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3x 8TB RAID-Z1 NAS Calculator | Usable TB

Estimate usable TB, parity overhead, and fault tolerance for 3x 8TB in RAID-Z1. Includes reserve planning for NAS and homelab arrays.

Capacity Snapshot

Raw Capacity

24.00 TB

Usable Capacity

14.40 TB

Fault Tolerance

1 drive

Efficiency

66.7%

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	14.40 TB	1 drive	66.7%
RAID 6	N/A	N/A	N/A
RAID 10	N/A	N/A	N/A
RAID-Z1	14.40 TB	1 drive	66.7%
RAID-Z2	N/A	N/A	N/A

NAS Cluster Guides

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

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Sequential Long-Tail Navigation

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FAQ

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.

Is RAID-Z1 still viable with 8TB drives?

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

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.

How much effective storage does 3x 8TB RAID-Z1 provide?

This NAS planning scenario estimates 14.40 TB usable after a 10% reserve from 24.00 TB raw.