I previously installed MySQL built-in 5.1 and it worked well. Today, I followed this article and installed 5.7. Unfortunately, my VM has limited ram (512mb) and 5.7 cannot be started. I would like to downgrade MySQL to my working version 5.1. I did remove 5.7 by using yum remove mysql successfully. But then: # yum download mysqlNo Match for available package: mysql-5.1.73-8.el6_8.i686Nothing to doIf I run yum install mysql, it reinstall 5.7 version again. How can I reinstall mysql 5.1?Log from file mysqld.log.rpmsave170620 23:48:04  InnoDB: Starting shutdown...170620 23:48:10  InnoDB: Shutdown completed; log sequence number 0 34058928170620 23:48:10 [Note] 170620 23:48:10 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended170620 23:54:27 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql170620 23:54:27 [ERROR] Can't read from messagefile '/usr/share/mysql/english/errmsg.sys'170620 23:54:27  InnoDB: Initializing buffer pool, size = 8.0M170620 23:54:27  InnoDB: Completed initialization of buffer pool170620 23:54:27  InnoDB: Started; log sequence number 0 34058928170620 23:54:27 [ERROR] /usr/libexec/mysqld: unknown variable 'innodb_large_prefix=true'170620 23:54:27 [ERROR] Aborting170620 23:54:27  InnoDB: Starting shutdown...170620 23:54:32  InnoDB: Shutdown completed; log sequence number 0 34058928170620 23:54:32 [Note] 170620 23:54:32 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid endedLog from file messagesJun 21 00:46:03 vpn1UgoVPNcom kernel: Out of memory: Kill process 31276 (mysqld) score 162 or sacrifice childJun 21 00:46:03 vpn1UgoVPNcom kernel: Killed process 31276, UID 0, (mysqld) total-vm:126948kB, anon-rss:98224kB, file-rss:8kBThere is no such file mysqld.err , also Mysqld.log is emptyAttempting to start MySQL 5.7[root@vpn1UgoVPNcom home]# service mysqld start/usr/bin/mysqld_safe: line 196:  9475 Killed                  nohup /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock < /dev/null > /dev/null 2>&1MySQL Daemon failed to start.Starting mysqld:                                           [FAILED]
Downgrade MySQL 5.7 to 5.1 in CentOS 6
centos;yum;mysql