What is the minimum number of nodes needed in a cluster in order to enable Erasure Coding on a storage container configured with Replication Factor 2?
Erasure Coding (EC-X) encodes data into strips consisting of data blocks plus parity blocks, and each block in a strip must reside on a separate node to preserve node-level fault tolerance. For a Replication Factor 2 (Fault Tolerance 1) container, the smallest supported strip configuration is 2 data blocks plus 1 parity block (a 2/1 strip), which requires at least 4 nodes in the cluster so that each block of the strip—and the redundancy needed to survive a single node failure—can be placed on a distinct node. This is documented as the technical minimum node requirement to enable EC-X on an RF2 container in Nutanix's official architecture documentation (the Nutanix Bible), even though larger strip sizes (e.g., 4/1) and additional nodes are recommended for better rebuild efficiency.
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