350-601 RAID-10 Practice Question
An organization's storage network uses RAID-10 for critical databases. The storage array has 12 disks. How many disks can fail simultaneously without data loss, assuming the worst-case scenario?
⚠ Common exam trap
RAID-10 can tolerate up to one disk failure per mirrored pair. With 6 pairs, up to 6 disks can fail simultaneously as long as no two failures occur in the same pair. The 'worst-case scenario' often misleads candidates into thinking only one disk can fail, but the intended interpretation is that failures are spread across different mirrors.
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
✓
6
RAID-10 combines mirroring and striping. With 12 disks, there are 6 mirrored pairs. Data is lost only if both disks in the same mirror fail. Therefore, as long as no more than one disk per mirror fails, up to 6 disks can fail simultaneously without data loss. The phrase 'worst-case scenario' often confuses candidates into thinking only 1 failure is tolerable, but the question asks for the maximum number that can fail without data loss, which is 6.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
6
Why this is correct
RAID-10 can tolerate up to 6 disk failures as long as no mirror loses both disks.
- ✗
11
Why it's wrong here
That would be all but one, not possible in RAID-10.
- ✗
2
Why it's wrong here
Only 2 if they are in different mirrors, but up to 6 is the maximum.
- ✗
1
Why it's wrong here
In the worst case, if two disks in the same mirror fail, data is lost. But overall, up to 6 can fail if they are in different mirrors.
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
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