技术分享 | MySQL 主机该如何配置 fs.aio-max-nr

MySQL 默认是启用 innodb_use_native_aio，使用异步 IO *** 作，MySQL 启动时所需 aio slot 若超过系统当前 fs.aio-max-nr 设置，则无法启动报错 InnoDB: io_setup() failed with EAGAIN after 5 attempts.

通常在单机单实例环境下很少会遇到超出 aio-max-nr 的问题，若部署单机多实例，会大概率遇到此问题。我们来分析下该如何配置 fs.aio-max-nr 参数。关于 aio-nr 与 aio-max-nr

使用 strace 观测 io_setup 调用情况，

总共：4709 个 = 18 * 256 + 101

其分配 256 event 的也就是 InnoDB IO 线程。

MySql安装

yum -y install libaio

wget https://cdn.mysql.com//Downloads/MySQL-5.7/mysql-5.7.24-linux-glibc2.12-x86_64.tar.gz

cd /usr/local/soft/mysql/src

mkdir ../5.7.24_3306 &&tar -xzvf mysql-5.7.24-linux-glibc2.12-x86_64.tar.gz -C ../5.7.24_3306 --strip-components 1

mkdir -p /usr/local/soft/mysql/5.7.24_3306/{run,data,logs,bin_log,sock,cert}

groupadd mysql &&useradd -r -g mysql -s /bin/false mysql

cd /usr/local/soft/mysql/5.7.24_3306/bin &&./mysqld --initialize

--explicit_defaults_for_timestamp

--user=mysql

--basedir=/usr/local/soft/mysql/5.7.24_3306

--datadir=/usr/local/soft/mysql/5.7.24_3306/data

--lc_messages_dir=/usr/local/soft/mysql/5.7.24_3306/share

--lc_messages=en_US

2018-12-01T09:56:45.934627Z 0 [Warning] InnoDB: New log files created, LSN=45790

2018-12-01T09:56:46.056837Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.

2018-12-01T09:56:46.127141Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 69d028f9-f54f-11e8-9c4a-00163e08e793.

2018-12-01T09:56:46.130249Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.

2018-12-01T09:56:46.131377Z 1 [Note] A temporary password is generated for root@localhost: sDdPx3>.,oBi

cd /usr/local/soft/mysql/5.7.24_3306/bin &&./mysql_ssl_rsa_setup --datadir=/usr/local/soft/mysql/5.7.24_3306/cert

修改证书权限为644

cd /usr/local/soft/mysql/5.7.24_3306/bin &&./mysql -uroot -S /usr/local/soft/mysql/5.7.24_3306/sock/mysql.sock

use mysql

update user set host = '%', authentication_string = password('123456') where user = 'root'

select host,user,authentication_string from user

flush privileges

grant all privileges on . to 'root'@'%'

flush privileges

cat >/etc/systemd/system/3306.service <<EOF

[Unit]

Description=MySQL 3306

Documentation= http://dev.mysql.com/doc/refman/en/using-systemd.html

After=network.target remote-fs.target nss-lookup.target

[Service]

Type=forking

PIDFile=/usr/local/soft/mysql/5.7.24_3306/run/mysql.pid

ExecStart=/usr/local/soft/mysql/5.7.24_3306/support-files/mysql.server start

ExecReload=/usr/local/soft/mysql/5.7.24_3306/support-files/mysql.server restart

ExecStop=/usr/local/soft/mysql/5.7.24_3306/support-files/mysql.server stop

PrivateTmp=true

[Install]

WantedBy=multi-user.target

EOF

systemctl enable 3306.service

1、

cd /usr/local/soft/mysql/5.7.24.3306/bin &&./mysqld_safe --skip-grant-tables &

cd /usr/local/soft/mysql/5.7.24.3306/bin &&./mysqld_safe --skip-grant-tables --skip-networking &

2、

./mysql -uroot -p -S /usr/local/soft/mysql/5.7.24.3306/sock/mysql.sock

3、

use mysql

update mysql.user set authentication_string=password('123456') where user='root'

flush privileges

mkdir -p /usr/local/soft/mysql/back/5.7.23_3306 &&cp -Rf /usr/local/soft/mysql/5.7.23_3306/* /usr/local/soft/mysql/back/5.7.23_3306

mkdir -p /usr/local/soft/mysql/back/5.7.24_3306 &&cp -Rf /usr/local/soft/mysql/5.7.24_3306/* /usr/local/soft/mysql/back/5.7.24_3306

CREATE USER 'sdyc'@'%' IDENTIFIED BY '123456'

GRANT SELECT, INSERT, UPDATE, DELETE, EXECUTE ON sd_data.* TO 'sdyc'@'%'

GRANT SELECT, INSERT, UPDATE, DELETE, EXECUTE ON card_data.* TO 'sdyc'@'%'

SHOW GRANTS FOR sdyc

CREATE USER 'back'@'localhost' IDENTIFIED BY '123456'

GRANT SELECT, RELOAD, PROCESS, SHOW DATABASES, SUPER, LOCK TABLES, REPLICATION CLIENT ON . TO 'back'@'localhost'

SHOW GRANTS FOR back

REVOKE SELECT, INSERT, UPDATE, DELETE, EXECUTE ON sd_data.* FROM 'sdyc'@'%'

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