*: refine alert-rules.md and the titles of several migration docs (pi…

…ngcap#5001)

* *: refine alert-rules.md and the titles of several migration docs

* Update alert-rules.md

TOC.md

@@ -40,7 +40,7 @@
   + [Overview](/migration-overview.md)
   + Migrate from MySQL
     + [Migrate from Amazon Aurora MySQL Using TiDB Lightning](/migrate-from-aurora-using-lightning.md)
-    + [Migrate Using Dumpling and TiDB Lightning](/migrate-from-mysql-dumpling-files.md)
+    + [Migrate from MySQL SQL Files Using TiDB Lightning](/migrate-from-mysql-dumpling-files.md)
     + [Migrate from Amazon Aurora MySQL Using DM](/migrate-from-aurora-mysql-database.md)
   + Migrate from CSV Files
     + [Use TiDB Lightning](/tidb-lightning/migrate-from-csv-using-tidb-lightning.md)

alert-rules.md

@@ -10,16 +10,20 @@ aliases: ['/docs/dev/alert-rules/','/docs/dev/reference/alert-rules/']
 
 This document describes the alert rules for different components in a TiDB cluster, including the rule descriptions and solutions of the alert items in TiDB, TiKV, PD, TiDB Binlog, Node_exporter and Blackbox_exporter.
 
-According to the severity level, alert rules are divided into three categories (from high to low): emergency-level, critical-level and warning-level.
+According to the severity level, alert rules are divided into three categories (from high to low): emergency-level, critical-level, and warning-level. This division of severity levels applies to all alert items of each component below.
+
+|  Severity level |  Description   |
+| :-------- | :----- |
+|  Emergency-level  |  The highest severity level at which the service is unavailable. Emergency-level alerts are often caused by a service or node failure. **Manual intervention is required immediately**. |
+|  Critical-level  |  Decreased service availability. For the critical-level alerts, a close watch on the abnormal metrics is required. |
+|  Warning-level  |  Warning-level alerts are a reminder for an issue or error.   |
 
 ## TiDB alert rules
 
 This section gives the alert rules for the TiDB component.
 
 ### Emergency-level alerts
 
-Emergency-level alerts are often caused by a service or node failure. Manual intervention is required immediately.
-
 #### `TiDB_schema_error`
 
 * Alert rule:
@@ -79,8 +83,6 @@ Emergency-level alerts are often caused by a service or node failure. Manual int
 
 ### Critical-level alerts
 
-For the critical-level alerts, a close watch on the abnormal metrics is required.
-
 #### `TiDB_server_panic_total`
 
 * Alert rule:
@@ -97,8 +99,6 @@ For the critical-level alerts, a close watch on the abnormal metrics is required
 
 ### Warning-level alerts
 
-Warning-level alerts are a reminder for an issue or error.
-
 #### `TiDB_memory_abnormal`
 
 * Alert rule:
@@ -193,8 +193,6 @@ This section gives the alert rules for the PD component.
 
 ### Emergency-level alerts
 
-Emergency-level alerts are often caused by a service or node failure. Manual intervention is required immediately.
-
 #### `PD_cluster_offline_tikv_nums`
 
 * Alert rule:
@@ -212,8 +210,6 @@ Emergency-level alerts are often caused by a service or node failure. Manual int
 
 ### Critical-level alerts
 
-For the critical-level alerts, a close watch on the abnormal metrics is required.
-
 #### `PD_etcd_write_disk_latency`
 
 * Alert rule:
@@ -247,8 +243,6 @@ For the critical-level alerts, a close watch on the abnormal metrics is required
 
 ### Warning-level alerts
 
-Warning-level alerts are a reminder for an issue or error.
-
 #### `PD_cluster_lost_connect_tikv_nums`
 
 * Alert rule:
@@ -413,8 +407,6 @@ This section gives the alert rules for the TiKV component.
 
 ### Emergency-level alerts
 
-Emergency-level alerts are often caused by a service or node failure. Manual intervention is required immediately.
-
 #### `TiKV_memory_used_too_fast`
 
 * Alert rule:
@@ -451,8 +443,6 @@ Emergency-level alerts are often caused by a service or node failure. Manual int
 
 ### Critical-level alerts
 
-For the critical-level alerts, a close watch on the abnormal metrics is required.
-
 #### `TiKV_server_report_failure_msg_total`
 
 * Alert rule:
@@ -637,8 +627,6 @@ For the critical-level alerts, a close watch on the abnormal metrics is required
 
 ### Warning-level alerts
 
-Warning-level alerts are a reminder for an issue or error.
-
 #### `TiKV_leader_drops`
 
 * Alert rule:
@@ -817,8 +805,6 @@ This section gives the alert rules for the Node_exporter host.
 
 ### Emergency-level alerts
 
-Emergency-level alerts are often caused by a service or node failure. Manual intervention is required immediately.
-
 #### `NODE_disk_used_more_than_80%`
 
 * Alert rule:
@@ -866,8 +852,6 @@ Emergency-level alerts are often caused by a service or node failure. Manual int
 
 ### Critical-level alerts
 
-For the critical-level alerts, a close watch on the abnormal metrics is required.
-
 #### `NODE_memory_used_more_than_80%`
 
 * Alert rule:
@@ -885,8 +869,6 @@ For the critical-level alerts, a close watch on the abnormal metrics is required
 
 ### Warning-level alerts
 
-Warning-level alerts are a reminder for an issue or error.
-
 #### `NODE_node_overload`
 
 * Alert rule:
@@ -970,8 +952,6 @@ This section gives the alert rules for the Blackbox_exporter TCP, ICMP, and HTTP
 
 ### Emergency-level alerts
 
-Emergency-level alerts are often caused by a service or node failure. Manual intervention is required immediately.
-
 #### `TiDB_server_is_down`
 
 * Alert rule:
@@ -1150,8 +1130,6 @@ Emergency-level alerts are often caused by a service or node failure. Manual int
 
 ### Warning-level alerts
 
-Warning-level alerts are a reminder for an issue or error.
-
 #### `BLACKER_ping_latency_more_than_1s`
 
 * Alert rule:

migrate-from-aurora-mysql-database.md

@@ -1,9 +1,9 @@
 ---
-title: Migrate from MySQL (Amazon Aurora)
+title: Migrate from Amazon Aurora MySQL Using DM
 summary: Learn how to migrate from MySQL (using a case of Amazon Aurora) to TiDB by using TiDB Data Migration (DM).
 aliases: ['/docs/dev/migrate-from-aurora-mysql-database/','/docs/dev/how-to/migrate/from-mysql-aurora/','/docs/dev/how-to/migrate/from-aurora/']
 ---
 
-# Migrate from MySQL (Amazon Aurora)
+# Migrate from Amazon Aurora MySQL Using DM
 
 To migrate data from MySQL (Amazon Aurora) to TiDB, refer to [Migrate from MySQL (Amazon Aurora)](https://docs.pingcap.com/tidb-data-migration/v2.0/migrate-from-mysql-aurora).

migrate-from-mysql-dumpling-files.md

@@ -1,10 +1,10 @@
 ---
-title: Migrate Data from MySQL SQL Files
+title: Migrate from MySQL SQL Files Using TiDB Lightning
 summary: Learn how to migrate data from MySQL SQL files to TiDB using TiDB Lightning.
 aliases: ['/docs/dev/migrate-from-mysql-mydumper-files/','/tidb/dev/migrate-from-mysql-mydumper-files/']
 ---
 
-# Migrate Data from MySQL SQL Files
+# Migrate from MySQL SQL Files Using TiDB Lightning
 
 This document describes how to migrate data from MySQL SQL files to TiDB using TiDB Lightning. For details on how to generate MySQL SQL files, refer to [Dumpling](/dumpling-overview.md).
 

tidb-lightning/tidb-lightning-faq.md

@@ -188,7 +188,7 @@ See also [How to properly restart TiDB Lightning?](#how-to-properly-restart-tidb
 
 ## Why does TiDB Lightning report the `could not find first pair, this shouldn't happen` error?
 
-This error occurs possibly because the number of files opened by TiDB Lightning exceeds the system limit when TiDB Lightning reads the sorted local files. In the Linux system, you can use the `ulimit -n` command to confirm whether the value of this system limit is too small. It is recommended that you adjust this value to `1000000` (`ulimit -n 1000000`) during Lightning import.
+This error occurs possibly because the number of files opened by TiDB Lightning exceeds the system limit when TiDB Lightning reads the sorted local files. In the Linux system, you can use the `ulimit -n` command to confirm whether the value of this system limit is too small. It is recommended that you adjust this value to `1000000` (`ulimit -n 1000000`) during TiDB Lightning import.
 
 ## Import speed is too slow