mysql upgrade 5 to 8

Backup

• mkdir mysqlbk
• mysqldump ---all-databases --routines --events > ~/mysqlbk/mysql_backup.sql
• cp /etc/my.cnf ~/mysqlbk/my.cnf
• cp -R /etc/my.cnf.d/ ~/mysqlbk/etc_my.cnf.d/
• cp -R /var/lib/mysql/ ~/mysqlbk/var_lib_mysql/
• mysql -u -p
  mysql> open mysql
  mysql> SELECT User, Host FROM mysql.user;  # list user and backup

Upgrade

• rpm -e --nodeps mysql57-community-release
• yum update -y
• rpm --import https://repo.mysql.com/RPM-GPG-KEY-mysql-2023
• yum install -y https://repo.mysql.com/mysql84-community-release-el7-1.noarch.rpm
• yum makecache
• systemctl stop mysqld.service
• yum remove -y mysql-community-client-5.7* mysql-community-common-5.7* mysql-community-libs-5.7* mysql-community-server-5.7* 
• yum install mysql-community-server
• systemctl start mysqld.service

ERROR:Data Dictionary initialization failed.

• rm -rf /var/lib/mysql
• mysqld --initialize --console
• chown -R mysql:mysql /var/lib/mysql
• systemctl start mysqld

Config

• grep 'temporary password' /var/log/mysqld.log
• mysql_secure_installation