Synology RAID-Z2 vs RAID-Z1 Calculator

Compare usable TB, parity, and failure tolerance between RAID-Z2 and RAID-Z1 for Synology NAS users.

Comparison Notes

This page compares RAID-Z2 and RAID-Z1 on identical hardware assumptions to help homelab builders choose between capacity efficiency and fault tolerance.

Disk size baseline: 8TB drives
Reserve policy: 10% filesystem headroom
Use the interactive tool for exact real-world constraints

Open Interactive Planner →

Storage Capacity Table

Drives	RAID-Z2	RAID-Z1	Delta
4x 8TB	14.40 TB	21.60 TB	-7.20 TB
6x 8TB	28.80 TB	36.00 TB	-7.20 TB
8x 8TB	43.20 TB	50.40 TB	-7.20 TB
10x 8TB	57.60 TB	64.80 TB	-7.20 TB
12x 8TB	72.00 TB	79.20 TB	-7.20 TB

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

← Previous: APAC RAID 6 vs RAID 5 Calculator Next: QNAP RAID-Z2 vs RAID-Z1 Calculator →

FAQ

Can two layouts with similar storage headroom still have very different failure exposure?

Yes. Similar usable TB does not imply similar failure tolerance or rebuild exposure. Capacity and resiliency should be evaluated together.

Does this comparison include filesystem reserve?

Yes. The comparison table applies a 10% reserve baseline to reflect realistic operating headroom in NAS and homelab environments.

Does RAID-Z2 rebuild faster than RAID-Z1?

Rebuild behavior depends on array width, disk size, and workload pressure. This page focuses on capacity and tolerance; benchmark your actual platform before final choice.

How should I choose between RAID-Z2 and RAID-Z1?

Choose based on your risk tolerance, rebuild window, and performance profile. Higher parity usually lowers capacity but improves resilience.