RAID capacity calculator
Work out usable capacity, how many drives can fail, and storage efficiency for any RAID level - instantly.
Result
- Usable capacity
- 24 TB
- Raw total
- 32 TB
- Lost to redundancy
- 8 TB
- Drives that can fail
- 1
- Storage efficiency
- 75%
How the RAID levels compare
- RAID 0 - stripes data across all drives. Fastest and full capacity, but zero redundancy - one failure loses everything.
- RAID 1 - mirrors drives. Survives all-but-one failing; usable capacity is just one drive.
- RAID 5 - single parity (min 3 drives). Loses one drive of capacity, survives one failure.
- RAID 6 - double parity (min 4). Loses two drives of capacity, survives two failures - the safer choice for large arrays.
- RAID 10 - striped mirrors (even count, min 4). Fast and resilient, but you lose half the capacity.
- JBOD - independent drives, no redundancy.
Bigger drives mean longer rebuilds, which is why double parity (RAID 6) is recommended once arrays get large. For how many drives to buy, see RAID and how many drives you need. And remember: RAID is not a backup.