szetszwo commented on code in PR #9580:
URL: https://github.com/apache/ozone/pull/9580#discussion_r2669395340
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hadoop-hdds/docs/content/feature/multi-raft-support.md:
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@@ -69,6 +69,64 @@ Ratis handles concurrent logs per node.
This property is effective only when the previous property is set to 0.
The value of this property must be greater than 0.
+### Calculating Ratis Pipeline Limits
+
+The target number of open, FACTOR_THREE Ratis pipelines is controlled by three
properties that define the maximum
+number of pipelines in the cluster at a cluster-wide level, datanode level,
and metadata disk level, respectively.
+SCM will create pipelines until the most restrictive limit is met.
+
+1. **Cluster-wide Limit (`ozone.scm.ratis.pipeline.limit`)**
+ * **Description**: An absolute, global limit for the total number of
open, FACTOR_THREE Ratis pipelines
+ across the entire cluster. This acts as a final cap on the total
number of pipelines.
+ * **Default Value**: `0` (which means no global limit is enforced by
default).
+
+2. **Datanode-level Fixed Limit (`ozone.scm.datanode.pipeline.limit`)**
+ * **Description**: When set to a positive number, this property defines
a fixed maximum number of pipelines for
+ every datanode. This is one of two ways to calculate a cluster-wide
target.
+ * **Default Value**: `2`
+ * **Calculation**: If this is set, the target is `(<this value> *
<number of healthy datanodes>) / 3`.
Review Comment:
```md
* **Cluster-wide Limit Calculation**: If this property is set,
the number of pipelines in the cluster is in addition limited by
`(<this value> * <number of healthy datanodes>) / 3`.
```
(revised)
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