← NAS & RAID Calculator

NAS pSEO Landing

5x 18TB RAID 1 NAS Calculator | Usable TB

Estimate usable TB, parity overhead, and fault tolerance for 5x 18TB in RAID 1. Includes reserve planning for NAS and homelab arrays.

Capacity Snapshot

Raw Capacity

90.00 TB

Usable Capacity

16.20 TB

Fault Tolerance

4 drives*

Efficiency

20.0%

Strong redundancy but low capacity efficiency. Great for small, critical datasets. This scenario applies a 10% filesystem reserve.

Run Interactive Calculator →

Alternative Mode Comparison

Mode Usable Tolerance Efficiency
RAID 5 64.80 TB 1 drive 80.0%
RAID 6 48.60 TB 2 drives 60.0%
RAID 10 N/A N/A N/A
RAID-Z1 64.80 TB 1 drive 80.0%
RAID-Z2 48.60 TB 2 drives 60.0%

NAS Cluster Guides

NAS Hub RAID Level Compare RAID Capacity Matrix Planning Quick Sheet RAID Selector NAS FAQ

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

Sequential Long-Tail Navigation

← Previous: 5x 16TB RAID-Z2 NAS Calculator | Usable TB Next: 5x 18TB RAID 5 NAS Calculator | Usable TB →

FAQ

How much real-world usable storage does 5x 18TB RAID 1 provide?

This NAS planning scenario estimates 16.20 TB usable after a 10% reserve from 90.00 TB raw.

How many disk failures can RAID 1 tolerate in this setup?

This setup can tolerate 4 drives*. Real-world survivability depends on mirror placement, rebuild stress, and drive health.

Why include a 10% reserve when planning NAS storage headroom?

Keeping free space improves filesystem behavior for snapshots, metadata, and write performance. Full arrays often perform worse and rebuild more slowly.

Can this calculator replace real-world benchmark and rebuild testing?

No. Use this page for pre-purchase sizing, then validate with workload benchmarks, SMART health policy, and a tested restore plan.