2011/5/6 pob <[email protected]> > Hello, > > > I set cluster of 4 nodes with hdfs + hbase (1 node - namenode, hbase > master, > zookeeper and three remains with datanode + regionserver). > > I was trying to test maximal throughput of write operation - with yahoo > ycbs. I got max 25000op/s while inserting 1KB data (1row with one column). > > > Whats really strange for me is that i run same test with same configuration > once with RF=1, then RF=3 on HDFS. The results was kind of same. Why? > Replication should add overhead..., so how it could be same? >
By default ycsb disables autoflush and increases write buffer size to large amount. My guess is this could be the reason you do not see much difference in when changing replication. Also, you might want to increase record size and then look at real replication overhead. > > Then I double cluster with 3 more datanodes and regionservers. I run same > test and I got the same op/s like with 3 nodes. Why? Isnt the point of > distributed DB to scale? so dobule nodes ~half double write speed? > > > To omit any client bottleneck, I wrote simple inserter and was trying > inserting from 3 different nodes into cluster, doesnt help (i pre-split > regions. was trying to get evenly load, during monitoring it with jconsole > the load was about 25:50:25). But the results was same like with one > client. > > > I found there is performance util with hbase, PerformanceEvaluation.java > but i cant find any information how to compile it. > > > Thanks for any ideas. > -- Have a Nice Day! Lohit
