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https://issues.apache.org/jira/browse/HDDS-5526?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Siddhant Sangwan updated HDDS-5526:
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Summary: ContainerBalancer#checkConditionsForBalancing pre-emptively checks
iteration limits. (was: ContainerBalancer#checkConditionsForBalancing can use
container size for checking iteration limits.)
> ContainerBalancer#checkConditionsForBalancing pre-emptively checks iteration
> limits.
> ------------------------------------------------------------------------------------
>
> Key: HDDS-5526
> URL: https://issues.apache.org/jira/browse/HDDS-5526
> Project: Apache Ozone
> Issue Type: Sub-task
> Components: SCM
> Reporter: Siddhant Sangwan
> Priority: Minor
>
> ContainerBalancer#checkConditionsForBalancing is used to check whether the
> max size to move or max datanodes to involve limits have been reached.
> Currently, ContainerBalancer#doIteration uses this method before finding a
> ContainerMoveSelection for a source datanode. Since the check is performed
> before selecting the next container to move, the configuration
> {color:#172b4d}OZONE_SCM_CONTAINER_SIZE {color}(default is 5GB) is used to
> predetermine if:
> sizeMovedPerIteration + configured container size >=
> maxSizeToMovePerIteration.
> This check will cause the current iteration to stop in cases like:
> maxSizeToMovePerIteration = 100GB, sizeMovedPerIteration = 96GB, and
> {color:#172b4d}OZONE_SCM_CONTAINER_SIZE{color} {color:#172b4d}= 5GB. {color}
> {color:#172b4d}On one hand the current implementation can avoid extra work by
> not letting balancer continue when we are very close to the limit. On the
> other hand, because of this implementation, we will never reach the limit.
> This Jira tracks if it's better to check conditions using container size in
> ContainerBalancer#checkConditionsForBalancing after having found a
> ContainerMoveSelection in ContainerBalancer#doIteration.{color}
> Another solution is to allow one container move before checking the limit.
> The downside is that if the limits are really low (size lesser than 5GB,
> number of datanodes lesser than 2), we will fail to respect them. However, I
> can't think of any use-case for setting such low limits.
>
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