Storage Migration Guide — Data Center Infrastructure

vSAN to External Storage Migration: A Decoupling Guide for Enterprise Infrastructure

A practical guide for enterprise architects planning the migration from VMware vSAN to disaggregated external storage with Pure Storage FlashArray and Nutanix AHV, covering architecture decisions, data migration strategies, and risk mitigation.

22 min read
Storage Migration vSAN Pure Storage Nutanix AHV Infrastructure Modernization

A vSAN-to-external-storage migration should never be attempted as a single cutover event. The approach is phased, with validation gates at each stage and production protection throughout. The planning phase determines whether the migration succeeds or becomes a months-long recovery effort.

Start with comprehensive inventory and dependency mapping. Catalog the vSAN environment: cluster topology, storage policies, VM-to-host affinity rules, capacity utilization, and I/O profiles. Map dependencies between VMs — which workloads can move independently and which need to move together. Identify any vSAN-specific features in use (stretched clusters, deduplication policies, encryption) that need equivalent configuration on the target.

Design the Pure FlashArray configuration based on the workload analysis: volume layout, host groups, replication policies, and connectivity protocol selection. Size the Arista storage fabric for the aggregate throughput requirements. Design the Nutanix cluster topology with UCS compute nodes and define Intersight server profiles for stateless operation.

The migration timeline needs to balance risk reduction with licensing costs. Longer migration timelines reduce technical risk but increase the period of dual licensing costs. Align your migration phases with VMware renewal dates to minimize overlap. A well-executed migration typically completes the bulk of workload movement in 3–6 months, with stragglers moving to AWS EVS rather than holding up the decommissioning timeline.

Key Takeaways

1
vSAN migrations require simultaneous storage and compute migration, unlike external storage environments where these can be decoupled
2
Disaggregated architecture with Pure FlashArray and Nutanix AHV provides independent scaling and eliminates forced coupling
3
Phased migration with parallel infrastructure deployment is essential — never attempt vSAN decoupling as a single cutover event
4
Storage protocol selection should prioritize operational familiarity over peak performance benchmarks
5
Post-migration operational complexity often justifies co-managed services rather than building internal expertise across all disaggregated layers
6
Migration timeline should align with VMware licensing renewal dates to minimize dual licensing costs

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FAQs
How long does a vSAN-to-external-storage migration typically take?

The full program — from initial assessment through final vSAN decommissioning — typically runs 4–9 months depending on the size of the environment and the number of workloads. The architecture and pilot phases take 6–8 weeks. Bulk migration runs 2–4 months. Stragglers that need AWS EVS add additional time but don't block vSAN decommissioning for the majority of the estate.

Can we keep some workloads on vSAN while migrating others?

Yes — this is the expected approach. The migration is phased, and the vSAN cluster continues running during the transition. However, be aware that removing hosts from a vSAN cluster triggers data rebuilds, so the decommissioning sequence needs to be planned around vSAN's capacity and rebuild requirements.

What happens to vSAN stretched cluster configurations?

Stretched vSAN clusters — which span two sites for synchronous replication — are replaced by Pure FlashArray's built-in synchronous replication (ActiveCluster) between two arrays. This provides equivalent site-level resilience with simpler operations and without the network sensitivity of vSAN stretched clusters.

Do we need Fibre Channel for Pure Storage, or can we stay on Ethernet?

Pure FlashArray supports both Fibre Channel and Ethernet-based protocols. Since vSAN environments are already Ethernet-based, the natural path is to stay on Ethernet — using NVMe-oF, NVMe/TCP, or iSCSI over an Arista deep-buffer fabric. This avoids introducing a separate SAN infrastructure and keeps the operational model unified.

How does IVI handle this type of migration?

vSAN decoupling is part of the AIM (Aegis Infrastructure Modernization) program. IVI designs the target architecture, executes the migration in phased waves, validates performance at each stage, and transitions the environment into Aegis co-managed operations for ongoing lifecycle governance. This is a controlled, structured program — not a weekend project.

Planning a vSAN to External Storage Migration?

IVI's AIM program provides end-to-end support for vSAN decoupling — from assessment and architecture design through migration execution and ongoing operations.

Start a vSAN Assessment