# How does PD select/filter a `Region`?
+ `Region` is hot
  + Controlled by **`hotRegionScheduler`**
+ `Region` is unhealthy
  + Need fix by **`ReplicaChecker`** and **`RuleChecker`**
+ `Region` is recently splitted **`(MergeChecker)`**
+ No `store` to replace `peer`
+ Check the metrics of the corresponding `Scheduler/Checker` to understand why the `Region` is not available

![`smart`](OperatorFindARegion_aa_001_20221024.png)

![`smart`](BalanceRegionMergeRegion_aa_001_20221024.png)

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