背景：
前面的2篇文章MySQL ProxySQL读写分离使用初探和MySQL ProxySQL读写分离实践大致介绍了ProxySQL的使用说明，从文章的测试的例子中看到ProxySQL使用SQLITE来进行配置的持久化，以及ProxySQL是一个CPU密集型的中间价，如果CPU比较空闲，可以像MySQL一样安装多个实例的ProxySQL，充分利用资源。下面介绍下如何备份持久化的ProxySQL配置和多实例ProxySQL的创建。
多实例建立：
假设默认的实例已经装好了（6032、6033），现在需要新增一个新实例（ProxySQL2）：7032，7033
1，添加配置文件：
cp /etc/proxysql.cnf /etc/proxysql2.cnf
2，修改配置文件：修改3行
datadir="/var/lib/proxysql2"
...
...
mysql_ifaces="127.0.0.1:7032;/tmp/proxysql_admin2.sock"
...
...
interfaces="0.0.0.0:7033;/tmp/proxysql2.sock"
...
3，添加启动文件：
cp /etc/init.d/proxysql /etc/init.d/proxysql2
4，修改启动文件：
OLDDATADIR="/var/run/proxysql2"
DATADIR="/var/lib/proxysql2"
OPTS="-c /etc/proxysql2.cnf -D $DATADIR" 修改成新的启动
sudo -u proxysql /usr/bin/proxysql2 $OPTS 修改2行：
for i in `pgrep proxysql` ; do
替换为：
for i in `pidof proxysql2` ; do 最后修改一些输出：
把echo输出的proxysql改成proxysql2
5，复制执行文件（懒的修改脚本了，直接复制新起一个执行文件...）：
cp /usr/bin/proxysql /usr/bin/proxysql2
这里需要注意的是：需要修改默认实例的启动文件（/etc/init.d/proxysql）
修改2行：
for i in `pgrep proxysql` ; do
替换为：
for i in `pidof proxysql` ; do
即把pgrep改成pidof，这是因为通过pgrep找到了所有的proxysql实例的进程号，会引起误操作，单实例ProxySQL可以不需要考虑。
6，修改权限：
chown -R proxysql.proxysql proxysql2.cnf
chown -R proxysql.proxysql proxysql2/
7，开启实例：
root@dbproxy:/var/lib# /etc/init.d/proxysql2 start
Starting ProxySQL2: DONE!
root@dbproxy:/var/lib# ps -ef| grep proxy
proxysql May27 ? :: /usr/bin/proxysql -c /etc/proxysql.cnf -D /var/lib/proxysql
proxysql May27 ? :: /usr/bin/proxysql -c /etc/proxysql.cnf -D /var/lib/proxysql
proxysql : ? :: /usr/bin/proxysql2 -c /etc/proxysql2.cnf -D /var/lib/proxysql2
proxysql : ? :: /usr/bin/proxysql2 -c /etc/proxysql2.cnf -D /var/lib/proxysql2
查看端口信息：
root@dbproxy2:/var/lib# netstat -nltp
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 127.0.0.1: 0.0.0.0:* LISTEN /proxysql
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql
tcp 0.0.0.0: 0.0.0.0:* LISTEN /sshd
tcp 127.0.0.1: 0.0.0.0:* LISTEN /proxysql2
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql2
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql2
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql2
tcp 0.0.0.0: 0.0.0.0:* LISTEN /proxysql2
tcp6 ::: :::* LISTEN /sshd
8：完成
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 stop
Shutting down ProxySQL2: DONE!
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 start
Starting ProxySQL2: DONE!
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 status
ProxySQL2 is running ().
root@dbproxy2:/var/lib/proxysql2# mysql -uadmin -padmin -h127.0.0. -P7032
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
Server version: 5.5. (ProxySQL Admin Module) Copyright (c) - Percona LLC and/or its affiliates
Copyright (c) , , 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. admin@127.0.0.1 : (none) ::>select * from mysql_servers;
Empty set (0.00 sec) admin@127.0.0.1 : (none) ::>
到此，多实例已经建立成功，接着说明下如何对持久化的配置进行备份。
持久化配置备份
上面已经提到，ProxySQL的持久化是通过SQLITE实现的，对于备份就是对SQLITE的备份，关于如何使用SQLITE可以查看官方文档和SQLite教程。这里大致的说明下sqlite以 SQL 文本格式转储数据。
1：先到指定的数据db目录
root@dbproxy:/var/lib/proxysql# ls -lh
-rw------- proxysql proxysql 33K May : proxysql.db
-rw------- proxysql proxysql 142K May : proxysql.log
-rw-r--r-- proxysql proxysql May : proxysql.pid
2：备份，执行.dump
root@dbproxy:/var/lib/proxysql# sqlite3 proxysql.db .dump > /home/dxy/proxysql.sql
3，还原，若还原到另一个ProxySQL（上面安装的实例proxysql2）中，先保证目标proxysql.db文件不存在(需要关闭ProxySQL，删除数据目录里的所有文件）再执行：
root@dbproxy:~# /etc/init.d/proxysql2 stop
Shutting down ProxySQL2: DONE! root@dbproxy:/var/lib/proxysql2# ls -lh
total
在目标实例目录中执行：
root@dbproxy:/var/lib/proxysql2# sqlite3 proxysql.db < /home/dxy/proxysql.sql
root@dbproxy:/var/lib/proxysql2# ls -lh
total 32K
-rw-r--r-- root root 32K May : proxysql.db
开启实例：
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 start
Starting ProxySQL: DONE!
root@dbproxy:/var/lib/proxysql2# ls -lh
total 60K
-rw-r--r-- root root 32K May : proxysql.db
-rw------- proxysql proxysql 21K May : proxysql.log
-rw-r--r-- proxysql proxysql May : proxysql.pid #修改权限
root@dbproxy:/var/lib/proxysql2# chown -R proxysql.proxysql proxysql.db
说明：如果备份的实例和还原的实例使用的端口全部一致，则直接开启ProxySQL就可以用了。但本文的测试备份的实例的端口是6032和6033，还原的目标实例端口是7032和7033，即使还原了也不能使用，所以需要修改db文件，用sqlite连接修改：
#连接
root@dbproxy:/var/lib/proxysql2# sqlite3 proxysql.db #修改显示
sqlite> .header on
sqlite> .mode column #查看需要更新的变量
sqlite> select * from global_variables;
...
admin-mysql_ifaces 127.0.0.1:
...
mysql-interfaces 0.0.0.0:;/ #更新
sqlite> update global_variables set variable_value='127.0.0.1:7032' where variable_name = 'admin-mysql_ifaces';
sqlite> update global_variables set variable_value='0.0.0.0:7033;/' where variable_name = 'mysql-interfaces';
上面操作完成之后，再开启ProxySQL验证：
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 start
Starting ProxySQL2: DONE! oot@dbproxy2:/var/lib/proxysql2# mysql -uadmin -padmin -h127.0.0. -P7032
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
Server version: 5.5. (ProxySQL Admin Module) Copyright (c) - Percona LLC and/or its affiliates
Copyright (c) , , 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. admin@127.0.0.1 : (none) ::>select * from mysql_users;
+-----------+-------------------------------------------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
| username | password | active | use_ssl | default_hostgroup | default_schema | schema_locked | transaction_persistent | fast_forward | backend | frontend | max_connections |
+-----------+-------------------------------------------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
| abc | *1AF30A6370D8959926FC3BD6158C9C551D0DBA28 | | | | | | | | | | |
| bcd | *F8258EA2FA1D7FE2B55DA522BFCC87B93CC63ADF | | | | | | | | | | |
+-----------+-------------------------------------------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
rows in set (0.00 sec) admin@127.0.0.1 : (none) ::>select * from mysql_servers;
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-----------+
| hostgroup_id | hostname | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-----------+
| | 192.168.20.123 | | ONLINE | | | | | | | ReadWrite |
| | 192.168.20.12 | | ONLINE | | | | | | | ReadOnly |
| | 192.168.20.123 | | ONLINE | | | | | | | ReadWrite |
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-----------+
rows in set (0.00 sec)
从上面的结果看到，持久化备份和还原成功。注意：因为sqlite不支持远程备份，需要在本地备份好之后，再传到备份中心进行保存。
总结：
到此，关于ProxySQL的介绍告已段落，ProxySQL作者的更新还是比较勤快的，若后续有新功能和特性等，再进行补充说明，关于ProxySQL的文档请见：https://github.com/sysown/ProxySQL。