This LFCS practice question tests your understanding of storage management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An administrator is troubleshooting a server that cannot mount an XFS filesystem on /dev/sdb1. The command mount /dev/sdb1 /data fails with 'wrong fs type, bad option, bad superblock'. Which three commands can help diagnose the issue? (Choose three.)
dmesg | tail
Shows recent kernel logs.
xfs_repair -n /dev/sdb1
Checks XFS filesystem in dry-run mode.
fsck /dev/sdb1
Why wrong: fsck may not handle XFS correctly; could cause damage.
xfs_db -c 'sb' -c 'p' /dev/sdb1
Prints superblock information.
blkid /dev/sdb1
Why wrong: Shows UUID and type but not diagnostic.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
dmesg | tail
Option A is correct because `dmesg | tail` displays the kernel ring buffer messages, which often contain detailed error information from the XFS driver when a mount fails. This can reveal specific reasons such as a corrupt superblock, wrong filesystem type detection, or missing kernel support, helping to pinpoint the root cause.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
dmesg | tail
Why this is correct
Shows recent kernel logs.
Related concept
Read the scenario before looking for a memorised answer.
xfs_repair -n /dev/sdb1
Why this is correct
Checks XFS filesystem in dry-run mode.
Related concept
Read the scenario before looking for a memorised answer.
fsck /dev/sdb1
Why it's wrong here
fsck may not handle XFS correctly; could cause damage.
xfs_db -c 'sb' -c 'p' /dev/sdb1
Why this is correct
Prints superblock information.
Related concept
Read the scenario before looking for a memorised answer.
blkid /dev/sdb1
Why it's wrong here
Shows UUID and type but not diagnostic.
Common exam traps
The trap here is that candidates often assume `fsck` is a universal filesystem checker, but it is specific to ext family filesystems and should never be used on XFS, where `xfs_repair` is the correct tool.
Trap categories for this question
Command / output trap
Shows UUID and type but not diagnostic.
Detailed technical explanation
XFS uses a complex on-disk structure with a primary superblock at offset 0 and secondary superblocks for redundancy. The `xfs_db` command (option D) allows direct inspection of the superblock and other metadata, while `xfs_repair -n` performs a read-only check of the filesystem consistency without making changes. In real-world scenarios, a corrupted log or mismatched superblock version can cause mount failures that only these XFS-specific tools can diagnose.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Storage Management — This question tests Storage Management — Read the scenario before looking for a memorised answer..
The correct answer is: dmesg | tail — Option A is correct because `dmesg | tail` displays the kernel ring buffer messages, which often contain detailed error information from the XFS driver when a mount fails. This can reveal specific reasons such as a corrupt superblock, wrong filesystem type detection, or missing kernel support, helping to pinpoint the root cause.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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.
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