MySQL5.7MHA+MaxScale2.0构建高可用环境
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mysql读写分离与负载均衡--MHA与MaxScale
环境介绍
Part1:写在最前
看了某大牛的文章，讲述了一下MaxScale比LVS的好处多多，那您倒是放出来配置文件啊~~大牛说：
需要的单独找我吧，太长了配置文件……
看到这我心中久久不能平静啊。。。联系不上您呐 = =，于是各种资料各种找啊~各种坑各种血崩啊！~~~
由于不知道大牛的配置文件是什么样子，本文仅以随笔的形式，记录下实施过程。也欢迎您和我探讨您在实施MaxScale时遇到的各种问题和心得体会。
Part2:环境
MySQL5.7 MHA + MaxScale2.0
192.168.1.248 HE1 slave1
192.168.1.249 HE2 slave2
192.168.1.250 HE3 master
192.168.1.251 HE4 MHA-manager
Part3:MHA
MHA的优点不作赘述，看下原理图吧
从宕机崩溃的Master保存二进制日志事件(binlogevent)
识别含有最新更新的Slave
应用差异的中继日志(relaylog)到其他Slave
应用从Master保存的二进制日志事件
提升一个Slave为新的Master
使其他的Slave连接新的Master进行复制
构建MySQL5.7MHA
Part1:写在最前
MHA的部署不是本文的叙述重点，网上比比皆是。这里只记录下MySQL5.7的MHA搭建时的一些坑
Part2:坑
①mha4mysql-manager-0.57.tar.gz
②mha4mysql-node-0.57.tar.gz
Warning:警告这两个包首先你要搞到，虽然说0.56什么的不代表支持的mysql版本，但经过测试，想要在MySQL5.7上部署MHA，少走坑，请用0.57的。
Part3:安装包的位置
请在所有的节点包括Manager节点安装好你的mha4mysql-node-0.57.tar.gz，以保证后期在管理节点执行perl Makefile.PL的时候，你能如愿以偿的看到如下信息
[[email protected] mha4mysql-manager-0.57]# perl Makefile.PL *** Module::AutoInstall version 1.06 *** Checking for Perl dependencies... [Core Features] - DBI ...loaded. (1.609) - DBD::mysql ...loaded. (4.013) - Time::HiRes ...loaded. (1.9721) - Config::Tiny ...loaded. (2.12) - Log::Dispatch ...loaded. (2.26) - Parallel::ForkManager ...loaded. (0.7.5) - MHA::NodeConst ...loaded. (0.57) *** Module::AutoInstall configuration finished. Writing Makefile for mha4mysql::manager
Part4:一些常见错误记录
如果遇到
①这样
[[email protected] bin]# masterha_check_repl --conf=/etc/mha/mha.conf Tue Apr 5 22:09:32 2016 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Tue Apr 5 22:09:32 2016 - [info] Reading application default configuration from /etc/mha/mha.conf.. Tue Apr 5 22:09:32 2016 - [info] Reading server configuration from /etc/mha/mha.conf.. Tue Apr 5 22:09:32 2016 - [info] MHA::MasterMonitor version 0.57. Tue Apr 5 22:09:32 2016 - [error][/usr/local/lib64/perl5/MHA/ServerManager.pm, ln188] There is no alive server. We can‘t do failover Tue Apr 5 22:09:32 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations. at /usr/local/lib64/perl5/MHA/MasterMonitor.pm line 326 Tue Apr 5 22:09:32 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln523] Error happened on monitoring servers. Tue Apr 5 22:09:32 2016 - [info] Got exit code 1 (Not master dead).
解决方案
用的不是默认端口3306，请修改你的配置文件
②这样
[[email protected] ~]# masterha_check_repl --conf=/etc/mha/mha.conf Tue Apr 5 22:36:33 2016 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Tue Apr 5 22:36:33 2016 - [info] Reading application default configuration from /etc/mha/mha.conf.. Tue Apr 5 22:36:33 2016 - [info] Reading server configuration from /etc/mha/mha.conf.. Tue Apr 5 22:36:33 2016 - [info] MHA::MasterMonitor version 0.57. Tue Apr 5 22:36:34 2016 - [info] GTID failover mode = 0 Tue Apr 5 22:36:34 2016 - [info] Dead Servers: Tue Apr 5 22:36:34 2016 - [info] Alive Servers: Tue Apr 5 22:36:34 2016 - [info] 192.168.1.250(192.168.1.250:4008) Tue Apr 5 22:36:34 2016 - [info] 192.168.1.248(192.168.1.248:4008) Tue Apr 5 22:36:34 2016 - [info] 192.168.1.249(192.168.1.249:4008) Tue Apr 5 22:36:34 2016 - [info] Alive Slaves: Tue Apr 5 22:36:34 2016 - [info] 192.168.1.248(192.168.1.248:4008) Version=5.6.16-log (oldest major version between slaves) log-bin:enabled Tue Apr 5 22:36:34 2016 - [info] Replicating from 192.168.1.250(192.168.1.250:4008) Tue Apr 5 22:36:34 2016 - [info] Primary candidate for the new Master (candidate_master is set) Tue Apr 5 22:36:34 2016 - [info] 192.168.1.249(192.168.1.249:4008) Version=5.6.16-log (oldest major version between slaves) log-bin:enabled Tue Apr 5 22:36:34 2016 - [info] Replicating from 192.168.1.250(192.168.1.250:4008) Tue Apr 5 22:36:34 2016 - [info] Not candidate for the new Master (no_master is set) Tue Apr 5 22:36:34 2016 - [info] Current Alive Master: 192.168.1.250(192.168.1.250:4008) Tue Apr 5 22:36:34 2016 - [info] Checking slave configurations.. Tue Apr 5 22:36:34 2016 - [warning] relay_log_purge=0 is not set on slave 192.168.1.248(192.168.1.248:4008). Tue Apr 5 22:36:34 2016 - [warning] relay_log_purge=0 is not set on slave 192.168.1.249(192.168.1.249:4008). Tue Apr 5 22:36:34 2016 - [info] Checking replication filtering settings.. Tue Apr 5 22:36:34 2016 - [info] binlog_do_db= , binlog_ignore_db= Tue Apr 5 22:36:34 2016 - [info] Replication filtering check ok. Tue Apr 5 22:36:34 2016 - [info] GTID (with auto-pos) is not supported Tue Apr 5 22:36:34 2016 - [info] Starting SSH connection tests.. Tue Apr 5 22:36:35 2016 - [info] All SSH connection tests passed successfully. Tue Apr 5 22:36:35 2016 - [info] Checking MHA Node version.. Tue Apr 5 22:36:36 2016 - [info] Version check ok. Tue Apr 5 22:36:36 2016 - [info] Checking SSH publickey authentication settings on the current master.. Tue Apr 5 22:36:36 2016 - [info] HealthCheck: SSH to 192.168.1.250 is reachable. Tue Apr 5 22:36:36 2016 - [info] Master MHA Node version is 0.57. Tue Apr 5 22:36:36 2016 - [info] Checking recovery script configurations on 192.168.1.250(192.168.1.250:4008).. Tue Apr 5 22:36:36 2016 - [info] Executing command: save_binary_logs --command=test --start_pos=4 --binlog_dir=/log/mysql --output_file=/usr/local/mha/save_binary_logs_test --manager_version=0.57 --start_file=mysql-bin.000009 Tue Apr 5 22:36:36 2016 - [info] Connecting to [email protected](192.168.1.250:22).. Creating /usr/local/mha if not exists.. Creating directory /usr/local/mha.. done. ok. Checking output directory is accessible or not.. ok. Binlog found at /log/mysql, up to mysql-bin.000009 Tue Apr 5 22:36:36 2016 - [info] Binlog setting check done. Tue Apr 5 22:36:36 2016 - [info] Checking SSH publickey authentication and checking recovery script configurations on all alive slave servers.. Tue Apr 5 22:36:36 2016 - [info] Executing command : apply_diff_relay_logs --command=test --slave_user=‘root‘ --slave_host=192.168.1.248 --slave_ip=192.168.1.248 --slave_port=4008 --workdir=/usr/local/mha --target_version=5.6.16-log --manager_version=0.57 --relay_log_info=/data/mysql/relay-log.info --relay_dir=/data/mysql/ --slave_pass=xxx Tue Apr 5 22:36:36 2016 - [info] Connecting to [email protected](192.168.1.248:22).. Can‘t exec "mysqlbinlog": No such file or directory at /usr/local/lib64/perl5/MHA/BinlogManager.pm line 106. mysqlbinlog version command failed with rc 1:0, please verify PATH, LD_LIBRARY_PATH, and client options at /usr/local/bin/apply_diff_relay_logs line 493 Tue Apr 5 22:36:36 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln205] Slaves settings check failed! Tue Apr 5 22:36:36 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln413] Slave configuration failed. Tue Apr 5 22:36:36 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations. at /usr/local/bin/masterha_check_repl line 48 Tue Apr 5 22:36:36 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln523] Error happened on monitoring servers. Tue Apr 5 22:36:36 2016 - [info] Got exit code 1 (Not master dead). MySQL Replication Health is NOT OK!
解决方案
[[email protected] MHA]# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/bin/mysqlbinlog
③或者这样
Binlog found at /log/mysql, up to mysql-bin.000009 Tue Apr 5 22:43:55 2016 - [info] Binlog setting check done. Tue Apr 5 22:43:55 2016 - [info] Checking SSH publickey authentication and checking recovery script configurations on all alive slave servers.. Tue Apr 5 22:43:55 2016 - [info] Executing command : apply_diff_relay_logs --command=test --slave_user=‘root‘ --slave_host=192.168.1.248 --slave_ip=192.168.1.248 --slave_port=4008 --workdir=/usr/local/mha --target_version=5.6.16-log --manager_version=0.57 --relay_log_info=/data/mysql/relay-log.info --relay_dir=/data/mysql/ --slave_pass=xxx Tue Apr 5 22:43:55 2016 - [info] Connecting to [email protected](192.168.1.248:22).. mysqlbinlog: unknown variable ‘default-character-set=utf8‘ mysqlbinlog version command failed with rc 7:0, please verify PATH, LD_LIBRARY_PATH, and client options at /usr/local/bin/apply_diff_relay_logs line 493 Tue Apr 5 22:43:55 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln205] Slaves settings check failed! Tue Apr 5 22:43:55 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln413] Slave configuration failed. Tue Apr 5 22:43:55 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations. at /usr/local/bin/masterha_check_repl line 48 Tue Apr 5 22:43:55 2016 - [error][/usr/local/lib64/perl5/MHA/MasterMonitor.pm, ln523] Error happened on monitoring servers. Tue Apr 5 22:43:55 2016 - [info] Got exit code 1 (Not master dead).
解决方案
注释掉my.cnf中的
[client]
#default-character-set=utf8
遇到上述错误别慌张，看日志，根据报错来排查问题。
折腾半天，就为了这个OK
[[email protected] mha4mysql-manager-0.57]# masterha_check_status --conf=/etc/mha/mha.conf
mha (pid:32726) is running(0:PING_OK), master:192.168.1.250
MaxScale2.0
Part1:写在最前
maxscale是mariadb公司开发的一套数据库中间件，可以很方便的实现读写分离方案；并且提供了读写分离的负载均衡和高可用性保障。另外maxscale对于前端应用而言是透明的，我们可以很方便的将应用迁移到maxscale中实现读写分离方案，来分担主库的压力。maxscale也提供了sql语句的解析过滤功能。这里我们主要讲解maxscale的安装、配置以及注意事项。
Part2:整体架构
Part3:安装
Maxscale配置很简单
[[email protected] MHA]# yum -y install maxscale-2.0.1-2.centos.6.x86_64.rpm (只在Maxscale上执行)
[[email protected] ~]# cat /etc/maxscale.cnf # MaxScale documentation on GitHub: # https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Documentation-Contents.md # Global parameters # # Number of threads is autodetected, uncomment for manual configuration # Complete list of configuration options: # https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Getting-Started/Configuration-Guide.md [maxscale] threads=auto # Server definitions # # Set the address of the server to the network # address of a MySQL server. # [server1] type=server address=192.168.1.248 port=3306 protocol=MySQLBackend myweight=5 [server2] type=server address=192.168.1.249 port=3306 protocol=MySQLBackend myweight=5 [server3] type=server address=192.168.1.100 port=3306 protocol=MySQLBackend # Monitor for the servers # # This will keep MaxScale aware of the state of the servers. # MySQL Monitor documentation: # https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Monitors/MySQL-Monitor.md [MySQL Monitor] type=monitor module=mysqlmon servers=server1,server2,server3 user=mysync passwd=MANAGER monitor_interval=10000 # Service definitions # # Service Definition for a read-only service and # a read/write splitting service. # # https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Routers/ReadConnRoute.md #[Read-Only Service] ###只读服务 #type=service #router=readconnroute #servers=server1,server2,server3 #user=sys_admin #passwd=MANAGER #router_options=slave # https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Routers/ReadWriteSplit.md [Read-Write Service] ####写服务 type=service router=readwritesplit enable_root_user=1 servers=server1,server2,server3 user=sys_admin passwd=MANAGER weightby=myweight router_options=slave_selection_criteria=LEAST_GLOBAL_CONNECTIONS max_slave_connections=1 # https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Reference/MaxAdmin.md [MaxAdmin Service] type=service router=cli #[Read-Only Listener] #type=listener #service=Read-Only Service #protocol=MySQLClient #port=4008 ##读服务启动监听 端口4008 [Read-Write Listener] type=listener service=Read-Write Service protocol=MySQLClient port=4006 ####写服务启动监听 端口 [MaxAdmin Listener] type=listener service=MaxAdmin Service protocol=maxscaled port=6603 ###管理端口
[[email protected] ~]# /etc/init.d/maxscale start
Starting MaxScale: maxscale (pid 28851) is running... [ OK ]
[[email protected] ~]# netstat -lntp |grep maxscale
tcp 0 0 0.0.0.0:6603 0.0.0.0:* LISTEN 29878/maxscale
tcp 0 0 0.0.0.0:4006 0.0.0.0:* LISTEN 29878/maxscale
[[email protected] ~]# maxadmin -pmariadb list services
Services.
--------------------------+----------------------+--------+---------------
Service Name | Router Module | #Users | Total Sessions
--------------------------+----------------------+--------+---------------
Read-Only Service | readconnroute | 1 | 5
Read-Write Service | readwritesplit | 1 | 11
MaxAdmin Service | cli | 2 | 3
--------------------------+----------------------+--------+---------------
[[email protected] ~]# maxadmin -pmariadb list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.1.248 | 3306 | 0 | Slave, Running
server2 | 192.168.1.249 | 3306 | 0 | Slave, Running
server3 | 192.168.1.250 | 3306 | 0 | Master, Running
-------------------+-----------------+-------+-------------+--------------------
至此，MHA+Maxscale的环境就完成了。
读写分离与负载均衡校验
Part1:读写分离
在Master构建相应的测试表
mysql> select * from helei; +--------+ | a | +--------+ | HE3 | +--------+ 3 rows in set (0.00 sec)
在slave1插入数据HE1
mysql> select * from helei; +------+ | a | +------+ | HE3 | | HE1 | +------+
在slave2插入数据HE2
mysql> select * from helei; +------+ | a | +------+ | HE3 | | HE2 | +------+
现在链接4006读写分离端口，进行数据写入
[[email protected] ~]# mysql -h192.168.1.250 -P 4006 -usys_admin -pMANAGER maxscale -e"insert into helei values(‘写入‘);" mysql: [Warning] Using a password on the command line interface can be insecure. [[email protected] ~]# mysql -h192.168.1.250 -P 4008 -usys_admin -pMANAGER maxscale -e"select * from helei;" mysql: [Warning] Using a password on the command line interface can be insecure. +--------+ | a | +--------+ | HE3 | | HE1 | | 写入 | +--------+
可以看到主库插入完毕后从库已经同步完成，这条查询完成在了HE1（slave1）上
Part2:负载均衡
我们配置的read比例为1:1
[[email protected] ~]# maxadmin -pmariadb show service "Read-Write Service" Service 0xef5570 Service: Read-Write Service Router: readwritesplit (0x7ff5e8fa6ec0) State: Started Number of router sessions: 15 Current no. of router sessions: 0 Number of queries forwarded: 41 Number of queries forwarded to master:2 (4.88%) Number of queries forwarded to slave: 39 (95.12%) Number of queries forwarded to all: 0 (0.00%) Connection distribution based on myweight server parameter. Server Target % Connections Operations Global Router server1 50.0% 0 0 0 server2 50.0% 0 0 0 server3 100.0% 0 0 0 Started: Thu Nov 3 23:46:27 2016 Root user access: Enabled Backend databases: 192.168.1.248:3306 Protocol: MySQLBackend 192.168.1.249:3306 Protocol: MySQLBackend 192.168.1.100:3306 Protocol: MySQLBackend Routing weight parameter: myweight Users data: 0xf09370 Total connections: 16 Currently connected: 1
[[email protected] ~]# for i in `seq 1 10`; do mysql -h 192.168.1.250 -P 4006 -usys_admin -pMANAGER maxscale -e "select @@hostname; select sleep(10)" 2>/dev/null & done [[email protected] ~]# +------------+ | @@hostname | +------------+ | HE1 | +------------+ +------------+ | @@hostname | +------------+ | HE1 | +------------+ +------------+ | @@hostname | +------------+ | HE1 | +------------+ +------------+ | @@hostname | +------------+ | HE1 | +------------+ +------------+ | @@hostname | +------------+ | HE1 | +------------+ +------------+ | @@hostname | +------------+ | HE2 | +------------+ +------------+ | @@hostname | +------------+ | HE2 | +------------+ +------------+ | @@hostname | +------------+ | HE2 | +------------+ +------------+ | @@hostname | +------------+ | HE2 | +------------+ +------------+ | @@hostname | +------------+ | HE2 | +------------+
OK!That‘s how it works!~
故障测试
Part1:stop slave故障
停止HE1的复制
[[email protected] ~]# mysql -uroot -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 74 Server version: 5.7.16-log MySQL Community Server (GPL) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement. mysql> stop slave; Query OK, 0 rows affected (0.05 sec) [[email protected] ~]# maxadmin -pmariadb list servers Servers. -------------------+-----------------+-------+-------------+-------------------- Server | Address | Port | Connections | Status -------------------+-----------------+-------+-------------+-------------------- server1 | 192.168.1.248 | 3306 | 0 | Running server2 | 192.168.1.249 | 3306 | 0 | Slave, Running server3 | 192.168.1.250 | 3306 | 0 | Master, Running -------------------+-----------------+-------+-------------+-------------------- [[email protected] ~]# mysql -h192.168.1.250 -P 4006 -usys_admin -pMANAGER maxscale -e"select * from helei;" mysql: [Warning] Using a password on the command line interface can be insecure. +--------+ | a | +--------+ | HE3 | | HE2 | | 写入 | +--------+ [[email protected] ~]# mysql -h192.168.1.250 -P 4006 -usys_admin -pMANAGER maxscale -e"select * from helei;" mysql: [Warning] Using a password on the command line interface can be insecure. +--------+ | a | +--------+ | HE3 | | HE2 | | 写入 | +--------+
可以看出，在slave1故障后，所有的读操作都进入了HE2(slave2)；
恢复HE1
mysql> start slave; Query OK, 0 rows affected (0.00 sec) [[email protected] ~]# maxadmin -pmariadb list servers Servers. -------------------+-----------------+-------+-------------+-------------------- Server | Address | Port | Connections | Status -------------------+-----------------+-------+-------------+-------------------- server1 | 192.168.1.248 | 3306 | 0 | Slave, Running server2 | 192.168.1.249 | 3306 | 0 | Slave, Running server3 | 192.168.1.250 | 3306 | 0 | Master, Running -------------------+-----------------+-------+-------------+-------------------- 验证 [[email protected] ~]# mysql -h192.168.1.250 -P 4006 -usys_admin -pMANAGER maxscale -e"select * from helei;" mysql: [Warning] Using a password on the command line interface can be insecure. +--------+ | a | +--------+ | HE3 | | HE2 | | 写入 | +--------+ [[email protected] ~]# mysql -h192.168.1.250 -P 4006 -usys_admin -pMANAGER maxscale -e"select * from helei;" mysql: [Warning] Using a password on the command line interface can be insecure. +--------+ | a | +--------+ | HE3 | | HE1 | | 写入 | +--------+
在HE1（slave1）恢复完成后，重新有了负载均衡。
Part2:mysql down故障
[[email protected] ~]# /etc/init.d/mysqld stop Shutting down MySQL..... SUCCESS! 停止HE1(slave)可以看到转发到了HE2上 [[email protected] ~]# maxadmin -pmariadb list servers Servers. -------------------+-----------------+-------+-------------+-------------------- Server | Address | Port | Connections | Status -------------------+-----------------+-------+-------------+-------------------- server1 | 192.168.1.248 | 3306 | 0 | Down server2 | 192.168.1.249 | 3306 | 1 | Slave, Running server3 | 192.168.1.250 | 3306 | 1 | Master, Running -------------------+-----------------+-------+-------------+-------------------- [[email protected] ~]# mysql -h192.168.1.250 -P 4006 -usys_admin -pMANAGER mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 28948 Server version: 5.5.5-10.0.0 2.0.1-maxscale MySQL Community Server (GPL) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement. mysql> select @@hostname; +------------+ | @@hostname | +------------+ | HE2 | +------------+ 1 row in set (0.00 sec) 停掉2台slave，观察maxscale的状态 [[email protected] ~]# maxadmin -pmariadb list servers Servers. -------------------+-----------------+-------+-------------+-------------------- Server | Address | Port | Connections | Status -------------------+-----------------+-------+-------------+-------------------- server1 | 192.168.1.248 | 3306 | 0 | Running server2 | 192.168.1.249 | 3306 | 0 | Running server3 | 192.168.1.250 | 3306 | 0 | Master, Stale Status, Running -------------------+-----------------+-------+-------------+--------------------
Warning:警告这里我并没有在
[MySQL Monitor]中配置detect_stale_master=true
可以看出，在maxscale2.0中，已经默认从库都停掉，也不影响
Java Druid注意事项
------------以下文章取材于贺春旸技术博客-------------------
http://hcymysql.blog.51cto.com/5223301/1869414
现象：
程序会不定时的出现连接错误，问题bug的异常信息如下：
The last packet successfully received from the server was 116 milliseconds ago. The last packet sent successfully to the server was 115 milliseconds ago.
java.sql.SQLException: No database selected
但通过客户端sqlyog/navicat连接均为正常。
----------------------------------------------------------------------
另：maxscale1.4.3有时还会出现挂起现象，4006端口直接关闭。后我们用了watch命令后台跑监控。
watch -d /bin/bash /root/sh/restart_maxsacle.sh
1 2 3 4 5 6 7 | #!/bin/bashnetstat -ntlp | grep maxscale | grep 4006 > /dev/null 2>&1if [ $? -eq 1 ];then/etc/init.d/maxscale startfi |
解决：5.6以下可以直接在url上配置：autoReconnect=true
对于5.6以上的只能在jdbc的链接池里设置：
第一个设置成ture,超时自动链接，对于mysql要把第二个设置成false，不启用缓存。
以上是开发需要注意的都是一些基本的配置。
其目的为：每次归还连接时执行select ‘x‘检测连接是否有效。
——总结——
maxscale的核心就在于内个配置文件，根据不同的业务和架构，做好相应的配置，本文意在抛砖引玉，如果您有更全的配置文件，欢迎您分享给笔者。由于笔者的水平有限，编写时间也很仓促，文中难免会出现一些错误或者不准确的地方，不妥之处恳请读者批评指正。
本文出自 “贺磊” 博客，请务必保留此出处http://suifu.blog.51cto.com/9167728/1869520
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