EX200 Configure local storage Practice Question
A system administrator needs to add a new 10GB disk to an existing volume group 'vgdata' to extend logical volumes. Which of the following is the correct sequence of commands?
⚠ Common exam trap
Many exam-takers think `vgextend` can automatically initialize the disk, or that the order of commands does not matter, but LVM strictly requires `pvcreate` before `vgextend` and `vgextend` before `lvextend`.
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
✓
pvcreate /dev/sdb, vgextend vgdata /dev/sdb, lvextend
The proper sequence to add a new disk to an existing volume group is: first create a physical volume with `pvcreate /dev/sdb`, then extend the volume group with `vgextend vgdata /dev/sdb`, and finally extend the logical volume with `lvextend`. This order ensures the disk is initialized as a PV before it can be added to the VG, and the VG must have the new PV before the LV can be extended.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
pvcreate /dev/sdb, vgextend vgdata /dev/sdb, lvextend
Why this is correct
pvcreate initializes /dev/sdb with LVM metadata, making it a physical volume that LVM can recognize. vgextend then adds that PV to the existing volume group vgdata, increasing its total allocatable space. Only after the VG has free physical extents can lvextend allocate from them to grow a logical volume, followed by a filesystem resize if needed. This dependency chain makes the order mandatory.
- ✗
vgextend vgdata /dev/sdb, pvcreate /dev/sdb, lvextend
Why it's wrong here
Running vgextend before pvcreate fails because LVM cannot add a device that lacks a valid physical volume label to a volume group. pvcreate writes the indispensable metadata header that identifies /dev/sdb as an LVM PV; without it, vgextend reports the device as not found or not a physical volume. The correct sequence is to initialize the disk first, then join it to the volume group, and only then extend any LV.
- ✗
pvcreate /dev/sdb, lvextend, vgextend vgdata /dev/sdb
Why it's wrong here
After pvcreate, /dev/sdb is a physical volume but it has not yet been added to vgdata, so the volume group has no new free extents available. An lvextend attempt at this point will fail because the LV's volume group cannot allocate from a PV that is not a member. The vgextend must occur before lvextend to make that free space visible to the logical volume being expanded.
- ✗
lvextend, vgextend vgdata /dev/sdb, pvcreate /dev/sdb
Why it's wrong here
Because lvextend is executed first, it looks for free extents in vgdata before any new disk has been prepared or added, so it cannot find space and aborts. vgextend after that would add /dev/sdb to the VG, but the LV extension already failed, and pvcreate last would merely initialize the disk after the operations that needed it had run. This order violates every dependency in the LVM workflow and cannot succeed.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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