Methodology
Make the storage plan inspectable.
The planner exposes data growth, headroom, simple parity capacity, and backup-target assumptions so the result can become a specification brief you verify.
Core equations
Forecast data: current protected data + monthly growth × planning months.
Capacity target: forecast data × visible planning headroom.
Simple protected layout: target capacity ÷ data-drive equivalents after selected parity.
Backup target: protected capacity target plus room for the chosen recovery retention and future growth.
Evidence sources
Synology drive replacement and expansion guidance
Platform-specific conditions for capacity changes after drive replacement.
Open source ↗Synology RAID Calculator
Capacity estimation for supported Synology drive combinations.
Open source ↗TrueNAS ZFS Capacity Calculator
ZFS capacity, redundancy, and configuration-planning reference.
Open source ↗TrueNAS replication tasks
Platform documentation for snapshot replication and backup workflows.
Open source ↗CISA ransomware guide
Independent backups and recovery-testing guidance.
Open source ↗Seagate CMR and SMR model list
Model-level recording-technology reference.
Open source ↗Backblaze Drive Stats dataset
Data-center drive observations for context, not home-NAS failure prediction.
Open source ↗Scope
The tool supports early planning. Exact usable capacity, mixed-drive behavior, compatibility, firmware, drive health, encryption, backup software, retention, and recovery performance must be verified for the actual platform and hardware.