Published 11th May 2026
Executive Overview
The massive structural transition from the legacy vSAN Original Storage Architecture (OSA) to the modern, NVMe-optimized Express Storage Architecture (ESA) has traditionally presented an “all-or-nothing” migration challenge. Previously, older OSA clusters could not mount or share storage blocks natively with newer ESA clusters, forcing an operational chasm inside the data center.
With the launch of VMware Cloud Foundation (VCF) 9.1, Broadcom introduces Mixed-Mode Remote Datastore Mounting with Data-in-Transit (DIT) Encryption. This update allows legacy OSA hosts and cutting-edge ESA nodes to share disaggregated storage pools concurrently, while enforcing end-to-end cryptographic isolation. This provides a clear, risk-free pathway for data center modernization during the 2026 hardware supply constraints.
Features
The updated storage routing layer breaks down architecture boundaries by embedding heterogeneous cross-cluster communication mechanics into the hypervisor storage plane.
- Heterogeneous Architecture Cross-Mounting: Enables legacy vSAN OSA clusters, modern ESA clusters, and standard compute-only vSphere clusters to mount remote vSAN datastores simultaneously.
- Decoupled Data-in-Transit (DIT) Encryption: An independent security toggle provided during remote storage mounting. It enforces a unique cryptographic hash for every packet transmitted across the network, completely isolated from the backing storage cluster’s local encryption rules.
- East-West Storage Traffic Throttling: Network scheduling logic within the vSAN cluster that monitors and balances active VM I/O against background cross-cluster migration traffic.
- Transparent Key Management Integration: Leverages standard VCF Key Management Server (KMS) handshakes to automate the distribution and rotation of storage network encryption keys across cluster boundaries.
Benefits
By bridging the gap between legacy and modern software-defined storage formats, VCF 9.1 yields direct financial and operational advantages.
- Life Extension for Legacy Hardware: Rather than abandoning perfectly functional SAS/SATA flash arrays running OSA, organizations can repurpose them to provide extra storage capacity for modern, compute-heavy VCF 9.1 environments.
- Risk-Free OSA-to-ESA Migration: Eliminates the need for disruptive, high-stakes bulk data cold-migrations. Administrators can attach new ESA storage clusters to legacy environments and use non-disruptive Storage vMotion to smoothly transition live workloads.
- Compliance for Disaggregated Storage: Financial and healthcare industries can confidently adopt disaggregated compute/storage topologies (formerly vSAN Max) knowing that back-end storage mirroring networks are fully secured against lateral sniffing attacks.
- Granular Performance and Cost Tuning: The decoupled design lets teams selectively enable DIT encryption on remote clients without paying an unnecessary performance penalty for local, internal storage cluster communications.
Use Cases
This multi-architecture storage model aligns with complex data center infrastructure consolidation and compliance scenarios.
- Phased Enterprise Private Cloud Refactoring: Gracefully draining data out of aging vSphere 7.x/8.x legacy blocks over to modern VCF 9.1 infrastructures over a multi-month schedule without application outages.
- Multi-Tenant Clean Room Isolations: Establishing a high-density centralized storage cluster that safely feeds independent compute clusters via distinct, hardware-encrypted transport links.
- Sovereign Compliance Attestation Audits: Meeting strict zero-trust standards that require all data moving across data center rack rows to be cryptographically verified.
Alternatives
When structuring cross-cluster storage access, enterprise platform engineers evaluate this native mechanism against separate approaches.
- Forced Homogeneous Upgrades (The Cold Cutover): Keeping a strict rule where all clusters must be matching ESA architectures. This forces companies to fully buy and deploy an entirely new server fleet all at once, resulting in high CapEx and complex logistical challenges during hardware shortages.
- External Hardware Storage Gateway Overlays: Dropping in intermediate virtual appliances or external controllers to export storage blocks via standard iSCSI or NFS protocols across clusters. This adds an unnecessary management layer, bypasses native vSAN storage policy integration, and creates performance bottlenecks.
Alternative Perspective
While mixed-mode remote mounting provides an excellent bridge for migrations, keeping it as a long-term production state introduces structural operational complexities. Running a disaggregated storage model across contrasting OSA and ESA environments means that your storage performance profile will be fundamentally bounded by the weakest link. If an application VM residing on a high-speed compute host executes a write command that targets a legacy, remote OSA datastore, the application’s overall storage performance will drop down to legacy SAS/SATA limits—potentially confusing automated monitoring systems and performance engineers.
Final Thoughts
The introduction of mixed-mode remote mounting and end-to-end encryption in VCF 9.1 highlights Broadcom’s intent to treat the private cloud as a cohesive, elastic pool of resources. By allowing legacy and modern architectures to share data securely, VCF lowers the cost and friction of migrating to the next generation of software-defined infrastructure. In the capital-constrained climate of 2026, the best modernization strategy is one that allows you to transition your data at your own pace without sacrificing security.
Source
https://blogs.vmware.com/cloud-foundation/2026/05/12/vsan-storage-clusters-in-vcf-9-1