Replication

Replication is the process of creating and maintaining multiple copies of an entity across space and time. In biological contexts, replication refers to the duplication of an organism's genome, allowing cells to divide and offspring to inherit genetic information. Most cellular DNA replication is semi-conservative, producing two daughter molecules from one parent molecule. The process begins at specific origins of replication, with helicase unwinding the DNA, primase laying down RNA primers, and DNA polymerases extending new strands. The leading strand is synthesized continuously; the lagging strand is synthesized in short segments called Okazaki fragments that are later joined. Fidelity is ensured by proofreading and mismatch repair, and replication is coordinated with the cell cycle. Telomeres protect chromosome ends and lagging-strand synthesis poses specific challenges, addressed by telomerase in some cell types.

In information technology, replication is maintaining copies of data across multiple machines or locations to improve availability, durability, and performance. Replication can be synchronous, with updates committed on all replicas before a response is returned, or asynchronous, with replication occurring after the primary writes. Architectures include single-master, multi-master, and distributed configurations. Consistency models range from strong consistency to eventual consistency; many systems rely on consensus protocols such as Paxos or Raft to coordinate updates. Practical considerations include latency, bandwidth, conflict resolution, and recovery after failures. Replication underpins databases, file systems, content delivery networks, and disaster recovery and is a central concern in distributed systems design.