{"id":6070,"date":"2018-12-01T18:26:57","date_gmt":"2018-12-02T02:26:57","guid":{"rendered":"https:\/\/www.couchbase.com\/blog\/?p=6070"},"modified":"2025-06-13T20:46:24","modified_gmt":"2025-06-14T03:46:24","slug":"understanding-xdcr-part-1","status":"publish","type":"post","link":"https:\/\/www.couchbase.com\/blog\/understanding-xdcr-part-1\/","title":{"rendered":"Understanding Cross Data Center Replication (XDCR) – Part 1"},"content":{"rendered":"

If you have any familiarity with Couchbase, you definitely know XDCR<\/a>. If you use Couchbase for any of your applications, you are very likely using XDCR. I wouldn\u2019t be wrong if I said, XDCR is indeed one of our customers\u2019 most loved products. If you are now interested in learning what makes XDCR so awesome, you are in the right place, please continue reading. In contrary, if you have no idea about what am saying, well this is your opportunity to learn about it.<\/span><\/p>\n

Replication is the key to the effectiveness of distributed systems to provide enhanced performance, high availability and fault tolerance. XDCR is a highly performant replication technology used to replicate data between two Couchbase clusters. This is complementary to the intra-cluster replication. XDCR provides asynchronous replication and maintains data consistency across sites via eventual consistency.This implies, as soon as a single copy of mutation is executed, acknowledgements are sent to the applications and eventually data becomes consistent across different clusters in the topology.<\/span><\/p>\n

Core principles behind this technology <\/b><\/p>\n

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  1. Highly performant :<\/b> XDCR is highly performant replication system operating at the speed of network and memory with very low latency. Replication is memory to memory. <\/span><\/li>\n
  2. Independently scalable system :<\/b> XDCR has a peer to peer architecture where clusters can be added or removed and every cluster in the topology can be scaled up or down without impacting other clusters.<\/span><\/li>\n
  3. Infrastructure agnostic :<\/b> XDCR can be used to replicate data between any two couchbase clusters irrespective of their deployment platform as bare metal, VMs, private cloud, public cloud, hybrid or containers. <\/span><\/li>\n
  4. Topology aware : <\/b>\u00a0XDCR is topology aware, as nodes are added to \/ removed from clusters, system adjusts and manages replication accordingly, without any manual intervention.<\/span><\/li>\n
  5. Simplified setup and administration:<\/b> XDCR can be set up in <15 secs, between any two Couchbase clusters. Once set up, the documents are continuously synchronized between source and target. It operates without any manual intervention even during topology changes like failover or rebalance.<\/span><\/li>\n
  6. Flexible topology :<\/b> Unidirectional, bidirectional, hub & spoke, ring, mesh etc., any complex topology can be set up. <\/span><\/li>\n
  7. Resilient :<\/b> Incase of any network failures, XDCR can resume replication from where it was interrupted. XDCR also continuously retries until the replication is successful.<\/span><\/li>\n<\/ol>\n

    XDCR under the hood<\/b><\/p>\n

    To familiarize yourself with Couchbase server architecture, please listen to this\u00a0talk<\/a>.<\/span><\/p>\n