APAC 4x 20TB RAID 10 NAS Calculator

Estimate usable TB, parity, and fault tolerance for APAC homelab buyers using 4x 20TB in RAID 10.

Capacity Snapshot

Raw Capacity

80.00 TB

Usable Capacity

36.00 TB

Fault Tolerance

1 drive per mirror pair*

Efficiency

50.0%

Excellent random I/O and rebuild behavior; capacity is typically 50% of raw. 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 10 NAS Calculator Next: Synology 4x 20TB RAID-Z1 NAS Calculator →

FAQ

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.

How much real-world usable storage does 4x 20TB RAID 10 provide?

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

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.

Should I optimize this 4-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.