Hello @mingtian
Note that Debug Logging won't ensure the Balancer would perform Region Movement, rather the same would confirm if Balancer is running yet the same isn't moving any Region owing to CostFactor. Example: I ensured 1 RegionServer didn't had any Region by RegionMovement & triggered a Balancer, which showed [1] & trigger a Region Movement (Note "Found A Solution That Moves 1 Region"). After the 1st Balancer is Completed, I triggered a 2nd Balancer, which printed [2], wherein the DEBUG report "Skipping Load Balancing".
I believe your Team would see [2] i.e. Balancer is Skipping any Load Balancing owing to Cost Factor. As such, Your Team can consider the fact that HBase is rejecting Region Movement owing to the fact that any new Region-Movement is "Costlier" than Current Region Placement. Tweaking [3] Cost Parameters including setting "hbase.master.loadbalance.bytable" to "true" should help trigger a Balancer for your Team.
Regards, Smarak
[1]
2023-01-18 06:38:33,290 INFO org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer: Finished computing new moving plan. Computation took 95 ms to try 7200 different iterations. Found a solution that moves 1 regions; Going from a computed imbalance of 0.4961380973335763 to a new imbalance of 0.020487264673311183. funtionCost=RegionCountSkewCostFunction : (multiplier=500.0, imbalance=0.0); PrimaryRegionCountSkewCostFunction : (not needed); MoveCostFunction : (multiplier=7.0, imbalance=0.3333333333333333, need balance); ServerLocalityCostFunction : (multiplier=25.0, imbalance=0.0); RackLocalityCostFunction : (multiplier=15.0, imbalance=0.0); TableSkewCostFunction : (multiplier=35.0, imbalance=0.0); RegionReplicaHostCostFunction : (not needed); RegionReplicaRackCostFunction : (not needed); ReadRequestCostFunction : (multiplier=5.0, imbalance=1.0, need balance); WriteRequestCostFunction : (multiplier=5.0, imbalance=1.0, need balance); MemStoreSizeCostFunction : (multiplier=5.0, imbalance=0.0); StoreFileCostFunction : (multiplier=5.0, imbalance=0.0);
[2]
2023-01-18 06:39:05,365 INFO org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer: Cluster wide - skipping load balancing because weighted average imbalance=0.013858568086431631 <= threshold(0.025). If you want more aggressive balancing, either lower hbase.master.balancer.stochastic.minCostNeedBalance from 0.025 or increase the relative multiplier(s) of the specific cost function(s). functionCost=RegionCountSkewCostFunction : (multiplier=500.0, imbalance=0.0); PrimaryRegionCountSkewCostFunction : (not needed); MoveCostFunction : (multiplier=7.0, imbalance=0.0); ServerLocalityCostFunction : (multiplier=25.0, imbalance=0.0); RackLocalityCostFunction : (multiplier=15.0, imbalance=0.0); TableSkewCostFunction : (multiplier=35.0, imbalance=0.0); RegionReplicaHostCostFunction : (not needed); RegionReplicaRackCostFunction : (not needed); ReadRequestCostFunction : (multiplier=5.0, imbalance=0.6685715976063684, need balance); WriteRequestCostFunction : (multiplier=5.0, imbalance=1.0, need balance); MemStoreSizeCostFunction : (multiplier=5.0, imbalance=0.0); StoreFileCostFunction : (multiplier=5.0, imbalance=0.0);
[3] StochasticLoadBalancer (Apache HBase 3.0.0-alpha-4-SNAPSHOT API)
