As I have written in a reply above but that is kind of lost in the tread: I have set dfs.replication at 2 but this process time has not changed at all. How could I change my configuration to avoid this hotspot issue you have talked about.
As Kevin has advised I have also upped: hbase.hstore.blockingStoreFiles to 100 hbase.hregion.memstore.block.multiplier to 7 hbase.hregion.memstore.flush.size to 256 MB hbase.regionserver.optionallogflushinterval to 30s These changes did not bring any significant evolution in speed. My cluster is 3 ubuntu machines: 2 cores 4 threads 3.4+ GHz with 16gb ram thanks for everyones help
