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10x 20TB RAID-Z1 NAS Calculator | Usable TB

Estimate usable TB, parity overhead, and fault tolerance for 10x 20TB in RAID-Z1. Includes reserve planning for NAS and homelab arrays.

Capacity Snapshot

Raw Capacity

200.00 TB

Usable Capacity

162.00 TB

Fault Tolerance

1 drive

Efficiency

90.0%

ZFS single-parity equivalent of RAID 5; common for smaller homelab pools. This scenario applies a 10% filesystem reserve.

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Alternative Mode Comparison

Mode Usable Tolerance Efficiency
RAID 5 162.00 TB 1 drive 90.0%
RAID 6 144.00 TB 2 drives 80.0%
RAID 10 90.00 TB 1 drive per mirror pair* 50.0%
RAID-Z1 162.00 TB 1 drive 90.0%
RAID-Z2 144.00 TB 2 drives 80.0%

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: 10x 20TB RAID 10 NAS Calculator | Usable TB Next: 10x 20TB RAID-Z2 NAS Calculator | Usable TB →

FAQ

Is RAID-Z1 still practical with 20TB drives?

It can be practical, but larger drives increase rebuild windows. Validate parity choice and backup policy before committing to the final layout.

How many disk failures can RAID-Z1 tolerate in this setup?

This setup can tolerate 1 drive. Real-world survivability depends on mirror placement, rebuild stress, and drive health.

Should I optimize this 10-drive plan for storage headroom or resiliency first?

For long-lived NAS pools, resiliency first is usually safer. Capacity can be expanded later, while a risky parity choice can force migration sooner.

Why include a 10% reserve when planning NAS available space?

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