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https://issues.apache.org/jira/browse/KUDU-3199?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mahesh Reddy updated KUDU-3199:
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Summary: kudu cluster rebalancer: add a flag to ignore all defined
locations (was: kudu cluster rebalaner: add a flag to ignore all defined
locations)
> kudu cluster rebalancer: add a flag to ignore all defined locations
> -------------------------------------------------------------------
>
> Key: KUDU-3199
> URL: https://issues.apache.org/jira/browse/KUDU-3199
> Project: Kudu
> Issue Type: Improvement
> Components: CLI
> Reporter: Alexey Serbin
> Priority: Major
> Labels: CLI, maintainability, usability
>
> When the location-aware rebalancer was designed, it was assumed that the tool
> should always honor the partitioning of the cluster defined by locations
> whatever the partitioning was. The only options considered were to run the
> process excluding particular rebalancing phases:
> * correction of placement policy violations ({{\-\-disable_policy_fixer}})
> * inter-location rebalancing, i.e. rebalancing across different locations
> ({{\-\-disable_cross_location_rebalancing}})
> * intra-location rebalancing, i.e. rebalancing within a location
> ({{\-\-disable_intra_location_rebalancing}})
> As it turns out, there are use cases when people want to run the rebalancer
> on a location-aware cluster ignoring the location-awareness specifics. Those
> cases are:
> # The locations are defined by some higher-level cluster orchestration
> software, and people are reluctant to disable the location-awareness for Kudu
> specifically (i.e. providing an alternative script for
> {{\-\-location_mapping_cmd}}), but want to even out the distribution of
> replicas.
> # Having just two locations defined for some time. Even if it's a
> transitional phase (e.g., awaiting for a new zone/rack/datacenter to be added
> 'soon'), it could take some time.
> For both cases, there is a workaround if every location has the same number
> of tablet servers: run the rebalancer tool with the
> {{\-\-disable_policy_fixer}} flag. However, this workaround isn't applicable
> if there is difference in the number of tablet replicas per location, and no
> combination of flags could make the location-aware rebalancer run as it there
> were no locations defined.
> Let's add a new flag for the {{kudu cluster rebalance}} CLI tool to make it
> run on a location-aware cluster as if no locations were defined. Of course,
> the flag should be {{off}} by default.
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