LFCS Storage Management Practice Question
A Linux server has a volume group named vg_data that currently contains two physical volumes. The administrator needs to remove /dev/sdb1 from vg_data, but pvremove /dev/sdb1 returns an error stating the physical volume is still in use. Which command should the administrator run FIRST to migrate the extents off /dev/sdb1 onto the remaining physical volume?
⚠ Common exam trap
The trap here is assuming that vgreduce or pvremove automatically evacuates data, when in fact LVM requires pvmove to migrate extents before a PV can be detached.
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
✓
pvmove /dev/sdb1
To safely remove a physical volume from an active volume group, the allocated extents must first be moved to other PVs. pvmove performs this online migration without unmounting filesystems. Only after the PV reports zero used extents can vgreduce detach it and pvremove clear its label. Attempting vgreduce or pvremove beforehand fails because LVM protects allocated data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
lvconvert --repair vg_data
Why it's wrong here
lvconvert --repair is used to repair a RAID logical volume by replacing a failed device, not to migrate extents off a physical volume. It does not move data from /dev/sdb1 to another PV, so it will not resolve the 'PV in use' error. The scenario requires extent relocation, which is handled by pvmove.
- ✗
vgreduce vg_data /dev/sdb1
Why it's wrong here
vgreduce removes a physical volume from a volume group, but it refuses to complete when the PV still has allocated logical extents. Because /dev/sdb1 is still in use, vgreduce will fail with an error about the PV containing data. The extents must be relocated with pvmove before vgreduce can succeed.
- ✗
pvremove /dev/sdb1 --force
Why it's wrong here
pvremove erases the LVM label and metadata from a physical volume so the device is no longer recognized as a PV. Using --force does not relocate live extents; it simply strips the label, potentially making the data on that PV unreachable and corrupting the volume group. This is dangerous and not the correct first step.
- ✓
pvmove /dev/sdb1
Why this is correct
pvmove relocates all logical extents from the specified physical volume to other physical volumes in the same volume group while the logical volumes remain online. Once the extents have been migrated, /dev/sdb1 no longer holds any allocated data, allowing vgreduce to remove it and pvremove to release the label. This is the documented first step before detaching a PV from an active VG.
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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
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