palashc commented on code in PR #21: URL: https://github.com/apache/phoenix-site/pull/21#discussion_r3269177765
########## app/pages/_docs/docs/_mdx/(multi-page)/features/high-availability.mdx: ########## @@ -0,0 +1,187 @@ +--- +title: "High Availability" +description: "Active/active and active/standby Phoenix client wiring across two HBase clusters, with graceful failover that lets in-flight readers drain while writes are blocked." +--- + +Phoenix High Availability (HA) lets a JDBC client transparently target a pair +of HBase clusters that mirror the same Phoenix schema, so an operator-driven +or fault-driven failover never requires the application to restart, reconnect, +or rewrite URLs. + +Phoenix 5.3.1 adds **graceful failover** — an intermediate `ACTIVE_TO_STANDBY` +role that lets writes drain while readers keep working — plus support for +HBase's `MASTER` and `RPC` connection registries +([PHOENIX-7493](https://issues.apache.org/jira/browse/PHOENIX-7493), +[PHOENIX-7495](https://issues.apache.org/jira/browse/PHOENIX-7495), +[PHOENIX-7586](https://issues.apache.org/jira/browse/PHOENIX-7586)). + +## Concepts [#ha-concepts] + +An **HA group** is a named tuple of two HBase clusters and an HA policy, +shared by every client that participates. The current role of each cluster +lives in a JSON record in ZooKeeper, replicated to both clusters' ZK +ensembles and watched by the client; role changes are picked up +automatically. + +### Cluster roles + +| Role | Clients can connect? | Meaning | +| ------------------- | :------------------: | ------------------------------------------------------------------------------------------------------------------------------------- | +| `ACTIVE` | yes | Cluster is serving live reads and writes. | +| `STANDBY` | yes | Cluster is reachable but not the current primary; FAILOVER clients refuse to bind to it. | Review Comment: done -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
