Jason, > Andrew, when you say this: > > > Because HBase is a DOT it can provide strongly consistent > > and atomic operations on rows, because rows exist in only > > one place at a time. > > This excludes the use of HBase replication?
Yes. With the new replication feature of 0.92 edits are streamed from one cluster to another. Row mutations will be consistent/atomic as they are applied at the target, but of course the replication stream may lag for a number of reasons. Therefore the row data according to the view of each cluster may be different. > I'm curious as to where HBase replication places the duplicate(?) > region blocks in HDFS? The edits are streamed from the WAL. WALs are rolled per usual but are kept perhaps for a longer period of time; until all of their replication scoped edits have been streamed to the target cluster. > Also currently is there pass the baton failover when a replicated > region master fails? Yes. Via mechanisms mediated by ZooKeeper. But J-D could say more here. - Andy
