APAC 4x 20TB RAID 6 NAS Calculator

Estimate usable TB, parity, and fault tolerance for APAC homelab buyers using 4x 20TB in RAID 6.

Capacity Snapshot

Raw Capacity

80.00 TB

Usable Capacity

36.00 TB

Fault Tolerance

2 drives

Efficiency

50.0%

Safer for larger arrays with dual parity, at the cost of one extra parity disk. This scenario applies a 10% filesystem reserve.

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Alternative Mode Comparison

Mode	Usable	Tolerance	Efficiency
RAID 5	54.00 TB	1 drive	75.0%
RAID 6	36.00 TB	2 drives	50.0%
RAID 10	36.00 TB	1 drive per mirror pair*	50.0%
RAID-Z1	54.00 TB	1 drive	75.0%
RAID-Z2	36.00 TB	2 drives	50.0%

APAC Buyer Context

APAC builders frequently compare availability windows and procurement variance, which makes robust fallback capacity and staged scaling useful in practice.

• Plan a spare strategy alongside RAID level selection.
• Validate that chosen parity can tolerate delayed disk replacement windows.

Brand / Region Glossary

Procurement Variance

Regional differences in disk availability and replacement lead times.

Spare Strategy

Policy of keeping spare disks available to reduce recovery delay risk.

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: EU 4x 20TB RAID 6 NAS Calculator Next: Synology 4x 20TB RAID 10 NAS Calculator →

FAQ

Should I optimize this 4-drive plan for capacity 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.

How much usable storage does 4x 20TB RAID 6 provide?

For APAC homelab buyers, this NAS planning scenario estimates 36.00 TB usable after a 10% reserve from 80.00 TB raw.

Is RAID 6 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.

Why include a 10% reserve when planning NAS capacity?

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