Size your SAN storage array with capacity projections for data growth, snapshots, and replication. Plan procurement years ahead.
Sizing a Storage Area Network (SAN) requires accounting for far more than just current data volumes. Snapshots, replication, data growth, thin provisioning overhead, and spare capacity all consume space that must be planned for. Under-sizing leads to emergency expansions at premium prices, while over-sizing wastes capital on shelf-ware.
This calculator models SAN capacity over time by combining your usable storage requirements with growth projections, snapshot retention, and replication overhead. Enter your current usable capacity, annual growth rate, snapshot policy, and replication needs, and get a multi-year capacity forecast. Use the results to time your hardware refresh cycles and negotiate volume pricing with storage vendors.
Quantifying this parameter enables systematic comparison across environments, deployments, and time periods, revealing optimization opportunities that improve both performance and cost-effectiveness. This analytical approach supports proactive infrastructure management, helping teams avoid costly outages and maintain the service levels that users and business stakeholders depend on.
Quantifying this parameter enables systematic comparison across environments, deployments, and time periods, revealing optimization opportunities that improve both performance and cost-effectiveness.
SAN hardware has long lead times and significant procurement cycles. This calculator gives you the data to justify purchases, time expansions, and avoid costly emergency orders by projecting capacity needs years into the future. Data-driven tracking enables evidence-based infrastructure decisions, reducing the risk of over-provisioning costs or under-provisioning that leads to performance bottlenecks.
projected_usable = current_TB × (1 + annual_growth / 100) ^ years; snapshot_overhead = projected_usable × (snapshot_pct / 100); total = (projected_usable + snapshot_overhead) × replication_multiplier
Result: 195.3 TB total
50 TB growing at 25% for 3 years = 50 × 1.25³ = 97.66 TB usable. Snapshot overhead adds 20% = 19.53 TB, giving 117.19 TB. With replication (2×), total needed is 234.38 TB raw. This demonstrates how 50 TB of current data requires nearly 5× the raw capacity in 3 years.
SAN hardware typically has a 3–5 year lifecycle. Plan your initial purchase to cover at least 3 years of projected growth, with expansion shelves available for years 4–5. This approach balances capital efficiency with operational flexibility.
Modern SANs with inline deduplication and compression can reduce physical capacity needs by 2–5× for general workloads and up to 10× for VDI environments. However, already-compressed data (images, video, encrypted data) sees minimal reduction. Size for the worst case and enjoy the savings.
Hybrid SAN solutions tier cold data to the cloud while keeping hot data on local flash. This can reduce on-premises capacity needs by 30–60% for workloads with significant cold data. Factor in cloud storage costs and retrieval latency when evaluating this option.
Industry averages are 20–40% annually, but this varies widely. Measure your actual growth over the past 12 months for the best estimate. Data-intensive workloads (analytics, media) can grow 50%+ per year.
Snapshot space depends on data change rate and retention. A snapshot of a 10 TB volume with 5% daily change retained for 7 days uses roughly 3.5 TB (5% × 10 × 7). Frequently changing databases consume more snapshot space.
The multiplier accounts for copies of data for disaster recovery. A multiplier of 2 means one additional copy (source + replica). Synchronous replication to a DR site doubles your raw storage requirement.
RAID 5 loses one disk per group to parity (~20–25% overhead). RAID 6 loses two disks (~30–35%). RAID 10 uses half the raw capacity. Divide usable capacity by the RAID efficiency to get raw disk requirements.
Thin provisioning delays physical allocation, but the data will eventually be written. Plan for the full projected usage, not the thin-provisioned amount. Over-committing thin provisioning is a leading cause of SAN outages.
Start the procurement process when utilization hits 70%. Most SAN expansions take 4–12 weeks from order to installation. By 80% utilization, performance may degrade. Never let a SAN exceed 85–90% utilization.