vSAN 9.0 has received two transformative upgrades that fundamentally change how we think about data efficiency and cyber-resilience: Global Deduplication and vSAN-to-vSAN Replication with Deep Snapshots.
- vSAN ESA Global Deduplication:
In previous versions (vSAN OSA), deduplication was limited to the “Disk Group” level. This meant if you had identical data on two different disk groups within the same host, the system couldn’t “see” the duplication.
With vSAN 9.0 Express Storage Architecture (ESA), deduplication has gone Global. It now operates across the entire cluster, creating a single, massive deduplication domain.
Why it is important: - By moving to a cluster-wide domain and utilizing a fine-grained 4KB block size, vSAN 9.0 can achieve up to an 8x reduction in storage footprint, a massive jump from the 2x typical in older architectures.
- Unlike legacy systems where dedupe can “choke” the write path, vSAN 9.0 uses an asynchronous post-process approach. Data is written at full speed to the NVMe tier first, and then deduplicated in the background when resources are available.
- Because VCF 9.0 licensing includes 1TiB of vSAN capacity per core, every byte you save through global dedupe is essentially “bonus” capacity you don’t have to pay extra for.
- vSAN-to-vSAN Replication & Deep Snapshots:
Ransomware is no longer a “maybe”; it’s a “when.” VCF 9.0 addresses this head-on by integrating vSAN-to-vSAN Replication directly into the storage stack. This isn’t just basic copying; it’s a specialized data protection engine.
What is different with Deep Snapshots: - Built on the vSAN ESA log-structured file system, these snapshots can be kept for days or weeks without the “snapshot stun” or latency issues associated with traditional chains.
- These snapshots can be locked, preventing ransomware from deleting your recovery points even if it gains administrative access.
- You can replicate these snapshots to a remote vSAN site as frequently as every 1 minute. If a primary site is hit, you have a “deep” history of clean points to roll back to.
| Feature | Legacy vSAN | vSAN 9.0 (ESA) |
| Deduplication Scope | Disk Group | Global (Cluster-Wide) |
| Block Size | 8KB | 4KB (More efficient) |
| Snapshot Impact | High (over time) | Near-Zero (Deep Snapshots) |
| Replication | External/Appliance | Native vSAN-to-vSAN |
Reference Links:
https://blogs.vmware.com/cloud-foundation/2025/06/19/global-deduplication-in-vsan-esa-for-vmware-cloud-foundation-9-0/
https://www.vmware.com/docs/vsan-solution-overview