Trend in HW costs and their effect on windowPoSt security margin

@ June 2023

🌐 Context:

• assuming the current analysis for SDR;
• assuming same or similar HW configuration for PC1 as today (ie, mainly CPU)
• assuming no software improvements for PC1 (after the one shipped by the Supranational team in June 2023)
• ie, Supranational team optimized it about as far as they could take it on the current HW and there is no a plan to continue this work in the short/middle term.
• considering HW (CPU and NVMe) cost trend over time (ie, cheaper CPU cost in 6 months, 1 year, 2 years respect today);
• considerinf HDD cost trend over time

🎯 Goal:

• estimate the windowPoSt security margin in 6 months, 1 year, 2 years (see for the definition of security margin)

📐 Analisys:

Current value [from now to 6 months]

• CS = $0.000896 per 32GiB ($37.6 per TB, 1.25 redundancy)
• RC = $0.00185 (SN Expectation 2023)
• Security Margin = 2.06

See for details

Trend data:

💾 HDD cost trend: given data form the past (see the graph below), we do not expect the cost of HDD to diminish significantly in the next 2 years. We consider a 5% decrease every year.

💻 CPU and NVMe cost trend:

• for CPU, given data form the past (see the graph below), we consider a 40% decrease every year.
• for NVMe (solid state), the decrease seems to be smaller (around ~20% every year), but to be on the safe side, we overall consider a 40% decrease in the HW cost for PC1

Projected values:

• 6 months - 1 year
• CS = 5% less than current = $0.000851
• RC = 40% less than current = $0.00111
• Security Margin = 1.3
• 1 year - 2 years
• CS = 5% less than $0.000851 = $0.00080845
• RC = 40% less than $0.00111= $0.000666
• Security Margin = 0.82 (<1)