MySQL單機(jī)多案例分享

1. 安裝MySQL

系統(tǒng): Ubuntu 16.04LTS (xenial)
版本: Percorna Server 5.7.21-20
安裝: 官網(wǎng)教程

2. mysqld_multi配置文件

新建一個(gè)文件 /etc/mysql/multi_server.cnf

[mysqld_multi]
# 如果MySQL服務(wù)不是通過mysqld_safe啟動(dòng)的,這個(gè)要注釋掉
#mysqld = /usr/bin/mysqld_safe
mysqladmin = /usr/bin/mysqladmin
user = multi_admin
password = 123456
[mysqld1]
user = mysql
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
port = 3306
basedir = /usr
datadir = /var/lib/mysql
tmpdir = /tmp
[mysqld2]
user = mysql
pid-file=/var/run/mysqld/mysql.pid2
socket=/var/run/mysqld/mysqld.sock2
port = 3307
basedir = /usr
datadir = /var/lib/mysql2

3. 啟動(dòng)服務(wù)

查看實(shí)例運(yùn)行
mysqld_multi --defaults-file=/etc/mysql/multi_server.cnf report

啟動(dòng)服務(wù)
mysqld_multi --defaults-file=/etc/mysql/multi_server.cnf start

因?yàn)橐话闱闆r,第一個(gè)已經(jīng)是我們安裝好,而且root用戶也設(shè)置好的,所以不太可能出問題.
mysql2可能出現(xiàn)的問題:

FATAL ERROR: Tried to start mysqld under group [mysqld2], but no data directory was found or could be created. data directory used: /var/lib/mysql2

MySQL5.7 新增實(shí)例的命令行如下

mysqld --datadir=/var/lib/mysql2 --initialize --initialize-insecure ...
官網(wǎng)鏈接

再看/usr/bin/mysqld_multi 腳本343行上下

            print "\n\nInstalling new database in $datadir\n\n";
            $install_cmd="/usr/bin/mysqld ";
            $install_cmd.="--initialize ";
            $install_cmd.="--user=mysql ";
            $install_cmd.="--datadir=$datadir";

咋一看好像沒什么問題,實(shí)際上,用命令行執(zhí)行

which mysqld
得到的結(jié)果
/usr/sbin/mysqld

所以把這個(gè)腳本修改之后,就能正常啟動(dòng)了.
當(dāng)然,如果還不行的話,可能要考慮一下用戶權(quán)限問題
如果使用Ubuntu的話,可能還要查看是否apparmor的權(quán)限限制

接上面,如果就這樣啟動(dòng)的話,mysql2 實(shí)例會(huì)隨機(jī)給root用戶建一個(gè)隨機(jī)密碼,導(dǎo)致后續(xù)客戶端無法登錄該實(shí)例.如果需要找回密碼,只能通過error_log
這時(shí),同樣需要修改腳本,在腳本中加上參數(shù)"--initialize-insecure",注意參數(shù)間的空格.
建立連接之后,再執(zhí)行

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'new_password';

4. 后續(xù)操作

給root用戶加權(quán)限

GRANT ALL PRIVILEGES ON . TO root@'%' IDENTIFIED BY "123456";
flush privileges;

在各個(gè)實(shí)例給mysqld_multi管理用戶multi_admin 加上shutdown權(quán)限

GRANT SHUTDOWN ON . TO multi_admin@localhost IDENTIFIED BY 'password';

如果通過mysqld_multi stop 無法有效關(guān)閉實(shí)例,可以通過mysqladmin 直接shutdown

后續(xù)如果因?yàn)椴僮鞑划?dāng)導(dǎo)致實(shí)例無法啟動(dòng),可以通過命令查看錯(cuò)誤日志

tail -30 /var/log/mysql/error.log

常見問題

2018-02-22T02:02:28.227868Z 0 [ERROR] /usr/sbin/mysqld: Can't create/write to file '/var/run/mysqld/mysql.pid3' (Errcode: 13 - Permission denied)
2018-02-22T02:02:28.227889Z 0 [ERROR] Can't start server: can't create PID file: Permission denied

這時(shí),可以看到/var/run/mysqld 文件夾如下,把文件都刪除,再重啟一下就可以了

-rw-r--r-- 1 root root 0 Feb 22 02:01 mysqld.pid
-rw-r--r-- 1 root root 0 Feb 21 15:35 mysqld.pid2
srwxrwxrwx 1 mysql mysql 0 Feb 22 02:02 mysqld.sock=
srwxrwxrwx 1 mysql mysql 0 Feb 22 02:02 mysqld.sock2=
-rw------- 1 mysql mysql 6 Feb 22 02:02 mysqld.sock2.lock
srwxrwxrwx 1 mysql mysql 0 Feb 22 02:02 mysqld.sock3=
-rw------- 1 mysql mysql 6 Feb 22 02:02 mysqld.sock3.lock
-rw------- 1 mysql mysql 6 Feb 22 02:02 mysqld.sock.lock
-rw-r--r-- 1 root root 0 Feb 22 02:01 mysql.pid2
-rw-r--r-- 1 root root 0 Feb 22 02:01 mysql.pid3

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