1.问题
使用mycat配置主从读写分离，启动mycat报错信息如下：
STATUS | wrapper | 2020/06/17 17:00:11 | --> Wrapper Started as Daemon STATUS | wrapper | 2020/06/17 17:00:11 | Launching a JVM... ERROR | wrapper | 2020/06/17 17:00:11 | JVM exited while loading the application. INFO | jvm 1 | 2020/06/17 17:00:11 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: mysql01: mysql01: Name or service not known STATUS | wrapper | 2020/06/17 17:00:15 | Launching a JVM... INFO | jvm 2 | 2020/06/17 17:00:16 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: mysql01: mysql01: Name or service not known ERROR | wrapper | 2020/06/17 17:00:16 | JVM exited while loading the application. STATUS | wrapper | 2020/06/17 17:00:20 | Launching a JVM... ERROR | wrapper | 2020/06/17 17:00:20 | JVM exited while loading the application. INFO | jvm 3 | 2020/06/17 17:00:20 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: mysql01: mysql01: Name or service not known STATUS | wrapper | 2020/06/17 17:00:25 | Launching a JVM... ERROR | wrapper | 2020/06/17 17:00:25 | JVM exited while loading the application. INFO | jvm 4 | 2020/06/17 17:00:25 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: mysql01: mysql01: Name or service not known STATUS | wrapper | 2020/06/17 17:00:29 | Launching a JVM... ERROR | wrapper | 2020/06/17 17:00:30 | JVM exited while loading the application. INFO | jvm 5 | 2020/06/17 17:00:30 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: mysql01: mysql01: Name or service not known FATAL | wrapper | 2020/06/17 17:00:30 | There were 5 failed launches in a row, each lasting less than 300 seconds. Giving up. FATAL | wrapper | 2020/06/17 17:00:30 | There may be a configuration problem: please check the logs. STATUS | wrapper | 2020/06/17 17:00:30 | <-- Wrapper Stopped
2.问题解决
原因：无法解析主机名
解决方法：
修改hosts文件
[mysql@mysql01 ~]$ cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 192.168.12.60 mysql01
再次启动mycat，状态正常。
[mysql@mysql01 ~]$ mycat status Mycat-server is running (37136).