Synology 10x 12TB RAID-Z1 NAS Calculator

Estimate usable TB, parity, and fault tolerance for Synology NAS users using 10x 12TB in RAID-Z1.

Capacity Snapshot

Raw Capacity

120.00 TB

Usable Capacity

97.20 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	97.20 TB	1 drive	90.0%
RAID 6	86.40 TB	2 drives	80.0%
RAID 10	54.00 TB	1 drive per mirror pair*	50.0%
RAID-Z1	97.20 TB	1 drive	90.0%
RAID-Z2	86.40 TB	2 drives	80.0%

Synology Planning Notes

Synology users usually optimize for predictable rebuild behavior and conservative free-space policies, especially when using large-capacity SHR/RAID pools for media and backup workloads.

• Keep spare bays in your growth plan so expansions do not force emergency migrations.
• Budget extra free space for snapshot retention and background indexing tasks.
• Prefer dual-parity style layouts for larger pools with long rebuild windows.

Brand / Region Glossary

SHR

Synology Hybrid RAID that improves flexibility when mixing drive sizes.

Btrfs Snapshots

Point-in-time snapshots used for rollback and data protection policies.

Storage Pool

Logical disk group where RAID layout is created before volumes are provisioned.

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

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FAQ

Should I optimize this 10-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.

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.

Is RAID-Z1 still practical with 12TB drives?

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

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.