makes a lot of sense. thanks Dave,
Jason On Thu, Jun 27, 2013 at 10:26 AM, Dave Wang <d...@cloudera.com> wrote: > Jason, > > HBase replication is for between two HBase clusters as you state. > > What you are seeing is merely the expected behavior within a single > cluster. DFS replication is not involved directly here - the shell ends up > acting like any other HBase client and constructing the scan the same way > (i.e. finding the right region servers to do the scan by contacting ZK, > region server serving .META., issuing the scan requests to the proper RSes, > etc.). It doesn't matter where you are running the client from. > > There is no "replicating HBase tables" within the same cluster - you're > just accessing the same table from different clients. > > Hope this helps, > > - Dave > > > On Thu, Jun 27, 2013 at 7:04 AM, Jason Huang <jason.hu...@icare.com> > wrote: > > > Hello, > > > > I am a bit confused how configurations of hbase replication and dfs > > replication works together. > > > > My application deploys on an HBase cluster (0.94.3) with two Region > > servers. The two hadoop datanodes run on the same two Region severs. > > > > Because we only have two datanodes, dfs.replication was set to 2. > > > > The person who configured the small cluster didn't explicitly set the > hbase > > replication configs, which includes: > > > > (1) in ${HBASE_HOME}/conf/hbase-site.xml, hbase.replication is not set. I > > think the default value is "false" according to > > http://hbase.apache.org/replication.html. > > > > (2) in the table,Replication_Scope is set to 0 (by default). > > > > However, even without setting hbase.replication and replication_scope, it > > appears that the tables are duplicated in the two Region servers (as I > can > > go to the shells of these two region servers and find the duplicate rows > > from a scan). > > > > My question is - does the default dfs replication takes care of > replicating > > hbase tables within the same cluster so we don't need to set up the hbase > > replication configs? And only when we need to replicate hbase from one > > cluster to another cluster should we set up the hbase replication configs > > (1) and (2) above? > > > > thanks! > > > > Jason > > >