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How many nodes are required in a SolidFire cluster for it to remain operational?

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Applies to

  • NetApp SolidFire All-Flash Array (AFA)
  • NetApp HCI Storage Nodes

Answer

How to assess if your cluster can remain online. 

Step 1: Identify remaining nodes

  • Determine how many nodes will remain online during maintenance or failure.

Step 2: Determine usable capacity per node

  • Check:
    • Number of block drives per node
    • Usable capacity per node

Step 3: Calculate total remaining capacity

  • Example:
    • Remaining nodes: 3
    • Usable capacity per node: 2.4 TB
      • Total available capacity = 3 × 2.4 TB = 7.2 TB

Step 4: Compare with used capacity

  • If:
    • Used capacity < 7.2 TB → Cluster can remain online
    • Used capacity > 7.2 TB → Cluster cannot safely operate

Ideally, there should be additional free capacity equivalent to at least one node to tolerate an unexpected node failure during maintenance.

Additional Information

Minimum node requirement (baseline):
  • A SolidFire cluster requires a minimum of 4 storage nodes to be created and operate as a cluster. [docs.netapp.com]
  • This is the minimum configuration required to provide storage services and distributed data protection.
Note that even if the cluster has the minimum required nodes, operational state during failures or maintenance depends below factors: 
  • Number of nodes remaining online:
    1. SolidFire is a distributed system, and a sufficient number of nodes must remain online for the cluster to continue operating.
    2. If too many nodes go offline (for example, a full site outage in a multi-site design), the cluster may not remain operational.
  • Available capacity vs. used capacity (critical factor)
    • The cluster can only remain online if:
    • Used Capacity < Available Capacity of Remaining Nodes
      • If the remaining nodes do not have enough usable capacity to hold existing data, the cluster cannot safely continue operations.
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