In HBase 0.90.0 there is a new "retain assignment" configuration parameter that makes it so your cluster keeps the same region assignment between full cluster restarts. It is ON by default.
> -----Original Message-----
> From: Tao Xie [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, January 20, 2011 6:37 PM
> To: [EMAIL PROTECTED]
> Subject: performance regression after hbase restart
> hi, I know regions will be reassigned when hbase cluster restarts. My
> regionserver and my datanode sit on same physical node. So in my tests after
> I restart hbase cluster, performance number drops, I guess this is due to data
> locality problem. But in a further experiment, I increase the replication factor
> to cluster size ( I have 8 nodes). After restart and major compaction, the
> performance still cannot catch up with the best scenario. I checked datanode
> log, most hdfs read has same src and dest node.
> Anyone give me some hints on this? I wonder if anything happens during
> region reassignment.