{"slug": "vsan-for-mixed-workloads-policy-design-and-the-osa-to-esa-transition", "title": "vSAN for Mixed Workloads: Policy Design and the OSA-to-ESA Transition", "summary": "VMware vSAN's Express Storage Architecture (ESA) offers significant performance improvements over the legacy Original Storage Architecture (OSA) for mixed workloads, including transactional and AI training. ESA eliminates dedicated cache drives, uses sequential log writes for RAID-5 parity, and supports at-rest encryption with external KMS, enabling sub-millisecond latency for transactional cores and high throughput for AI workloads. Proper Storage Policy-Based Management (SPBM) is critical for balancing these divergent demands on shared infrastructure.", "body_md": "💡\n\nWhat is vSAN OSA & ESA?\n\nVMware vSAN Original Storage Architecture (OSA) is the legacy disk-group-based architecture designed for mixed magnetic/SSD environments. The newer Express Storage Architecture (ESA) is optimized entirely for high-performance NVMe drives, eliminating disk groups in favor of a single Storage Pool.\n\nEnterprise architecture often requires running highly divergent workloads on shared physical infrastructure. Balancing the deterministic latency needed for transactional processing with the massive sequential throughput demanded by AI training profiles represents a classic infrastructure tightrope.\n\nWhen the underlying platform relies on VMware vSAN, achieving this balance comes down to granular Storage Policy-Based Management (SPBM).\n\nDesigning storage policies without analyzing telemetry data under peak load is a recipe for silent performance degradation. Transactional banking cores require minimal write amplification and predictable sub-millisecond read times. Conversely, AI clusters executing large-batch training loops care about raw block delivery and streaming data pipes.\n\nBelow is the operational baseline measured across configurations during peak cluster strain:\n\n| Workload Type | IOPS Range (Peak) | Latency Profile | Focus Metric |\n|---|---|---|---|\nCore Transactional |\n25K - 40K (80K peak) | 0.8ms - 1.2ms | P99 Read Latency |\nAI Workload Training |\n80K - 120K random | 3 - 5 GB/s seq | Throughput Density |\nAI Model Inference |\nSteady demand stream | 0.4ms - 0.7ms | Deterministic P50 |\n\n💡\n\nCalculate vSAN ESA Capacity Instantly:> Storage overhead can quickly break infrastructure budgets if left unmodeled. Instead of wrestling with complex sizing spreadsheets for your new NVMe pools, you can instantly model your RAID-5 overhead and FTT constraints using this live, browser-based[vSAN ESA Capacity Calculator]. It runs completely offline and requires zero signup.\n\nTo survive rigorous third-party infrastructure audits while maintaining high availability, relying on a default \"Cluster-Wide\" policy is insufficient. The architecture must partition workloads logically via explicit SPBM profiles.\n\nData protection requirements in regulated fields often mandate full encryption of sensitive datasets at rest. However, implementation details differ wildly between the two architectures:\n\nYes, provided the hardware stack utilizes certified all-NVMe drives. ESA eliminates the concept of dedicated cache drives, turning every installed drive into a contributing member of both the capacity and performance pools.\n\nLegacy OSA required a multi-step write-modify-write cycle for parity, introducing heavy latency. ESA writes data sequentially into a log append log before structuring it into parity, offering RAID-1 speeds at RAID-5 capacity savings.\n\nYes. Because the encryption occurs before data hits the physical block layer and keys are managed via industry-standard external KMS protocols, it satisfies strict data isolation and segmentation validation criteria.", "url": "https://wpnews.pro/news/vsan-for-mixed-workloads-policy-design-and-the-osa-to-esa-transition", "canonical_source": "https://dev.to/errorbudget/vsan-for-mixed-workloads-policy-design-and-the-osa-to-esa-transition-24jp", "published_at": "2026-06-21 17:13:46+00:00", "updated_at": "2026-06-21 18:04:05.583448+00:00", "lang": "en", "topics": ["ai-infrastructure"], "entities": ["VMware", "vSAN", "Original Storage Architecture (OSA)", "Express Storage Architecture (ESA)", "Storage Policy-Based Management (SPBM)", "NVMe", "RAID-5", "KMS"], "alternates": {"html": "https://wpnews.pro/news/vsan-for-mixed-workloads-policy-design-and-the-osa-to-esa-transition", "markdown": "https://wpnews.pro/news/vsan-for-mixed-workloads-policy-design-and-the-osa-to-esa-transition.md", "text": "https://wpnews.pro/news/vsan-for-mixed-workloads-policy-design-and-the-osa-to-esa-transition.txt", "jsonld": "https://wpnews.pro/news/vsan-for-mixed-workloads-policy-design-and-the-osa-to-esa-transition.jsonld"}}