[jira] [Created] (HBASE-26798) balancer reported metrics and balancer logs

["Briana Augenreich (Jira)" <ji...@apache.org>]

Briana Augenreich created HBASE-26798:
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             Summary: balancer reported metrics and balancer logs 
                 Key: HBASE-26798
                 URL: https://issues.apache.org/jira/browse/HBASE-26798
             Project: HBase
          Issue Type: Improvement
    Affects Versions: 2.5.0, 2.6.0, 3.0.0-alpha-3, 2.4.11
            Reporter: Briana Augenreich
            Assignee: Briana Augenreich


Sometimes we have noticeable skew in our hbase clusters but see the balancer cannot find a better plan to resolve this skew. When trying to reason about why the StochasticLoadBalancer is not taking action and appropriately tuning costs as needed, it is often hard to quickly reason about how the published metrics  and output in the logs correlate and impact the balancer actions. It is also sometimes hard to reason about how a cost like the move cost (which doesnt show up in imbalance and is a hidden cost against every move in calculating a new plan) might be impacting the balancer effectiveness. 

 

It would be nice to include some additional information like the sumMultiplier and overallCost in the logs as well as publish the weighted imbalance metrics and rename the cost metrics to CostFunctionPercentage. Also additional logging for the state of the cost functions when an improved plan cannot be found would also be helpful. 



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