The correct first step is to add a new disk, create a physical volume (PV) on it, and extend the volume group vg_root using vgextend. This is necessary because the volume group currently has no free extents, meaning there is no available space to allocate for a new logical volume. The core concept here is that logical volumes are carved from free extents within a volume group; if the volume group is full, you must first expand its capacity by adding a new PV. On the LFCS exam, this scenario tests your understanding of the LVM storage workflow: PV → VG → LV, and the trap is that many candidates try to run lvcreate immediately without checking available space. A common memory tip is “No free extents? Add a disk first—PV, then vgextend, then lvcreate.” This ensures you always follow the correct sequence when expanding storage in a constrained volume group.
LFCS Storage Management Practice Question
This LFCS practice question tests your understanding of storage management. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Network Topology
The administrator wants to create a new logical volume of 5GB for /var/log. Which of the following is the most appropriate first step?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a new disk (e.g., /dev/sdc) to the system, create a PV, and extend vg_root.
Option B is correct because the volume group vg_root currently has no free space to create a new logical volume. Adding a new disk, creating a physical volume (PV) on it, and extending vg_root with vgextend provides the necessary free extents. Only then can lvcreate be used to create the 5GB lv_var_log logical volume for /var/log.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use lvresize to shrink lv_root by 5G and then create lv_var_log
Why it's wrong here
Shrinking root LV is risky and not straightforward.
✓
Add a new disk (e.g., /dev/sdc) to the system, create a PV, and extend vg_root.
Why this is correct
This provides free space to create the new LV.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Mount a new filesystem directly on a new partition /dev/sdc1
Why it's wrong here
No new disk is mentioned; also not using LVM.
✗
Use lvcreate -L 5G vg_root -n lv_var_log
Why it's wrong here
vg_root has no free space.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume lvcreate can always create a new logical volume in an existing volume group, forgetting that the VG must have sufficient free space; they overlook the prerequisite of adding a new PV when the VG is full.
Detailed technical explanation
How to think about this question
LVM uses physical volumes (PVs) as the underlying storage, grouped into volume groups (VGs). The vgdisplay command shows free PE (Physical Extents) in the VG; if none exist, you must add a new PV (e.g., /dev/sdc) and extend the VG with vgextend vg_root /dev/sdc. Only then can lvcreate allocate the required extents. In real-world scenarios, administrators often use pvcreate, vgextend, then lvcreate to add storage without downtime.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Storage Management — This question tests Storage Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a new disk (e.g., /dev/sdc) to the system, create a PV, and extend vg_root. — Option B is correct because the volume group vg_root currently has no free space to create a new logical volume. Adding a new disk, creating a physical volume (PV) on it, and extending vg_root with vgextend provides the necessary free extents. Only then can lvcreate be used to create the 5GB lv_var_log logical volume for /var/log.
What should I do if I get this LFCS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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