Linux MySQL 修改数据和binlog文件目录

概述

系统：CentOS7.6

MySQL数据库安装，默认数据库文件和binlog文件都在/var/lib/mysql目录下，若Linux系统安装时，未为根目录分配较大硬盘空间，很容易导致系统根目录硬盘空间不够用，从而导致MySQL服务或系统卡死或挂掉。

故需要修改MySQL数据库文件和binlog文件目录。

步骤

1、停止MySQL服务

root用户登录。

service mysqld stop

2、复制默认MySQL数据目录

只复制/var/lib/mysql目录，/var/lib/mysql-files 和 /var/lib/mysql-keyring 目录不动。

# 复制
cp -r /var/lib/mysql /home/mysql

# 修改用户组
chown -R mysql:mysql /home/mysql

# 将默认目录改名，防止误解
mv /var/lib/mysql /var/lib/mysql_bak_origin

3、修改MySQL配置文件

修改MySQL配置文件( /etc/my.cnf )中数据和binlog所在目录和MySQL网络配置文件。

4、修改MySQL服务启动文件

将 /usr/bin/mysqld_pre_systemd 文件中所有的/var/lib/mysql 修改为/home/mysql,以及把76行/var/lib修改为/home。

先备份文件：

cp /usr/bin/mysqld_pre_systemd /usr/bin/mysqld_pre_systemd_bak_origin

然后vim或gedit打开/usr/bin/mysqld_pre_systemd文件修改如下：

#! /bin/bash

# Copyright (c) 2015, 2022, Oracle and/or its affiliates.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License, version 2.0,
# as published by the Free Software Foundation.
#
# This program is also distributed with certain software (including
# but not limited to OpenSSL) that is licensed under separate terms,
# as designated in a particular file or component or in included license
# documentation.  The authors of MySQL hereby grant you an additional
# permission to link the program and your derivative works with the
# separately licensed software that they have included with MySQL.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License, version 2.0, for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA


# Script used by systemd mysqld.service to run before executing mysqld

get_option () {
    local section=$1
    local option=$2
    local default=$3
    local instance=$4
    ret=$(/usr/bin/my_print_defaults  ${instance:+--defaults-group-suffix=@$instance} $section | \
	      grep '^--'${option}'=' | cut -d= -f2- | tail -n 1)
    [ -z "$ret" ] && ret=$default
    echo $ret
}

install_validate_password_sql_file () {
    local initfile
    initfile="$(mktemp /var/lib/mysql-files/install-validate-password-plugin.XXXXXX.sql)"
    chmod a+r "$initfile"
    echo "SET @@SESSION.SQL_LOG_BIN=0;" > "$initfile"
    echo "INSERT INTO mysql.component (component_id, component_group_id, component_urn) VALUES (1, 1, 'file://component_validate_password');" >> $initfile
    echo $initfile
}

fix_mysql_upgrade_info () {
    #datadir=$(get_option mysqld datadir "/var/lib/mysql${instance:+-$instance}" $instance)
    datadir=$(get_option mysqld datadir "/home/mysql${instance:+-$instance}" $instance)
    if [ -d  "$datadir" ]  && [ -O "$datadir/mysql_upgrade_info" ]; then
	chown --reference="$datadir" "$datadir/mysql_upgrade_info"
	if [ -x /usr/bin/chcon ]; then
            /usr/bin/chcon --reference="$datadir" "$datadir/mysql_upgrade_info" > /dev/null 2>&1
	fi
    fi
}

install_db () {
    # Note: something different than datadir=/var/lib/mysql requires SELinux policy changes (in enforcing mode)

    # mysql_upgrade_info file should be owned by mysql user since MySQL 8.0.16
    fix_mysql_upgrade_info

    # No automatic init wanted
    [ -e /etc/sysconfig/mysql ] && . /etc/sysconfig/mysql
    [ -n "$NO_INIT" ] && exit 0

    local instance=$1
    #datadir=$(get_option mysqld datadir "/var/lib/mysql${instance:+-$instance}" $instance)
    datadir=$(get_option mysqld datadir "/home/mysql${instance:+-$instance}" $instance)
    log=$(get_option mysqld 'log[_-]error' "/var/log/mysql${instance:+-$instance}.log" $instance)

    # Restore log, dir, perms and SELinux contexts

    #if [ ! -d "$datadir" -a ! -h "$datadir" -a "x$(dirname "$datadir")" = "x/var/lib" ]; then
    if [ ! -d "$datadir" -a ! -h "$datadir" -a "x$(dirname "$datadir")" = "x/home" ]; then
	install -d -m 0751 -omysql -gmysql "$datadir" || exit 1
    fi

    if [ ! -e "$log" -a ! -h "$log" -a x$(dirname "$log") = "x/var/log" ]; then
	case $(basename "$log") in
	    mysql*.log) install /dev/null -m0640 -omysql -gmysql "$log" ;;
	    *) ;;
	esac
    fi

    if [ -x /usr/sbin/restorecon ]; then
        /usr/sbin/restorecon "$datadir"
        [ -e "$log" ] && /usr/sbin/restorecon "$log"
	for dir in /var/lib/mysql-files /var/lib/mysql-keyring ; do
            #if [ -x /usr/sbin/semanage -a -d /var/lib/mysql -a -d $dir ] ; then
            if [ -x /usr/sbin/semanage -a -d /home/mysql -a -d $dir ] ; then
                #/usr/sbin/semanage fcontext -a -e /var/lib/mysql $dir >/dev/null 2>&1
                /usr/sbin/semanage fcontext -a -e /home/mysql $dir >/dev/null 2>&1
                /sbin/restorecon -r $dir
            fi
	done
    fi

    # If special mysql dir is in place, skip db install
    [ -d "$datadir/mysql" ] && exit 0

    # Create initial db and install validate_password plugin
    initfile="$(install_validate_password_sql_file)"
    /usr/sbin/mysqld ${instance:+--defaults-group-suffix=@$instance} --initialize \
		     --datadir="$datadir" --user=mysql --init-file="$initfile"
    rm -f "$initfile"

    # Generate certs if needed
    if [ -x /usr/bin/mysql_ssl_rsa_setup -a ! -e "${datadir}/server-key.pem" ] ; then
        /usr/bin/mysql_ssl_rsa_setup --datadir="$datadir" --uid=mysql >/dev/null 2>&1
    fi
    exit 0
}

install_db $1

exit 0