LFCS Storage Management Practice Question
A sysadmin is troubleshooting an issue where a software RAID1 array fails to assemble after a reboot. The array was created with mdadm using /dev/sdb1 and /dev/sdc1. The administrator checks /proc/mdstat but the array is not present. They attempt to assemble manually with mdadm --assemble /dev/md0 /dev/sdb1 /dev/sdc1, but it requires a repair. After repair, the array works. To prevent this from happening again, what should the administrator do?
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
✓
Add an entry for the array in /etc/mdadm/mdadm.conf.
Adding an entry for the array in /etc/mdadm/mdadm.conf (or /etc/mdadm.conf) ensures that mdadm reads the configuration at boot and automatically assembles the RAID array. Without this entry, the system does not know which devices belong to the array, causing it to fail to assemble after reboot. Option A (using UUIDs) is a good practice but not mandatory; the array can still be assembled by device names if configured. Option B (setting partition type to 'Linux RAID') is helpful for disk identification but does not directly address the assembly configuration. Option C (rebuilding initramfs) may be required after adding the config, but the primary solution is to add the config entry.
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 UUIDs instead of device names in configuration.
Why it's wrong here
Using UUIDs is good practice, but the core issue is missing mdadm.conf entry.
- ✗
Set the partition type to 'Linux RAID' on both partitions.
Why it's wrong here
While recommended, it is not required for mdadm to assemble at boot.
- ✗
Rebuild the initramfs.
Why it's wrong here
Rebuilding initramfs may help but not as directly as updating mdadm.conf.
- ✓
Add an entry for the array in /etc/mdadm/mdadm.conf.
Why this is correct
Correct: This configuration file ensures automatic assembly at boot.
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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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.