MySQL运行多实例有2种方法，第一种是使用多个配置文件启动不同的进程来实现多实例;第二种是通过mysqld_multi使用单独的配置文件来实现多实例
环境准备：
操作系统：Red Hat Enterprise Linux Server release 6.5 (Santiago)
MySQL版本：mysql-5.6.22-linux-glibc2.5-x86_64
要运行多实例，首先安装MySQL软件，安装方法参考之前的博文：MySQL安装，安装好MySQL软件之后，下面分别创建端口分别为3306,3307,3308，3309的多实例，无论使用哪种方式来管理多实例，都是需要初始化多个数据库的
一、使用多个配置文件来管理多实例
1、创建各实例的配置文件
# mkdir /data/mysql/conf/ -p
# cd /data/mysql/conf/
# vim my_3306.cnf
[client]
port = 3306
socket = /tmp/mysql_3306.sock
[mysql]
prompt="\\u@\\h:\p \\R:\\m:\\s [\\d]>"
#tee=/data/mysql/mysql_3306/query.log
no-auto-rehash
[mysqld]
#misc
user = mysql
basedir = /usr/local/mysql
datadir = /data/mysql/mysql_3306
port = 3306
socket = /tmp/mysql_3306.sock
event_scheduler = 0
#timeout
interactive_timeout = 300
wait_timeout = 300
#character set
character-set-server = utf8
open_files_limit = 65535
max_connections = 100
max_connect_errors = 100000
skip-name-resolve = 1
#logs
log-output=file
slow_query_log = 1
slow_query_log_file = slow.log
log-error = error.log
log_warnings = 2
pid-file = mysql.pid
long_query_time = 1
#log-slow-admin-statements = 1
#log-queries-not-using-indexes = 1
log-slow-slave-statements = 1
#binlog
binlog_format = row
server-id = 883306
log-bin =mysql-bin
binlog_cache_size = 4M
max_binlog_size = 1G
max_binlog_cache_size = 2G
sync_binlog = 0
expire_logs_days = 10
#relay log
skip_slave_start = 1
max_relay_log_size = 1G
relay_log_purge = 1
relay_log_recovery = 1
log_slave_updates
#slave-skip-errors=1032,1053,1062
explicit_defaults_for_timestamp=true
#buffers & cache
table_open_cache = 2048
table_definition_cache = 2048
table_open_cache = 2048
max_heap_table_size = 96M
sort_buffer_size = 2M
join_buffer_size = 2M
thread_cache_size = 256
query_cache_size = 0
query_cache_type = 0
query_cache_limit = 256K
query_cache_min_res_unit = 512
thread_stack = 192K
tmp_table_size = 96M
key_buffer_size = 8M
read_buffer_size = 2M
read_rnd_buffer_size = 16M
bulk_insert_buffer_size = 32M
#myisam
myisam_sort_buffer_size = 128M
#myisam_max_sort_file_size = 10G
myisam_max_sort_file_size = 100M
myisam_repair_threads = 1
#innodb
innodb_buffer_pool_size = 100M
innodb_buffer_pool_instances = 1
innodb_data_file_path = ibdata1:1G:autoextend
innodb_flush_log_at_trx_commit = 2
innodb_log_buffer_size = 64M
innodb_log_file_size = 500M
innodb_log_files_in_group = 3
innodb_max_dirty_pages_pct = 50
innodb_file_per_table = 1
innodb_rollback_on_timeout
innodb_status_file = 1
innodb_io_capacity = 2000
transaction_isolation = READ-COMMITTED
innodb_flush_method = O_DIRECT
端口3307,3308,3309的MySQL实例的配置文件和端口3306的配置文件相似，只需要替换端口即可
# cp my_3306.cnf my_3307.cnf
# cp my_3306.cnf my_3308.cnf
# cp my_3306.cnf my_3309.cnf
# sed -i 's/3306/3307/g' my_3307.cnf
# sed -i 's/3306/3308/g' my_3308.cnf
# sed -i 's/3306/3309/g' my_3309.cnf
# chown mysq.mysql /data/mysql/conf -R
2、初始化数据库
# cd /usr/local/mysql
# ./scripts/mysql_install_db --user=mysql --defaults-file=/data/mysql/conf/my_3306.cn --datadir=/data/mysql/mysql_3306/
# ./scripts/mysql_install_db --user=mysql --defaults-file=/data/mysql/conf/my_3307.cn --datadir=/data/mysql/mysql_3307/
# ./scripts/mysql_install_db --user=mysql --defaults-file=/data/mysql/conf/my_3308.cn --datadir=/data/mysql/mysql_3308/
# ./scripts/mysql_install_db --user=mysql --defaults-file=/data/mysql/conf/my_3309.cn --datadir=/data/mysql/mysql_3309/
3、启动数据库
# mysqld_safe --defaults-file=/data/mysql/conf/my_3306.cnf &
# mysqld_safe --defaults-file=/data/mysql/conf/my_3307.cnf &
# mysqld_safe --defaults-file=/data/mysql/conf/my_3308.cnf &
# mysqld_safe --defaults-file=/data/mysql/conf/my_3309.cnf &
观察MySQL进程
# ps -ef | grep mysqld
root 15873 12043 0 09:55 pts/0 00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --defaults-file=/data/mysql/conf/my_3306.cnf