The procedure in this section prepares the cluster for stretching. After these steps, you must follow the VMware Validated Design documentation to complete stretching your cluster.

  • Download the Deployment for Multiple Availability Zones document and read it to understand the requirements.

  • Ensure that you have a vSAN Enterprise license, which is required for stretching a cluster.

  • The management VLAN between the two availability zones must be stretched.

  • All VMs on an external network must be on a virtual wire. If they are on a VLAN, that VLAN must be stretched as well.

  • Each availability zone must have its own vMotion, vSAN, and VXLAN networks.

  • The vMotion, vSAN, and VXLAN networks require L3 routing between the availability zones. vSAN networks must also have L3 routing to the vSAN network of the witness host.

  • The VLAN IDs must be identical on both availability zones.

  • Each stretched cluster requires a vSAN witness appliance in a third party location. The maximum RTT on the witness is 200ms.

  • If you are stretching a cluster in a VI workload domain, you must stretch the management domain cluster first. vCenter Servers for all workload domains are in the management domain. Hence, you must protect the management domain to ensure that you can access and manage the workload domains.

  • Ensure that you have enough hosts such that there is an equal number of hosts on each availability zone. This is to ensure that there are sufficient resources in case an availability zone goes down completely.

  • TCP port and UDP Ports needs to be open for witness traffic between the witness host and the vSAN cluster data nodes. See KB article 52959.

Cloud Foundation Networks

Network Name

Connectivity to AZ2

Minimum MTU

Maximum MTU

vSAN

L3

1500

9000

vMotion

L3

1500

9000

VXLAN (VTEP)

L3

1600

9000

Management

L2

1500

9000

Witness Management

L3

1500

9000

Witness vSAN

L3

1500

9000