Backup Storage Sizing Tool (BSZT)

1 Project details

Project name Customer / organisation Site / location Prepared by Date Notes for the report

2 Backup platform

Platform Backup mode Planning horizon (years) Backup window (hours) Cost of one retained GFS full modelled 35% Share of a stored full that each weekly, monthly or yearly restore point adds. It is modelled from each workload’s change rate and the working set below, the same way for every storage target. Drag the slider only to override it with a figure from a real assessment. Active working set (% of data that changes) Daily change lands mostly on the same active data. About 70% of stored data is typically cold, hence the 30% default.

3 Protected workloads

Name	Type	Size TB	Used %	Growth %/yr	Change %/day	Reduction	Tape

Reduction defaults come from the platform (or the storage target when it deduplicates) and the workload type; override any cell to match a real assessment.

4 Retention policy (GFS)

Daily Weekly Monthly Yearly

Daily points are incrementals in the active chain. Weekly, monthly and yearly points are full restore points (GFS).

5 Backup storage target

Storage OEM Model

Protection scheme Disks per parity group Drive size (TB) Hot spares

6 Overheads & headroom

Reserve capacity for immutability / WORM Index & metadata % Working / merge space % Immutability reserve % File-system overhead % Free-space reserve %

7 Secondary copy & archive

Include a secondary / offsite copy Copy target Replication window (hours) Copy daily points Copy weekly points Copy monthly points Copy yearly points

Include a long-term archive tier Archive retention (years) Archive points per year Archive point size, % of a full 100%

8 Tape library

Size a tape library Media generation Tape copy is taken from Compression achieved on tape Copy sets (onsite + offsite) Weekly fulls retained Monthly fulls retained Yearly fulls retained Vaulted offsite % Scratch / spare media % Tape window (hours) Drive efficiency % Cleaning cartridges

BSZT produces planning estimates. Data reduction ratios dominate the result — validate them with a real assessment of the customer environment before issuing a bill of materials.

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