mysql数据库的多实例与主从同步。

1、mysql的多实例：
多实例的特点：能够有效地利用服务器的资源，节约服务器的资源
mysql多实例的配置有两种，第一是使用一个配置文件，这种方法不推荐使用，容易出错；第二种是用多个配置文件，这种方法的好处是可以方便管理。
[root@localhost 3308]# tree -l 2 /data/
/data/
├── 3307
│   ├── data
│   ├── my.cnf
│   ├── mysql
│   ├── mysql_3307.err
│   ├── mysqld.pid
│   └── mysql.sock
└── 3308
    ├── data
    ├── my.cnf
    ├── mysql
    ├── mysql_3308.err
    ├── mysqld.pid
    └── mysql.sock

安装mysql
通过压缩包哦安装，提前下载mysql-5.5.62-linux-glibc2.12-x86_64.tar.gz，解压即可。
添加mysql用户，
useradd -s /sbin/nologin mysql

将解压的文件移动到/usr/local并做软连接
mv mysql-5.5.62-linux-glibc2.12-x86_64 /usr/local
ln -s mysql-5.5.62-linux-glibc2.12-x86_64 /usr/local/mysql

创建每个服务端口的data文件夹
mkdir -p /data/{3307,3308}

进行mysql初始化：
./scripts/mysql_install_db --user=mysql --basedir=/application/mysql/ --datadir=/data/3307/data
./scripts/mysql_install_db --user=mysql --basedir=/application/mysql/ --datadir=/data/3308/data

配置端口的配置文件my.cnf
vim /data/3307/my.cnf
vim /data/3308/my.cnf
[3307/my.cnf]
[client]
port            = 3307
socket          = /data/3307/mysql.sock

[mysql]
no-auto-rehash

[mysqld]
user    = mysql
port    = 3307
socket  = /data/3307/mysql.sock
basedir = /application/mysql
datadir = /data/3307/data
open_files_limit    = 1024
back_log = 600
max_connections = 800
max_connect_errors = 3000
table_cache = 614
external-locking = false
max_allowed_packet =8m
sort_buffer_size = 1m
join_buffer_size = 1m
thread_cache_size = 100
thread_concurrency = 2
query_cache_size = 2m
query_cache_limit = 1m
query_cache_min_res_unit = 2k
#default_table_type = innodb
thread_stack = 192k
#transaction_isolation = read-committed
tmp_table_size = 2m
max_heap_table_size = 2m
#long_query_time = 1
#log_long_format
#log-error = /data/3307/error.log
#log-slow-queries = /data/3307/slow.log
pid-file = /data/3307/mysql.pid
#log-bin = /data/3307/mysql-bin
relay-log = /data/3307/relay-bin
relay-log-info-file = /data/3307/relay-log.info
binlog_cache_size = 1m
max_binlog_cache_size = 1m
max_binlog_size = 2m
expire_logs_days = 7
key_buffer_size = 16m
read_buffer_size = 1m
read_rnd_buffer_size = 1m
bulk_insert_buffer_size = 1m
#myisam_sort_buffer_size = 1m
#myisam_max_sort_file_size = 10g
#myisam_max_extra_sort_file_size = 10g
#myisam_repair_threads = 1
#myisam_recover

lower_case_table_names = 1
skip-name-resolve
slave-skip-errors = 1032,1062
replicate-ignore-db=mysql

server-id = 8

innodb_additional_mem_pool_size = 4m
innodb_buffer_pool_size = 32m
innodb_data_file_path = ibdata1:128m:autoextend
innodb_file_io_threads = 4
innodb_thread_concurrency = 8
innodb_flush_log_at_trx_commit = 2
innodb_log_buffer_size = 2m
innodb_log_file_size = 4m
innodb_log_files_in_group = 3
innodb_max_dirty_pages_pct = 90
innodb_lock_wait_timeout = 120
innodb_file_per_table = 0
[mysqldump]
quick
max_allowed_packet = 2m

[mysqld_safe]
log-error=/data/3307/mysql_3307.err
pid-file=/data/3307/mysqld.pid
3308的配置文件把3307改成3308

配置各端口的启动文件
vim /data/3307/mysql
vim /data/3308/mysql
[3307/mysql]
#!/bin/bash
# chkconfig: 2345 21 60
# description: msyql start scripts
port=3307
user=root
passwd=123456
path=/application/mysql/bin
#socket=/tmp/mysql.sock
mysqlsock="/data/${port}/mysql.sock"
function_start(){
        if [ -e $mysqlsock  ];then
        echo "mysql already running..."
        else
                $path/mysqld_safe --defaults-file=/data/${port}/my.cnf  &>/dev/null &
                [ $? -eq 0 ]&&{
#               . /etc/init.d/functions
                echo "mysql start success!!!" 
                }
        fi
}

function_stop(){
        if [ -e $mysqlsock ];then
                $path/mysqladmin -u$user -p$passwd -s $mysqlsock shutdown  &>/dev/null &
                [ $? -eq 0 ]&& {
#               . /etc/init.d/functions
                echo  "mysql stop success!!!" 
                }||echo  "mysql stop failed" 
        else
                echo "mysql dont start"
        fi
}
function_restart(){

        if [ -e $socket  ];then
        function_stop
        sleep 2
        function_start
        else
        function_start
fi
}
function_status(){
        [ -e $msyqlsock ]&& echo "mysql is running" || echo "mysql is down"
}
case $1 in
start)
        function_start
;;
stop)
        function_stop
;;
status)
        function_status
;;
restart)
        function_restart
;;
*)
echo "usage |$0{start|stop|status|restart}"
esac
3308的启动文件将port改成3308

将/data多实例文件添加权限
 chown -r mysql.mysql /data/

启动数据库

[root@localhost 3307]# mysqld_safe --defaults-file=/data/3307/my.cnf
/data/3307/mysql start 

进入数据库
[root@localhost ~]# mysql -s /data/3307/mysql.sock 
[root@localhost ~]# netstat -lntup
active internet connections (only servers)
proto recv-q send-q local address           foreign address         state       pid/program name    
tcp        0      0 0.0.0.0:3307            0.0.0.0:*               listen      18787/mysqld        
tcp        0      0 0.0.0.0:3308            0.0.0.0:*               listen      19506/mysqld       

2、mysql的主从复制
mysql数据库的主从复制方案，与使用scp/rsync等命令进行的文件级别复制类似，都是数据的远程传输，只不过mysql的主从复制是其自带的功能，无需借助第三方工具，而且，mysql的主从复制并不是数据库磁盘上的文件直接拷贝，而是通过逻辑的binlog日志复制到要同步的服务器本地，然后由本地的线程读取日志里面的sql语句，重新应用到mysql数据库中。
主从复制原理
1）在slave服务器上执行start slave命令开启主从复制开关，开始进行主从复制
2）此时，slave服务器的i/o线程会通过在master上已经授权的复制用户权限请求连接master服务器，并请求从指定binlog日志文件的指定位置（日志文件名和位置就是在配置主从复制服务时执行change master命令指定的）之后开始发送binlog日志内容。
3）master服务器接收到来自slave服务器的i/o线程的请求后，其上负责复制的i/o线程会根据slave服务器的i/o线程请求的信息分批读取指定binlog日志文件指定位置之后的binlog日志信息，然后返回给slave端的i/o线程。返回的信息中除了binlog日志内容外，还有在master服务器端记录的新的binlog文件名称，以及在新的binlog中的下一个指定更新位置。
4）当slave服务器的i/o线程获取到master服务器上i/o线程发送的日志内容，日志文件及位置点后，会将binlog日志内容依次写到slave端自身的relay log（即中继日志）文件（mysql-relay-bin.xxxx）的最末端，并将新的binlog文件名和位置记录到master-info文件中，以便下一次读取master端新binlog日志时能够告诉master服务器从新binlog日志的指定文件及位置开始请求新的binlog日志内容。
5）slave服务器端的sql线程会实时检测本地relay log中i/o线程新增加的日志内容，然后及时地把relay log文件中的内容解析成sql语句，并在自身slave服务器上按解析sql语句的位置顺序执行应用这些sql语句，并在relay-log.info中记录当前应用中继日志的文件名及位置点。
开启主数据库的log-bin：
#在my.cnf文件里的[mysqld]下编辑：
log-bin = /data/3306/mysql-bin

测试log-bin是否开启：
[root@localhost 3307]# mysql -u root -p -s /data/3306/mysql.sock 
enter password: 
welcome to the mysql monitor.  commands end with ; or \g.
your mysql connection id is 7
server version: 5.5.62 mysql community server (gpl)

copyright (c) 2000, 2018, 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> show variables like 'server_id';
+---------------+-------+
| variable_name | value |
+---------------+-------+
| server_id     | 5     |
+---------------+-------+
1 row in set (0.00 sec)

mysql> show variables like 'log_bin';
+---------------+-------+
| variable_name | value |
+---------------+-------+
| log_bin       | on    |
+---------------+-------+
1 row in set (0.00 sec)

建立用于从库复制的账号yunjisuan
mysql>  grant replication slave on *.* to 'yunjisuan'@'10.6.29.154' identified by 'yunjisuan123';
query ok, 0 rows affected (0.01 sec)
刷新权限
mysql> flush privileges;
query ok, 0 rows affected (0.00 sec)
mysql> select user,host from mysql.user;
+-----------+-----------------------+
| user      | host                  |
+-----------+-----------------------+
| root      | 127.0.0.1             |
| yunjisuan | 10.6.29.154           |
| root      | ::1                   |
|           | localhost             |
| root      | localhost             |
|           | localhost.localdomain |
| root      | localhost.localdomain |
+-----------+-----------------------+
7 rows in set (0.00 sec)

备份主表
[root@localhost ~]# mysqldump -uroot -p123456 -s /data/3306/mysql.sock --events -a -b | gzip >/server/backup/mysql_bak.$(date +%f).sql.gz

查看从数据库的serverid
[root@localhost ~]# egrep "server-id|log-bin" /data/3307/my.cnf
#log-bin = /data/3307/mysql-bin
server-id = 2

查看从数据的状态

mysql> show variables like 'log_bin';
+---------------+-------+
| variable_name | value |
+---------------+-------+
| log_bin       | off   |
+---------------+-------+
1 row in set (0.00 sec)

mysql> show variables like 'server_id';
+---------------+-------+
| variable_name | value |
+---------------+-------+
| server_id     | 2     |
+---------------+-------+
1 row in set (0.00 sec)

解压主数据库备份文件
[root@localhost backup]# gzip -d mysql_bak.2019-09-11.sql.gz 
把数据还原到3307
[root@localhost backup]# mysql -u root -p123456 -s /data/3307/mysql.sock <mysql_bak.2019-09-11.sql 

登录从库，配置复制参数
mysql> show master status
    -> ;
+------------------+----------+--------------+------------------+
| file             | position | binlog_do_db | binlog_ignore_db |
+------------------+----------+--------------+------------------+
| mysql-bin.000002 |      107 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
mysql> change master to master_host='10.6.29.154',master_port=3306,master_user='yunjisuan',master_password='yunjisuan123',master_log_file='mysql-bin.000001',master_log_pos=345;
query ok, 0 rows affected (0.01 sec)

开启主从同步开关，并查看
[root@localhost backup]#  mysql -uroot -p123456 -s /data/3307/mysql.sock -e "start slave"
[root@localhost backup]# mysql -uroot -p123456 -s /data/3307/mysql.sock -e "show slave status\g"
*************************** 1. row ***************************
               slave_io_state: waiting for master to send event
                  master_host: 10.6.29.154
                  master_user: yunjisuan
                  master_port: 3306
                connect_retry: 60
              master_log_file: mysql-bin.000002
          read_master_log_pos: 107
               relay_log_file: relay-bin.000002
                relay_log_pos: 253
        relay_master_log_file: mysql-bin.000002
             slave_io_running: yes
            slave_sql_running: yes
              replicate_do_db: 
          replicate_ignore_db: mysql
           replicate_do_table: 
       replicate_ignore_table: 
      replicate_wild_do_table: 
  replicate_wild_ignore_table: 
                   last_errno: 0
                   last_error: 
                 skip_counter: 0
          exec_master_log_pos: 107
              relay_log_space: 403
              until_condition: none
               until_log_file: 
                until_log_pos: 0
           master_ssl_allowed: no
           master_ssl_ca_file: 
           master_ssl_ca_path: 
              master_ssl_cert: 
            master_ssl_cipher: 
               master_ssl_key: 
        seconds_behind_master: 0
master_ssl_verify_server_cert: no
                last_io_errno: 0
                last_io_error: 
               last_sql_errno: 0
               last_sql_error: 
  replicate_ignore_server_ids: 
             master_server_id: 5
1 row in set (0.00 sec)


随后在主库创建数据库等，再到从库查看：
[root@localhost backup]# mysql -uroot -p123456 -s /data/3306/mysql.sock -e "create database admin1;"
[root@localhost backup]# mysql -uroot -p123456 -s /data/3307/mysql.sock -e "show databases;"
+--------------------+
| database           |
+--------------------+
| information_schema |
| admin1             |
| mysql              |
| performance_schema |
| test               |
+--------------------+


这样就完成了mysql数据库的主从同步。