LPIC-2 Practice Question: Block Devices, Filesystems and Advanced Storage
A system administrator needs to create a RAID 10 array using four disks: /dev/sdb, /dev/sdc, /dev/sdd, /dev/sde. Which TWO commands correctly achieve this?
⚠ Common exam trap
Test-takers frequently think only `--level=10` is valid, but mdadm also accepts `--level=raid10` as a synonym, and they may confuse RAID 10 with RAID 1 or RAID 0 syntax, leading them to select options that create the wrong RAID level or use incorrect device counts.
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
✓
mdadm --create /dev/md0 --level=10 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde
`--level=10` is the accepted syntax for RAID 10 in mdadm, and specifying `--raid-devices=4` with all four disks creates a RAID 10 array (a stripe of mirrors) directly. Option C is also correct because `--level=raid10` is an alternative valid syntax that mdadm accepts for the same RAID level.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
mdadm --create /dev/md0 --level=10 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde
Why this is correct
Correct: Numeric level 10 with 4 devices creates RAID 10.
- ✗
mdadm --create /dev/md0 --level=1 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde
Why it's wrong here
Incorrect: This creates RAID 1 (mirroring), not RAID 10.
- ✓
mdadm --create /dev/md0 --level=raid10 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde
Why this is correct
Correct: Using the word 'raid10' is equivalent to level 10.
- ✗
mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sdb /dev/sdc --add /dev/md1
Why it's wrong here
Incorrect: Invalid syntax; --add is not used in --create and the device count is wrong.
- ✗
mdadm --create /dev/md0 --level=10 --raid-devices=2 /dev/sdb /dev/sdc
Why it's wrong here
Incorrect: Only two devices are specified, but RAID 10 requires at least 4.
Quick reference
RAID Level Comparison
| RAID Level | Min Disks | Fault Tolerance | Read | Write | Usable Capacity |
|---|---|---|---|---|---|
| RAID 0 | 2 | None | Excellent | Excellent | 100% |
| RAID 1 | 2 | 1 disk | Good | Moderate | 50% |
| RAID 5 | 3 | 1 disk | Good | Moderate | 67–94% |
| RAID 6 | 4 | 2 disks | Good | Lower | 50–88% |
| RAID 10 | 4 | 1 disk per mirror | Excellent | Good | 50% |
RAID is not a backup strategy — it protects against disk failure but not against accidental deletion, ransomware, or site-level events.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-2 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-2 exam.