As data volumes continue to grow, space efficiency becomes a key concern for modern IT infrastructures. With the release of VMware Cloud Foundation 9.0, organizations can take advantage of new capabilities in vSAN to significantly optimize storage consumption without compromising performance.
In this article, we explore the opportunistic and deterministic space efficiency features built into vSAN, comparing the capabilities of the Original Storage Architecture (OSA) and the newer Express Storage Architecture (ESA).
Opportunistic features deliver savings based on data compressibility and structure, but results may vary. Key capabilities include:
Compression (ESA): In ESA, compression happens immediately at the top of the vSAN stack, before data is written to disk or transmitted across the network. This drastically reduces CPU and network utilization while improving performance—especially in stretched clusters.
Global Deduplication (ESA): Unlike OSA, where deduplication is disk group-bound, ESA enables cluster-wide deduplication with adaptive throttling. Deduplication is performed post-write and prioritizes cold data, minimizing performance impact.
Deduplication & Compression (OSA): In OSA, deduplication and compression are performed during destaging, which may degrade performance depending on the capacity tier. It’s a viable option for legacy environments but introduces latency in high-throughput workloads.
Compression-Only Mode (OSA): Introduced in vSAN 7 U1, this mode offers a middle ground—providing space savings without the overhead of deduplication. It’s particularly beneficial for performance-sensitive environments using modern flash storage.
These features guarantee capacity savings by using RAID-level redundancy instead of simple mirroring.
RAID-5/6 (ESA): With ESA, RAID-5 and RAID-6 deliver deterministic space efficiency without performance penalties. For instance, RAID-5 (4+1) consumes just 1.25x the data footprint, making it ideal for clusters with 6+ nodes.
RAID-5/6 (OSA): OSA uses a 3+1 or 4+2 data placement strategy. While this offers a significant reduction in capacity consumption compared to RAID-1, it comes at the cost of higher CPU, network, and I/O overhead—especially under high write loads.
Additional vSAN Space Saving Tools:
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Thin Provisioning: Efficient allocation of disk capacity on demand.
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TRIM/UNMAP: Reclaims unused space after guest OS deletions.
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Storage Policies: Fine-tuned controls for per-object resiliency and efficiency.
Recommendations:
Choose ESA whenever possible – It delivers superior space savings with no performance trade-offs.
Use Compression-only (OSA) for performance-sensitive workloads on legacy hardware.
Apply RAID-5/6 erasure coding in ESA to reduce capacity usage while maintaining high resilience.
Monitor space savings via vCenter Capacity View, and stay current with the latest vSAN releases to benefit from performance and efficiency enhancements.
With vSAN in VMware Cloud Foundation 9, organizations can confidently strike a balance between performance, resilience, and capacity optimization. Whether you’re modernizing with ESA or managing legacy OSA clusters, understanding and applying the right space efficiency techniques is key to maximizing your investment.
For hands-on workshops or custom vSAN training sessions, feel free to get in touch.
