Practical guide
Compare NAS capacity with a retention workload
Capacity is only useful when it is compared with the workload it must retain. ArrayKeep keeps full data, daily change volume, retention days, copies, and overhead as separate inputs.
Build the retention estimate
The default workload starts with 4 TB, adds 50 GB per day for 30 days, uses one copy, and adds 10% backup overhead. The engine reports an estimated requirement of 6.05 TB.
requirement = (full TB + daily GB x retention days / 1000) x copies x (1 + overhead / 100)
Compare space after the estimate
The default 21.6 TB usable result leaves 15.55 TB after the estimated backup requirement. Change copies or retention before treating the comparison as a purchase input.
4 TB plus 50 GB x 30 days is 5.5 TB before the default copy and overhead inputs.
Keep RAID separate from backup
RAID layout and backup retention answer different questions. Keep an independent copy and test restoration through the process appropriate to the data, rather than treating array capacity as the backup itself.
Check your own scenario
Replace the illustrative inputs with measured values and dated specifications.
Open ArrayKeep Storage PlannerMethod and references
Read the full calculation method and its limits
Method and examples reviewed 2026-09-30. Examples are illustrative; input values and specifications are not independently verified.