tiflash: add tiflash configuration document (#2188)

TOC.md

@@ -300,6 +300,7 @@
     - [Deploy a TiFlash Cluster](/reference/tiflash/deploy.md)
     - [Use TiFlash](/reference/tiflash/use-tiflash.md)
     - [Monitor TiFlash](/reference/tiflash/monitor.md)
+    - [Configure TiFlash](/reference/tiflash/configuration.md)
   + TiDB Binlog
     - [Overview](/reference/tidb-binlog/overview.md)
     - [Deploy](/reference/tidb-binlog/deploy.md)

reference/configuration/pd-server/configuration-file.md

@@ -238,6 +238,11 @@ Configuration items related to scheduling
 + Determines whether to disable isolation level check. When this parameter is set to `true`, PD does not increase the isolation level of the Region replicas through scheduling.
 + Default value: `false`
 
+### `store-balance-rate`
+
++ Determines the maximum number of operations related to adding peers within a minute
++ Default value: `15`
+
 ## `replication`
 
 Configuration items related to replicas

reference/tiflash/configuration.md

@@ -0,0 +1,80 @@
+---
+title: Configure TiFlash
+summary: Learn how to configure TiFlash.
+category: reference
+---
+
+# Configure TiFlash
+
+This document introduces the configuration parameters related to the deployment and use of TiFlash.
+
+## PD scheduling parameters
+
+You can adjust the PD scheduling parameters using [pd-ctl](/reference/tools/pd-control.md) (the binary file in `resources/bin` in the tidb-ansible directory):
+
+- [`replica-schedule-limit`](/reference/configuration/pd-server/configuration-file.md#replica-schedule-limit): determines the rate at which the replica-related operator is generated. The parameter affects operations such as making nodes offline and add replicas.
+
+    > **Notes:**
+    >
+    > The value of this parameter should be less than that of `region-schedule-limit`. Otherwise, the normal Region scheduling among TiKV nodes is affected.
+
+- [`store-balance-rate`](/reference/configuration/pd-server/configuration-file.md#store-balance-rate): limits the rate at which each store is scheduled.
+
+## TiFlash configuration parameters
+
+This section introduces the configuration parameters of TiFlash.
+
+### Configure the `tiflash.toml` file
+
+```
+tmp_path = The path in which the TiFlash temporary files are stored.
+path = The TiFlash data storage path.     # If there are multiple directories, separate each directory with a comma. For example, `/ssd_a/data/tiflash,/hdd_b/data/tiflash,/hdd_c/data/tiflash`. If your environment has multiple disks, it is recommended that each path corresponds to one disk and you put disks with best performance at the front to fully use performance of all disks.
+path_realtime_mode = false # The default value is `false`. If you set it to `true` and multiple directories are deployed in the path, the latest data is stored in the first directory and older data is stored in the rest directories.
+listen_host = The TiFlash service listening host. # Generally, it is configured as `0.0.0.0`.
+tcp_port = The TiFlash TCP service port.
+http_port = The TiFlash HTTP service port.
+```
+
+```
+[flash]
+    tidb_status_addr = TiDB status port and address. # Multiple addresses are separated with commas.
+    service_addr = The listening address of TiFlash Raft services and coprocessor services.
+```
+
+Multiple TiFlash nodes elect a master to add or delete placement rules to PD, and you need three parameters to control this process.
+
+```
+[flash.flash_cluster]
+    refresh_interval = Master regularly refreshes the valid period.
+    update_rule_interval = Master regularly gets the status of TiFlash replicas and interacts with PD.
+    master_ttl = The valid period of the elected master.
+    cluster_manager_path = The absolute path of the pd buddy directory.
+    log = The pd buddy log path.
+
+[flash.proxy]
+    addr = The listening address of proxy.
+    advertise-addr = The external access address of proxy.
+    data-dir = The data storage path of proxy.
+    config = The proxy configuration file path.
+    log-file = The proxy log path.
+
+[logger]
+    level = log level (available options: trace, debug, information, warning, error).
+    log = The TiFlash log path.
+    errorlog = The TiFlash error log path.
+    size = The size of a single log file.
+    count = The maximum number of log files to save.
+[raft]
+    kvstore_path = The storage path of the kvstore data. # The default setting: "{the first directory of the path}/kvstore"
+    pd_addr = PD service address. # Multiple addresses are separated with commas.
+[status]
+    metrics_port = The port through which Prometheus pulls metrics information.
+```
+
+### Configure the `tiflash-learner.toml` file
+
+```
+[server]
+    engine-addr = The listening address of the TiFlash Raft service.
+    status-addr = The port and IP through which Prometheus pulls proxy metrics information.
+```