Nonreplicated

Nonreplicated refers to data, state, or services that are stored or operated on a single node without automatic duplication across multiple nodes. In a nonreplicated design, there is no built-in replication factor and no multi-node consensus required to maintain the primary copy. This contrasts with replicated systems that maintain multiple copies to improve fault tolerance and availability.

Nonreplicated components can offer lower write latency and simpler consistency since there is only one copy to coordinate. However, they sacrifice fault tolerance and availability in the face of node failures and partitions, because data loss is possible if the node crashes and there are no replicas. Durability depends on the node’s storage and any external backups or snapshots used to recover data.

Common contexts include single-node databases such as SQLite used as a local store, ephemeral in-memory caches, or service-specific state that is persisted to external durable storage rather than replicated across machines. Nonreplicated design is often appropriate for small-scale applications, development and testing environments, or portions of a system where data is transient or externally backed up.

To mitigate risk, operators employ external backups, regular snapshots, and disaster-recovery plans. In distributed architectures that require high availability, nonreplicated components are typically restricted to noncritical data or to parts of the system where replication would add unnecessary overhead.

See also: replication, replication factor, durability, consistency, fault tolerance, CAP theorem, sharding.