4 superblock's block count is still set to the old capacity, and the resize2fs utility updates the on-disk metadata and grows the filesystem to consume the newly available blocks. Because the filesystem is already mounted, the online resize can be done with no downtime, using the device path such as /dev/vg/lv.
- ✗
Run lvchange -ay to activate the logical volume.
Why it's wrong here
The logical volume is necessarily active already, since its filesystem is mounted and being used; lvchange -ay only affects inactive LVs and would return an error if you attempt to activate an already-active one. Activation is unrelated to the resize process, which only requires that the LV mapping be present. You can verify its active status with lvs or lvdisplay to see the 'a' state, but running lvchange -ay is redundant and does nothing to help the filesystem see new space.
- ✗
Unmount the filesystem before extending the LV.
Why it's wrong here
Unmounting is unnecessary and counterproductive because LVM and the kernel support online extension of both the logical volume and the ext4 filesystem while it is mounted. The entire resize procedure—lvextend followed by resize2fs—can be performed without interrupting access to the data. Forcing an unmount would require stopping processes and creating a maintenance window, which defeats the purpose of LVM's online resizing capability and is not part of the correct procedure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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