Customers have expressed interest in deploying active/active fabrics using multiple vmknics for load balancing and failover purposes. This design is motivated by and analogous to deploying multipathing options in traditional storage deployments. While this configuration is supported, there are certain scenarios (described below) where the guest OS may become unresponsive. Therefore, VMware does not recommend using this configuration for vSAN clusters below 6.7.

Partial failure of the fabric occurs when some, but not all, of the network links of a fabric are down. Due to this partial failure, a subset of the hosts in the cluster are unable to communicate with each other.

In the event of a partial failure of the fabric, all vSAN communications are redirected to the healthy fabric on the affected hosts. This process of failing over to a healthy link (on the other fabric) may take up to 90 seconds or the TCP timeout value, whichever is greater. Since the failover is not instantaneous, the guest OS on the impacted host may become unresponsive. This is dependent on how storage timeouts are handled by the guest OS. If the guest OS is stalled (becomes unresponsive), manual intervention and remediation is required to establish normal operations.

In the case of full fabric failure, the failover process is instantaneous, and therefore, there is no impact on the behavior of the guest OS.

To deploy active/active network configurations, follow these guidelines to set up the fabrics:

 

Note: These guidelines are applicable for layer-2 and layer-3 setups.