The 2-Node Cluster Dilemma: Gateway Arbitration vs. a 3-Node Minimum for Enterprise Production?

When designing a new Sangfor HCI architecture, we often face budget constraints that push clients toward a 2-Node Cluster Deployment. Sangfor elegantly supports this by using Gateway Arbitration (filling in the Gateway IP during virtual storage initialization) to identify split-brain scenarios and determine which node remains active if a cluster heartbeat breaks.

However, looking at the structural hardware layer, a 3-Node Cluster introduces a dedicated Storage Network Interface Switch topology where voting quorum is absolute, and data rebuild limits are far more forgiving.

Let's look at the mathematical reality of Virtual Storage Available Capacity Optimization:

• For a 2-Copy Policy, the formula is: Total Data Disk Size / 2 * 85% = Available Storage.
• If a single node fails in a 2-node cluster, your redundancy is entirely gone until hardware replacement arrives, whereas a 3-node cluster can still maintain structural balancing.

  
  

  
  
  
  

My questions to the community:

• Do you ever sign off on a 2-Node cluster with Gateway Arbitration for core enterprise production databases, or do you limit it strictly to Edge/ROBO sites?
• If a network flap occurs and the 2-Node cluster triggers arbitration, have you noticed any performance degradation on the node that handles the forced VM failover?
• What is your standard policy for adjusting the optimized disk grouping (Cache SSD to Data HDD ratio) when initializing a minimal 2-node footprint?

  
  

  
  
  
  

No,
. For core enterprise production databases, I generally recommend a 3-node cluster whenever budget allows. A 2-node cluster with Gateway Arbitration is a solid design for edge and branch deployments, but it operates with much less margin for error once a node fails.
. There isn't one perfect ratio, but for small 2-node deployments I generally prioritize cache more aggressively than I would in larger clusters.

. No,
. For core enterprise production databases, I generally recommend a 3-node cluster whenever budget allows. A 2-node cluster with Gateway Arbitration is a solid design for edge and branch deployments, but it operates with much less margin for error once a node fails.
. There isn't one perfect ratio, but for small 2-node deployments I generally prioritize cache more aggressively than I would in larger clusters.