[docs] clarify backend_load_capacity_coeficient behavior (#3364)

## Summary
- verify #2303 is still open/conflicted and the coefficient explanation
is still missing
- clarify that when `backend_load_capacity_coeficient` is set to a valid
value (`0.0`~`1.0`), `capacityCoefficient` uses that fixed value
- keep the existing dynamic adjustment explanation as the fallback
behavior when the parameter is not set
- apply consistently to EN + ZH docs for `current`, `version-2.1`,
`version-3.x`, and `version-4.x`

## Reference
- redoes issue intent from #2303

Author: dataroaring

docs/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -206,7 +206,7 @@ Similarly, replica balancing ensures that a copy of the same table will not be d
 
 We use Cluster LoadStatistics (CLS) to represent the load balancing of each backend in a cluster. Tablet Scheduler triggers cluster equilibrium based on this statistic. We currently calculate a load Score for each BE as the BE load score by using **disk usage** and **number of copies**. The higher the score, the heavier the load on the BE.
 
-Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. Among them, capacityCoefficient will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the capacityCoefficient value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
+Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. If a valid `backend_load_capacity_coeficient` parameter is configured (value range `0.0`~`1.0`), then `capacityCoefficient = backend_load_capacity_coeficient`. Otherwise, `capacityCoefficient` will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the `capacityCoefficient` value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
 
 `capacityCoefficient = 2 * Disk Utilization - 0.5`
 

i18n/zh-CN/docusaurus-plugin-content-docs/current/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -210,7 +210,7 @@ Doris 会自动进行集群内的副本均衡。目前支持两种均衡策略
 
 我们用 ClusterLoadStatistics（CLS）表示一个 cluster 中各个 Backend 的负载均衡情况。TabletScheduler 根据这个统计值，来触发集群均衡。我们当前通过 **磁盘使用率** 和 **副本数量** 两个指标，为每个 BE 计算一个 loadScore，作为 BE 的负载分数。分数越高，表示该 BE 的负载越重。
 
-磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。其中 capacityCoefficient 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 capacityCoefficient 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
+磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。如果系统配置了有效的 `backend_load_capacity_coeficient` 参数（取值范围 `0.0`~`1.0`），则 `capacityCoefficient = backend_load_capacity_coeficient`。否则，`capacityCoefficient` 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 `capacityCoefficient` 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
 
 `capacityCoefficient= 2 * 磁盘使用率 - 0.5`
 
@@ -762,4 +762,3 @@ TabletScheduler 在每轮调度时，都会通过 LoadBalancer 来选择一定
 5. 按需关闭 colocation 表的调度任务，集中集群资源修复其他高优数据。
 
 
-

i18n/zh-CN/docusaurus-plugin-content-docs/version-2.1/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -210,7 +210,7 @@ Doris 会自动进行集群内的副本均衡。目前支持两种均衡策略
 
 我们用 ClusterLoadStatistics（CLS）表示一个 cluster 中各个 Backend 的负载均衡情况。TabletScheduler 根据这个统计值，来触发集群均衡。我们当前通过 **磁盘使用率** 和 **副本数量** 两个指标，为每个 BE 计算一个 loadScore，作为 BE 的负载分数。分数越高，表示该 BE 的负载越重。
 
-磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。其中 capacityCoefficient 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 capacityCoefficient 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
+磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。如果系统配置了有效的 `backend_load_capacity_coeficient` 参数（取值范围 `0.0`~`1.0`），则 `capacityCoefficient = backend_load_capacity_coeficient`。否则，`capacityCoefficient` 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 `capacityCoefficient` 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
 
 `capacityCoefficient= 2 * 磁盘使用率 - 0.5`
 
@@ -762,4 +762,3 @@ TabletScheduler 在每轮调度时，都会通过 LoadBalancer 来选择一定
 5. 按需关闭 colocation 表的调度任务，集中集群资源修复其他高优数据。
 
 
-

i18n/zh-CN/docusaurus-plugin-content-docs/version-3.x/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -210,7 +210,7 @@ Doris 会自动进行集群内的副本均衡。目前支持两种均衡策略
 
 我们用 ClusterLoadStatistics（CLS）表示一个 cluster 中各个 Backend 的负载均衡情况。TabletScheduler 根据这个统计值，来触发集群均衡。我们当前通过 **磁盘使用率** 和 **副本数量** 两个指标，为每个 BE 计算一个 loadScore，作为 BE 的负载分数。分数越高，表示该 BE 的负载越重。
 
-磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。其中 capacityCoefficient 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 capacityCoefficient 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
+磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。如果系统配置了有效的 `backend_load_capacity_coeficient` 参数（取值范围 `0.0`~`1.0`），则 `capacityCoefficient = backend_load_capacity_coeficient`。否则，`capacityCoefficient` 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 `capacityCoefficient` 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
 
 `capacityCoefficient= 2 * 磁盘使用率 - 0.5`
 

i18n/zh-CN/docusaurus-plugin-content-docs/version-4.x/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -210,7 +210,7 @@ Doris 会自动进行集群内的副本均衡。目前支持两种均衡策略
 
 我们用 ClusterLoadStatistics（CLS）表示一个 cluster 中各个 Backend 的负载均衡情况。TabletScheduler 根据这个统计值，来触发集群均衡。我们当前通过 **磁盘使用率** 和 **副本数量** 两个指标，为每个 BE 计算一个 loadScore，作为 BE 的负载分数。分数越高，表示该 BE 的负载越重。
 
-磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。其中 capacityCoefficient 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 capacityCoefficient 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
+磁盘使用率和副本数量各有一个权重系数，分别为 **capacityCoefficient** 和 **replicaNumCoefficient**，其 **和恒为 1**。如果系统配置了有效的 `backend_load_capacity_coeficient` 参数（取值范围 `0.0`~`1.0`），则 `capacityCoefficient = backend_load_capacity_coeficient`。否则，`capacityCoefficient` 会根据实际磁盘使用率动态调整。当一个 BE 的总体磁盘使用率在 50% 以下，则 `capacityCoefficient` 值为 0.5，如果磁盘使用率在 75%（可通过 FE 配置项 `capacity_used_percent_high_water` 配置）以上，则值为 1。如果使用率介于 50% ~ 75% 之间，则该权重系数平滑增加，公式为：
 
 `capacityCoefficient= 2 * 磁盘使用率 - 0.5`
 
@@ -762,4 +762,3 @@ TabletScheduler 在每轮调度时，都会通过 LoadBalancer 来选择一定
 5. 按需关闭 colocation 表的调度任务，集中集群资源修复其他高优数据。
 
 
-

versioned_docs/version-2.1/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -206,7 +206,7 @@ Similarly, replica balancing ensures that a copy of the same table will not be d
 
 We use Cluster LoadStatistics (CLS) to represent the load balancing of each backend in a cluster. Tablet Scheduler triggers cluster equilibrium based on this statistic. We currently calculate a load Score for each BE as the BE load score by using **disk usage** and **number of copies**. The higher the score, the heavier the load on the BE.
 
-Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. Among them, capacityCoefficient will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the capacityCoefficient value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
+Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. If a valid `backend_load_capacity_coeficient` parameter is configured (value range `0.0`~`1.0`), then `capacityCoefficient = backend_load_capacity_coeficient`. Otherwise, `capacityCoefficient` will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the `capacityCoefficient` value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
 
 `capacityCoefficient = 2 * Disk Utilization - 0.5`
 

versioned_docs/version-3.x/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -206,7 +206,7 @@ Similarly, replica balancing ensures that a copy of the same table will not be d
 
 We use Cluster LoadStatistics (CLS) to represent the load balancing of each backend in a cluster. Tablet Scheduler triggers cluster equilibrium based on this statistic. We currently calculate a load Score for each BE as the BE load score by using **disk usage** and **number of copies**. The higher the score, the heavier the load on the BE.
 
-Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. Among them, capacityCoefficient will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the capacityCoefficient value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
+Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. If a valid `backend_load_capacity_coeficient` parameter is configured (value range `0.0`~`1.0`), then `capacityCoefficient = backend_load_capacity_coeficient`. Otherwise, `capacityCoefficient` will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the `capacityCoefficient` value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
 
 `capacityCoefficient = 2 * Disk Utilization - 0.5`
 

versioned_docs/version-4.x/admin-manual/maint-monitor/tablet-repair-and-balance.md

@@ -206,7 +206,7 @@ Similarly, replica balancing ensures that a copy of the same table will not be d
 
 We use Cluster LoadStatistics (CLS) to represent the load balancing of each backend in a cluster. Tablet Scheduler triggers cluster equilibrium based on this statistic. We currently calculate a load Score for each BE as the BE load score by using **disk usage** and **number of copies**. The higher the score, the heavier the load on the BE.
 
-Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. Among them, capacityCoefficient will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the capacityCoefficient value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
+Disk usage and number of copies have a weight factor, which is **capacityCoefficient** and **replicaNumCoefficient**, respectively. The sum of them is **constant to 1**. If a valid `backend_load_capacity_coeficient` parameter is configured (value range `0.0`~`1.0`), then `capacityCoefficient = backend_load_capacity_coeficient`. Otherwise, `capacityCoefficient` will dynamically adjust according to actual disk utilization. When the overall disk utilization of a BE is below 50%, the `capacityCoefficient` value is 0.5, and if the disk utilization is above 75% (configurable through the FE configuration item `capacity_used_percent_high_water`), the value is 1. If the utilization rate is between 50% and 75%, the weight coefficient increases smoothly. The formula is as follows:
 
 `capacityCoefficient = 2 * Disk Utilization - 0.5`