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Unraid RAID 6 vs RAID 5 Storage Calculator

Compare usable capacity, fault tolerance, and efficiency between RAID 6 and RAID 5 for Unraid NAS users.

Comparison Notes

This page compares RAID 6 and RAID 5 on identical hardware assumptions to help homelab builders choose between capacity efficiency and fault tolerance.

  • Disk size baseline: 8TB drives
  • Reserve policy: 10% filesystem headroom
  • Use the interactive tool for exact real-world constraints
Open Interactive Planner →

Storage Capacity Table

Drives RAID 6 RAID 5 Delta
4x 8TB 14.40 TB 21.60 TB -7.20 TB
6x 8TB 28.80 TB 36.00 TB -7.20 TB
8x 8TB 43.20 TB 50.40 TB -7.20 TB
10x 8TB 57.60 TB 64.80 TB -7.20 TB
12x 8TB 72.00 TB 79.20 TB -7.20 TB

Unraid Planning Notes

Unraid users often optimize for incremental growth and flexible disk replacement, where parity planning and usable capacity targets evolve over time rather than all at once.

Brand / Region Glossary

Parity Disk

Dedicated parity disk(s) protecting data disks in the Unraid array model.

Cache Pool

Fast SSD/NVMe pool used for writes and application workloads.

Mover

Scheduled process that migrates data between cache and array tiers.

Related Long-Tail Calculators

2x 4TB RAID 1 2x 6TB RAID 1 2x 8TB RAID 1 2x 10TB RAID 1 2x 12TB RAID 1 2x 14TB RAID 1 2x 16TB RAID 1 2x 18TB RAID 1 2x 20TB RAID 1 3x 4TB RAID 1 3x 4TB RAID 5 3x 4TB RAID-Z1 3x 6TB RAID 1 3x 6TB RAID 5 3x 6TB RAID-Z1 3x 8TB RAID 1

FAQ

Which option is usually better for long-term homelab growth?

The better option is the one that keeps acceptable usable capacity while preserving safety margins during future disk expansions.

Does RAID 6 rebuild faster than RAID 5?

Rebuild behavior depends on array width, disk size, and workload pressure. This page focuses on capacity and tolerance; benchmark your actual platform before final choice.

Can two layouts with similar available space still have very different rebuild risk?

Yes. Similar usable TB does not imply similar failure tolerance or rebuild exposure. Capacity and resiliency should be evaluated together.

How should I select between RAID 6 and RAID 5?

Choose based on your risk tolerance, rebuild window, and performance profile. Higher parity usually lowers capacity but improves resilience.