en: update doc for tiflash on eks and ack (#276)

* en: update tiflash on ack * en: update ack and eks * update tiflash scaling in * Apply suggestions from code review Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com> * Apply suggestions from code review Co-authored-by: DanielZhangQD <36026334+DanielZhangQD@users.noreply.github.com> Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com> * Update en/scale-a-tidb-cluster.md Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com> * update wording Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com> Co-authored-by: DanielZhangQD <36026334+DanielZhangQD@users.noreply.github.com>
pingcap · May 28, 2020 · 3cba71c · 3cba71c
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diff --git a/en/deploy-on-alibaba-cloud.md b/en/deploy-on-alibaba-cloud.md
@@ -90,6 +90,8 @@ All the instances except ACK mandatory workers are deployed across availability
     operator_version = "v1.1.0-rc.1"
     ```
 
+    If you need to deploy TiFlash in the cluster, set `create_tiflash_node_pool = true` in `terraform.tfvars`. You can also configure the node count and instance type of the TiFlash node pool by modifying `tiflash_count` and `tiflash_instance_type`. By default, the value of `tiflash_count` is `2`, and the value of `tiflash_instance_type` is `ecs.i2.2xlarge`.
+
     > **Note:**
     >
     > Check the `operator_version` in the `variables.tf` file for the default TiDB Operator version of the current scripts. If the default version is not your desired one, configure `operator_version` in `terraform.tfvars`.
@@ -167,10 +169,35 @@ All the instances except ACK mandatory workers are deployed across availability
 
     To complete the CR file configuration, refer to [TiDB Operator API documentation](api-references.md) and [Configuring TiDB Cluster](configure-cluster-using-tidbcluster.md).
 
+    If you need to deploy TiFlash, configure `spec.tiflash` in `db.yaml` as follows:
+
+    ```yaml
+    spec
+      ...
+      tiflash:
+        baseImage: pingcap/tiflash
+        maxFailoverCount: 3
+        nodeSelector:
+          dedicated: TIDB_CLUSTER_NAME-tiflash
+        replicas: 1
+        storageClaims:
+        - resources:
+            requests:
+              storage: 100Gi
+          storageClassName: local-volume
+        tolerations:
+        - effect: NoSchedule
+          key: dedicated
+          operator: Equal
+          value: TIDB_CLUSTER_NAME-tiflash
+    ```
+
+    Modify `replicas`, `storageClaims[].resources.requests.storage`, and `storageClassName` according to your needs.
+
     > **Note:**
     >
     > * Replace all the `TIDB_CLUSTER_NAME` in the `db.yaml` and `db-monitor.yaml` files with `tidb_cluster_name` configured in the deployment of ACK.
-    > * Make sure the number of PD, TiKV, and TiDB nodes is the same as the `replicas` value of the corresponding component in `db.yaml`.
+    > * Make sure the number of PD, TiKV, TiFlash, or TiDB nodes is >= the `replicas` value of the corresponding component in `db.yaml`.
     > * Make sure `spec.initializer.version` in `db-monitor.yaml` is the same as `spec.version` in `db.yaml`. Otherwise, the monitor might not display correctly.
 
 2. Create `Namespace`:
@@ -237,12 +264,17 @@ This may take a while to complete. You can watch the process using the following
 kubectl get pods --namespace ${namespace} -o wide --watch
 ```
 
-## Scale
+## Scale out TiDB cluster
 
-To scale the TiDB cluster, modify `tikv_count` or `tidb_count` in the `terraform.tfvars` file, and then run `terraform apply` to scale out the number of nodes for the corresponding components.
+To scale out the TiDB cluster, modify `tikv_count`, `tiflash_count` or `tidb_count` in the `terraform.tfvars` file, and then run `terraform apply` to scale out the number of nodes for the corresponding components.
 
 After the nodes scale out, modify the `replicas` of the corresponding components by running `kubectl --kubeconfig credentials/kubeconfig edit tc ${tidb_cluster_name} -n ${namespace}`.
 
+> **Note:**
+>
+> - Because it is impossible to determine which node will be taken offline during the scale-in process, the scale-in of TiDB clusters is currently not supported.
+> - The scale-out process takes a few minutes. You can watch the status by running `kubectl --kubeconfig credentials/kubeconfig get po -n ${namespace} --watch`.
+
 ## Configure
 
 ### Configure TiDB Operator
@@ -317,6 +349,8 @@ All the configurable parameters in `tidb-cluster` are as follows:
 | `pd_instance_type` | The PD instance type | `ecs.g5.large` |
 | `tikv_count` | The number of TiKV nodes | 3 |
 | `tikv_instance_type` | The TiKV instance type | `ecs.i2.2xlarge` |
+| `tiflash_count` | The count of TiFlash nodes | 2 |
+| `tiflash_instance_type` | The TiFlash instance type | `ecs.i2.2xlarge` |
 | `tidb_count` | The number of TiDB nodes | 2 |
 | `tidb_instance_type` | The TiDB instance type | `ecs.c5.4xlarge` |
 | `monitor_instance_type` | The instance type of monitoring components | `ecs.c5.xlarge` |

diff --git a/en/deploy-on-aws-eks.md b/en/deploy-on-aws-eks.md
@@ -72,9 +72,9 @@ Before deploying a TiDB cluster on AWS EKS, make sure the following requirements
 
 This section describes how to deploy EKS, TiDB operator, TiDB cluster and monitor.
 
-### Deploy EKS and TiDB Operator
+### Deploy EKS, TiDB Operator, and TiDB cluster node pool
 
-Use the following commands to deploy EKS and TiDB Operator.
+Use the following commands to deploy EKS, TiDB Operator, and the TiDB cluster node pool.
 
 Get the code from Github:
 
@@ -105,6 +105,8 @@ eks_name = "my-cluster"
 operator_version = "v1.1.0-rc.1"
 ```
 
+If you need to deploy TiFlash in the cluster, set `create_tiflash_node_pool = true` in `terraform.tfvars`. You can also configure the node count and instance type of the TiFlash node pool by modifying `cluster_tiflash_count` and `cluster_tiflash_instance_type`. By default, the value of `cluster_tiflash_count` is `2`, and the value of `cluster_tiflash_instance_type` is `i3.4xlarge`.
+
 > **Note:**
 >
 > Check the `operator_version` in the `variables.tf` file for the default TiDB Operator version of the current scripts. If the default version is not your desired one, configure `operator_version` in `terraform.tfvars`.
@@ -159,12 +161,37 @@ You can use the `terraform output` command to get the output again.
     cp manifests/db.yaml.example db.yaml && cp manifests/db-monitor.yaml.example db-monitor.yaml
     ```
 
-    To complete the CR file configuration, refer to [API documentation](api-references.md).
+    To complete the CR file configuration, refer to [API documentation](api-references.md) and [Configure a TiDB Cluster Using TidbCluster](configure-cluster-using-tidbcluster.md).
+
+    To deploy TiFlash, configure `spec.tiflash` in `db.yaml` as follows:
+
+    ```yaml
+    spec:
+      ...
+      tiflash:
+        baseImage: pingcap/tiflash
+        maxFailoverCount: 3
+        nodeSelector:
+          dedicated: CLUSTER_NAME-tiflash
+        replicas: 1
+        storageClaims:
+        - resources:
+            requests:
+              storage: 100Gi
+          storageClassName: local-storage
+        tolerations:
+        - effect: NoSchedule
+          key: dedicated
+          operator: Equal
+          value: CLUSTER_NAME-tiflash
+    ```
+
+    Modify `replicas`, `storageClaims[].resources.requests.storage`, and `storageClassName` according to your needs.
 
     > **Note:**
     >
     > * Replace all `CLUSTER_NAME` in `db.yaml` and `db-monitor.yaml` files with `default_cluster_name` configured during EKS deployment.
-    > * Make sure that during EKS deployment, the number of PD, TiKV or TiDB nodes is consistent with the value of the `replicas` field of the corresponding component in `db.yaml`.
+    > * Make sure that during EKS deployment, the number of PD, TiKV, TiFlash, or TiDB nodes is >= the value of the `replicas` field of the corresponding component in `db.yaml`.
     > * Make sure that `spec.initializer.version` in `db-monitor.yaml` and `spec.version` in `db.yaml` are the same to ensure normal monitor display.
 
 2. Create `Namespace`:
@@ -263,7 +290,7 @@ The upgrading doesn't finish immediately. You can watch the upgrading progress b
 
 ## Scale
 
-To scale the TiDB cluster, modify the `default_cluster_tikv_count` or `default_cluster_tidb_count` variable in the `terraform.tfvars` file to your desired count, and then run `terraform apply` to scale out the number of the corresponding component nodes.
+To scale out the TiDB cluster, modify the `default_cluster_tikv_count`, `cluster_tiflash_count`, or `default_cluster_tidb_count` variable in the `terraform.tfvars` file to your desired count, and then run `terraform apply` to scale out the number of the corresponding component nodes.
 
 After the scaling, modify the `replicas` of the corresponding component by the following command:
 

diff --git a/en/scale-a-tidb-cluster.md b/en/scale-a-tidb-cluster.md
@@ -16,9 +16,61 @@ Currently, the TiDB cluster supports management by Helm or by TidbCluster Custom
 
 ### Horizontal scaling operations (CR)
 
+#### Scale PD, TiDB, and TiKV
+
 Modify `spec.pd.replicas`, `spec.tidb.replicas`, and `spec.tikv.replicas` in the `TidbCluster` object of the cluster to a desired value using kubectl.
 
-If TiFlash is deployed in the cluster, you can scale in and out TiFlash by modifying `spec.tiflash.replicas`.
+#### Scale out TiFlash
+
+If TiFlash is deployed in the cluster, you can scale out TiFlash by modifying `spec.tiflash.replicas`.
+
+#### Scale in TiFlash
+
+1. Expose the PD service by using `port-forward`:
+
+    {{< copyable "shell-regular" >}}
+
+    ```shell
+    kubectl port-forward -n ${namespace} svc/${cluster_name}-pd 2379:2379
+    ```
+
+2. Open a **new** terminal tab or window. Check the maximum number (`N`) of replicas of all data tables with which TiFlash is enabled by running the following command:
+
+    {{< copyable "shell-regular" >}}
+
+    ```shell
+    curl 127.0.0.1:2379/pd/api/v1/config/rules/group/tiflash | grep count
+    ```
+
+    In the printed result, the largest value of `count` is the maximum number (`N`) of replicas of all data tables.
+
+3. Go back to the terminal window in Step 1, where `port-forward` is running. Press <kbd>Ctrl</kbd>+<kbd>C</kbd> to stop `port-forward`.
+
+4. After the scale-in operation, if the number of remaining Pods in TiFlash >= `N`, skip to Step 6. Otherwise, take the following steps:
+
+    1. Refer to [Access TiDB](access-tidb.md) and connect to the TiDB service.
+
+    2. For all the tables that have more replicas than the remaining Pods in TiFlash, run the following command:
+
+        {{< copyable "sql" >}}
+
+        ```sql
+        alter table <db-name>.<table-name> set tiflash replica 0;
+        ```
+
+5. Wait for TiFlash replicas in the related tables to be deleted.
+
+    Connect to the TiDB service, and run the following command:
+
+    {{< copyable "sql" >}}
+
+    ```sql
+    SELECT * FROM information_schema.tiflash_replica WHERE TABLE_SCHEMA = '<db_name>' and TABLE_NAME = '<table_name>';
+    ```
+
+    If you cannot view the replication information of related tables, the TiFlash replicas are successfully deleted.
+
+6. Modify `spec.tiflash.replicas` to scale in TiFlash.
 
 ### Horizontal scaling operations (Helm)