Joining 1 Node into HCI Cluster with 2 Node

Saiful Zolkipli Lv1Posted Dec-16-2025 17:22

I got question.

My customer got 1 HCI cluster with 2 nodes. And the asan running locally which is usually we do setup on network for stroage. I saw the 2 physical connections between node 1 and node 2 which are for aSan as I checked.

The question is, when I wanted to add 1 new node into the cluster, does aSan can be maintained as before which is I just make a ring topology for aSan. So 3 node connect locally. Since usually storage for HCI will connected to the network switch.

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In a 2-node Sangfor HCI cluster, it is common to see direct physical connections between Node 1 and Node 2 for aSAN traffic. This design works because there are only two nodes, so point-to-point connectivity is simple and supported.

However, when you add a 3rd node, the design should change.

Key Explanation:

aSAN does not support ring topology or full-mesh direct cabling for clusters with more than 2 nodes.

Direct node-to-node connections are only supported for 2-node clusters.

Once the cluster scales to 3 nodes or more, aSAN must use a network switch for storage communication.

Why a Network Switch Is Required for 3+ Nodes:

aSAN relies on consistent, scalable, and redundant connectivity

Ring or mesh cabling becomes:

Difficult to manage

Not scalable

Prone to failure and troubleshooting complexity

Switch-based design ensures:

Proper heartbeat communication

Stable data replication

Predictable performance

Recommended Design for 3-Node HCI Cluster:

Use dedicated storage network (preferably 10Gb)

All nodes connect their aSAN NICs to the same storage switch(es)

Recommended:

Dual switches for redundancy

Separate VLAN for aSAN traffic

Jumbo Frames (MTU 9000) enabled

Summary:

✅ 2-node cluster → Direct aSAN connection supported

❌ 3-node cluster → Ring topology not supported

✅ 3+ nodes → aSAN must be connected via network switch

Recommendation:

Before adding the third node, redesign the aSAN network using proper switching infrastructure to avoid instability and unsupported topology.
Is this answer helpful?
Muhammad Abid Lv1Posted Dec-16-2025 18:55
  
In a 2-node Sangfor HCI cluster, it is common to see direct physical connections between Node 1 and Node 2 for aSAN traffic. This design works because there are only two nodes, so point-to-point connectivity is simple and supported.

However, when you add a 3rd node, the design should change.

Key Explanation:

aSAN does not support ring topology or full-mesh direct cabling for clusters with more than 2 nodes.

Direct node-to-node connections are only supported for 2-node clusters.

Once the cluster scales to 3 nodes or more, aSAN must use a network switch for storage communication.

Why a Network Switch Is Required for 3+ Nodes:

aSAN relies on consistent, scalable, and redundant connectivity

Ring or mesh cabling becomes:

Difficult to manage

Not scalable

Prone to failure and troubleshooting complexity

Switch-based design ensures:

Proper heartbeat communication

Stable data replication

Predictable performance

Recommended Design for 3-Node HCI Cluster:

Use dedicated storage network (preferably 10Gb)

All nodes connect their aSAN NICs to the same storage switch(es)

Recommended:

Dual switches for redundancy

Separate VLAN for aSAN traffic

Jumbo Frames (MTU 9000) enabled

Summary:

✅ 2-node cluster → Direct aSAN connection supported

❌ 3-node cluster → Ring topology not supported

✅ 3+ nodes → aSAN must be connected via network switch

Recommendation:

Before adding the third node, redesign the aSAN network using proper switching infrastructure to avoid instability and unsupported topology.
Zonger Lv5Posted Dec-17-2025 03:56
  
In a two-node HCI deployment aSAN can run over direct attached (point-to-point) links between the nodes but when you add a third node this design is no longer supported or scalable because a ring or full-mesh of direct connections becomes complex and unreliable therefore, aSAN should be migrated to a switched network topology using dedicated storage network switches so all three nodes connect through the switch, ensuring proper redundancy, bandwidth management and supported operation.
Newbie871459 Posted Dec-17-2025 14:36
  
No, you should not keep a direct “ring” or point-to-point aSAN topology when adding a 3rd node.
In a 2-node HCI setup, direct-connect (point-to-point) for aSAN/storage traffic is common and supported. However, once you add a 3rd node, a ring or mesh of direct connections is not recommended and usually unsupported by HCI vendors.

For 3+ nodes, aSAN/storage traffic should be connected through redundant network switches (typically 2 switches) using a dedicated storage VLAN. This provides proper scalability, redundancy, and predictable latency.

So when adding the new node, migrate the aSAN network from direct-connect to switch-based networking, then join the node to the cluster.
Saiful Zolkipli Lv1Posted Dec-29-2025 11:40
  
Thank you Sir for sharing your answers. Thats help me a lot.

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