I dont plan on working on this in the short term, but the idea is to extend region ownership to have two modes. Each region has one primary region server and N slave region servers. The slaves would follow the master (probably by streaming the relevant HLog entries directly from it) and be able to serve stale reads. The benefit is twofold: (a) provides the ability to spread read load, (b) enables very fast region failover/rebalance since the memstore is already nearly up to date on the slave RS.
|Summary||Add read-only region replicas (slaves) for availability and fast region recovery||Coprocessors: Add read-only region replicas (slaves) for availability and fast region recovery|