Deploying a VMware vSAN Stretched Cluster in an Existing VMware Cloud Foundation Workload Domain
As organizations continue expanding their infrastructure across multiple locations, maintaining high availability and disaster resilience becomes critical. One of the most effective solutions for achieving this in a VMware environment is deploying a VMware vSAN Stretched Cluster within VMware Cloud Foundation (VCF).
In this article, we will walk through the process of expanding an existing VMware Cloud Foundation workload domain using a vSAN stretched cluster architecture.
What is a vSAN Stretched Cluster?
A vSAN stretched cluster is a configuration that distributes cluster nodes across two geographically separated sites while maintaining a single logical cluster. This architecture provides:
- High availability across sites
- Protection against site failure
- Continuous workload availability
- Simplified disaster recovery
Within VMware Cloud Foundation, stretched clusters can be deployed for workload domains to improve business continuity and resilience.
Prerequisites
Before starting the deployment, ensure the following requirements are met:
- Existing VMware Cloud Foundation environment
- Operational SDDC Manager
- Configured workload domain
- Layer 2 and Layer 3 network connectivity between sites
- Proper DNS and NTP configuration
- Low latency network connectivity between sites
- vSAN compatible hardware
- Dedicated networks for:
- vSAN traffic
- vMotion traffic
- Management traffic
Step 1 – Create a Network Pool for Site-B
The first step is to create a new network pool in SDDC Manager for the secondary site (Site-B).
Navigate to:
SDDC Manager → Administration → Network Settings → Create Network Pool
While creating the network pool, configure:
- VLAN IDs
- MTU size
- Network ranges
- Subnet masks
- Default gateways
The following networks are typically configured:
- vSAN Network
- vMotion Network
Proper network planning is essential to ensure optimal performance and seamless communication between cluster nodes.
Step 2 – Commission Hosts into SDDC Manager
After the network pool is created, the next step is to commission the ESXi hosts that will participate in the stretched cluster.
During host commissioning:
- Assign management IP addresses
- Validate DNS and NTP settings
- Verify hardware compatibility
- Confirm network connectivity
Once validation completes successfully, the hosts become available for workload domain expansion.
Step 3 – Add Hosts to the Workload Domain Cluster
Now navigate to:
SDDC Manager → Workload Domains
Select the target workload domain cluster where the stretched cluster hosts will be added.
From the cluster menu:
- Click the three-dot menu
- Select Add Host
You will now see the list of available commissioned hosts.
Select the required hosts and proceed to the next step.
Step 4 – Configure Distributed Switch and Uplinks
During the host addition process, you must map the hosts to the appropriate distributed virtual switch (VDS).
Configure:
- Distributed Switch assignment
- Physical uplinks
- Network adapters
- Traffic separation policies
Ensure that vSAN and vMotion traffic are properly isolated according to VMware best practices.
Step 5 – Validate Configuration
Before deployment begins, VMware Cloud Foundation performs an automated validation process.
The validation checks include:
- Network connectivity
- VLAN consistency
- DNS resolution
- Storage compatibility
- vSAN readiness
- Cluster health
Review all settings carefully and resolve any warnings or errors before proceeding.
Once validation completes successfully, click Next to continue.
Step 6 – Verify Hosts in vCenter Server
After deployment finishes, log in to the workload domain vCenter Server.
Verify that:
- Newly added hosts appear in the cluster
- Networking is functioning correctly
- vSAN storage is operational
- Cluster health is healthy
At this stage, the stretched cluster nodes should be fully integrated into the workload domain.
Step 7 – Configure vSAN Fault Domains
The final step is configuring fault domains for site awareness.
Navigate to:
Cluster → Configure → vSAN → Fault Domains
Create separate fault domains for:
- Site-A
- Site-B
Fault domains ensure that vSAN maintains data availability and redundancy across both locations.
This configuration enables VMware vSAN to intelligently place data replicas across sites for maximum resilience.
Benefits of vSAN Stretched Clusters in VCF
Deploying a stretched cluster in VMware Cloud Foundation provides several advantages:
- Improved disaster recovery capabilities
- Higher application availability
- Simplified infrastructure management
- Integrated lifecycle management
- Automated deployment and validation
- Better business continuity
VMware vSAN stretched clusters offer a powerful solution for organizations requiring high availability across multiple sites. By leveraging VMware Cloud Foundation automation and lifecycle management capabilities, administrators can deploy resilient infrastructure with reduced operational complexity.
Careful planning of networking, host placement, and fault domains is essential for a successful stretched cluster deployment.
As businesses continue adopting hybrid and multi-site architectures, VMware vSAN stretched clusters remain a key technology for ensuring infrastructure resilience and continuous service availability
