Deploying QLC at Scale: Balancing Density, Power, Performance, And Reliability

Author: Ben Dequal, Product Management, Pure Storage Collection: 2025 OCP Global Summit - Expo Hall Sessions

Summary

Pure Storage makes the case that QLC flash is the optimal balanced storage technology for emerging AI workloads, offering 150 TB drives today with 600 TB expected within 12-18 months, compared to ~50 TB for HAMR HDDs and 30 TB for TLC. Normalized per TB against HDD, QLC delivers 60x read throughput, 7x write throughput, 2,000x IOPS, at 0.5x the power and 3x the cost. The presentation acknowledges four adoption challenges and presents Pure's solutions for each.

The E2 form factor -- jointly developed by Pure Storage, Meta, Microsoft, Micron, and others -- is a new high-density OCP-compliant drive standard specifying 25W per drive (current spec) with potential for 80W with water cooling, designed for PCIe Gen 7 and beyond, with a roadmap to over 1 PB per single drive. Pure's DirectFlash architecture runs flash memory management in host software rather than on-drive controllers, enabling: data packing by temporal correlation to reduce write amplification (solving QLC endurance at <0.3 DWPD); system-level parity protecting against whole drive failures without extra capacity (solving error correction at extreme densities); and 512KB indirection units (IU) with delayed write coalescing reducing mapping memory from ~1 TB per PB to just 8 GB per PB (solving resource efficiency). Pure has achieved extremely low annual failure rates despite 600 TB drive densities and has been running their U2L flash management approach for 9 years.