Walrus lies a simple but uncompromising invariant: every blob that has passed the Point of Availability (PoA) must remain available, regardless of how the network changes over time. The reconfiguration protocol exists to protect this guarantee. Unlike blockchains, where reconfiguration mainly concerns validator sets and small state, Walrus must safely migrate large volumes of data shards while continuing to serve reads and writes without interruption.
Reconfiguration in Walrus is triggered when the set of storage nodes changes, nodes may join, leave, be slashed, or become temporarily unavailable. During these transitions, Walrus carefully coordinates shard movement so that availability is never compromised. Blobs that have reached PoA are treated as durable commitments: the network assumes a permanent obligation to keep enough encoded fragments accessible to allow reconstruction at any time in the future.
To achieve this, Walrus relies on quorum-based guarantees and erasure coding. Before a blob reaches PoA, the system collects sufficient acknowledgements from storage nodes, proving that the data is widely distributed. Once PoA is reached, reconfiguration cannot invalidate that promise. Incoming nodes recover missing slivers from existing nodes, while outgoing nodes are required to cooperate in shard migration. If they fail to do so, recovery mechanisms ensure that shards are rebuilt from the remaining honest nodes.
Crucially, reconfiguration does not pause the system. Walrus continues to process reads and writes even as shards are being transferred in the background. This makes reconfiguration a continuous, online process rather than a disruptive event. The protocol is designed to tolerate partial failures, slow nodes, and adversarial behavior without breaking availability guarantees.
The reconfiguration protocol is Walrus way of turning a dynamic, decentralized network into a stable long-term memory layer. No matter how the set of nodes evolves, Walrus preserves its core promise: once data is declared available, it stays available.
