This LPIC-1 practice question tests your understanding of devices, filesystems and fhs. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 ext4 filesystem is experiencing performance degradation due to very frequent small writes. Which tune2fs option can help by reserving a percentage of blocks for the root user to prevent fragmentation?
-i 0
Why wrong: -i sets check interval in days.
-g root
Why wrong: -g sets the group that can use reserved blocks, not the percentage.
-c 0
Why wrong: -c sets max mount count before forced fsck, not reserved blocks.
-m 0
-m sets reserved block percentage; setting to 0 frees space for all users but may increase fragmentation.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
-m 0
Option D is correct because the `-m 0` option in tune2fs sets the reserved blocks percentage to 0, which prevents the filesystem from reserving a percentage of blocks exclusively for the root user. This reduces fragmentation from frequent small writes by allowing all blocks to be used for data, avoiding the scenario where small files are scattered across reserved and unreserved areas. The reserved blocks are typically 5% by default, and setting it to 0 can improve performance for high-write workloads.
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.
-i 0
Why it's wrong here
-i sets check interval in days.
-g root
Why it's wrong here
-g sets the group that can use reserved blocks, not the percentage.
-c 0
Why it's wrong here
-c sets max mount count before forced fsck, not reserved blocks.
-m 0
Why this is correct
-m sets reserved block percentage; setting to 0 frees space for all users but may increase fragmentation.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse `-m 0` with disabling filesystem checks (options A or C) or think `-g root` is a valid way to reserve blocks for root, when in fact `-m` directly controls the reserved block percentage and is the correct tool for this purpose.
Detailed technical explanation
The reserved blocks percentage (set with `-m`) is designed to prevent filesystem fragmentation by ensuring that the root user always has contiguous space for critical system operations, but for workloads with very frequent small writes, this reservation can actually increase fragmentation as files are forced into non-reserved areas. Under the hood, ext4 uses block groups and the reserved blocks are allocated from each block group, so setting `-m 0` allows all block groups to be fully utilized, reducing the need for the allocator to search across groups. In real-world scenarios like database logs or container workloads, this tuning can significantly improve write performance and reduce wear on SSDs.
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 LPIC-1 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
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FAQ
Devices, Filesystems and FHS — This question tests Devices, Filesystems and FHS — Read the scenario before looking for a memorised answer..
The correct answer is: -m 0 — Option D is correct because the `-m 0` option in tune2fs sets the reserved blocks percentage to 0, which prevents the filesystem from reserving a percentage of blocks exclusively for the root user. This reduces fragmentation from frequent small writes by allowing all blocks to be used for data, avoiding the scenario where small files are scattered across reserved and unreserved areas. The reserved blocks are typically 5% by default, and setting it to 0 can improve performance for high-write workloads.
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 LPIC-1 practice question is part of Courseiva's free LPI 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 LPIC-1 exam.
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