转载自：
特色
MySQL/Galera 是一种
多主同步集群，但只限于使用 MySQL/
InnoDB 引擎，并具有下面特点
同步复制
多个主服务器的拓扑结构
可以在任意节点上进行读写
自动控制成员，
自动删除故障节点
自动加入节点
真正给予行级别的并发复制
调度客户连接
优势
参考下面基于 DBMS 集群的解决方法
不存在从服务器角色
不存在事务丢失
读写操作可根据需要进行随意扩展
更少的闩锁操作
知识点
MySQL/Galera 集群使用 Galera 库执行复制，对应 Galera 复制接口，我们需要MySQL 服务器支持 wsrep API 接口
是否可以使用 MySQL 而不使用 mariadb?
不可以，因为 mysql 中没有支持 wsrep_ 数据复制的参数，当然代码级别上也具有很大差别
工作原理
mariadb 可以看做是常见的数据库，负责连接应用(web, API 等）
单纯的 mariadb 无法实现多个主服务器数据同步
多台数据库中数据同步由 wsrep 接口实现
最终目标，实现多个 MySQL 同时读写
wsrep API
wsrep API 是一种数据库插件接口，比较类似一种应用程序，主要针对写复制
该程序主要用于定义应用程序如何调用复制库实现回写
wsrep API 由支持该库的应用程序动态装载
全局事务ID(GTID)
wsrep API 描述下面复制模型，一个应用程序，如数据库当前的一个对象，当前被客户端修改，对象改变导致事务产生一系列的原子性改变，
在集群中所有的节点都具备相同的对象，并由同步复制应用到各自节点，按照相同的顺序产生相同变化从而实现数据同步
到最后，wsrep API 将会分配一个全局事务ID 该 ID 具有下面功能
标识对象的改变
标识对象自身 ID 最后状态（正常情况下，
ID 是连续不中断的）
GTID 包含
一个 UUID 作为对象标识及经历改变的序号，序号会发生连续的改变
GTID 允许比较应用程序状态，建立对象改变的顺序，决定对象的变化是否需要更新 GTID
通常 GTID 会被记录成下面格式
45eec521-2f34-11e0-0800-2a36050b826b:94530586304
言归正传，我们需要编译 mariadb-mysql 及 galera 插件
galera/mysql 编译步骤
yum install -y cmake
tar xf mariadb-galera-5.5.33a.tar.gz
cd mariadb-5.5.33a/
cmake -LAH
参考 CMakeCache.txt 文件中的配置信息
cmake -DINSTALL_MYSQLDATADIR:STRING=/mdb -DINSTALL_UNIX_ADDRDIR:STRING=/var/run/mysqld/mysql5.socketmakemake install
默认情况下， mariadb 安装在 /usr/local/mysql
galera 编译
添加yum源
baseurl=
epel//6Server/x86_64/
添加下面软件包
yum erase -y mysql.x86_64 mysql-devel.x86_64 mysql-libs.x86_64 yum install -y boost-devel.x86_64 libodb-boost-devel.x86_64 bzr scons
解压 galera-23.2.7-src.tar.gz 并进行编译
cd /usr/srctar xf galera-23.2.7-src.tar.gzcd galera-23.2.7-srcscons
编译后生成 libgalera_smm.so
复制编译好的库至下面位置 /usr/local/galera/lib/
libgalera_smm.so
mkdir /usr/local/galera/lib -pcp /usr/src/galera-23.2.7-src/libgalera_smm.so /usr/local/galera/lib/libgalera_smm.so
复制 启动脚本 /usr/src/galera-23.2.7-src/scripts/mysql/mysql-galera 到 /usr/local
cp /usr/src/galera-23.2.7-src/scripts/mysql/mysql-galera /usr/local
创建 /usr/local/mysql/etc/my.cnf
[mysqld]basedir=/usr/local/mysqlbig-tablesbind-address=0.0.0.0
character-set-server=utf8
datadir=/mdb
log-error=/var/log/mysqld/
mysql5-error.logsocket=/var/run/mysqld/
mysql5.socketpid-file=/var/run/mysqld/
mysql5.pidport=3306
user=mysql
binlog_format = ROW
binlog_cache_size = 1M
character_set_server = utf8
collation_server = utf8_general_ci
default-storage-engine = InnoDB
expire_logs_days = 10
innodb_buffer_pool_size = 300M
innodb_thread_concurrency = 16
innodb_log_buffer_size = 8M
innodb_doublewrite = 1
innodb_file_per_table = 1
innodb_flush_log_at_trx_commit = 2
server-id = 1
max_connections = 1000
net_buffer_length = 8K
open-files-limit = 65535
wsrep_cluster_address = 'gcomm://192.168.200.163,192.168.200.171,172.18.8.49，172.18.8.50
'wsrep_provider = /usr/local/galera/lib/libgalera_smm.so
wsrep_retry_autocommit = 0
wsrep_sst_method = rsync
wsrep_provider_options="gcache.size=256m; gcache.page_size=256m
"wsrep_slave_threads=16wsrep_cluster_name='my_cluster'
wsrep_node_name='db5'
wsrep_sst_auth=tt:tt123maridb
启动测试
初始化数据库
mkdir /mdbcd /usr/local/mysql
./scripts/install_mysql_db --datadir=/mdb
启动脚本 /etc/rc.d/init.d/mysql5 确保文件可执行权限
#!/bin/sh# chkconfig: 2345 64 36# description: A very fast and reliable SQL database engine.
basedir=/usr/local/mysql datadir=/mdb
# Default value, in seconds, afterwhich the script should timeout waiting # for server start. # Value here is overriden by value in my.cnf. # 0 means don't wait at all # Negative numbers mean to wait indefinitely service_startup_timeout=900 startup_sleep=1
# Lock directory for RedHat / SuSE. lockdir='/var/lock/subsys' lock_file_path="$lockdir/mysql"
# The following variables are only set for letting mysql.server find things.
# Set some defaults mysqld_pid_file_path=/var/run/mysqld/mysql5.pid if test -z "$basedir" then basedir=/usr/local/mysql bindir=/usr/local/mysql/bin if test -z "$datadir" then datadir=/usr/local/mysql/data fi sbindir=/usr/local/mysql/bin libexecdir=/usr/local/mysql/bin
else bindir="$basedir/bin" if test -z "$datadir" then datadir="$basedir/data" fi sbindir="$basedir/sbin" if test -f "$basedir/bin/mysqld" then libexecdir="$basedir/bin" else libexecdir="$basedir/libexec" fi fi
# datadir_set is used to determine if datadir was set (and so should be # *not* set inside of the --basedir= handler.) datadir_set=
# # Use LSB init script functions for printing messages, if possible # lsb_functions="/lib/lsb/init-functions" if test -f $lsb_functions ; then . $lsb_functions else log_success_msg() { echo " SUCCESS! $@" } log_failure_msg() { echo " ERROR! $@" } fi
PATH="/sbin:/usr/sbin:/bin:/usr/bin:$basedir/bin"
export PATH
mode=$1 # start or stop
[ $# -ge 1 ] && shift
other_args="$*" # uncommon, but needed when called from an RPM upgrade action # Expected: "--skip-networking --skip-grant-tables" # They are not checked here, intentionally, as it is the resposibility # of the "spec" file author to give correct arguments only.
case `echo "testing/c"`,`echo -n testing` in *c*,-n*) echo_n= echo_c= ;; *c*,*) echo_n=-n echo_c= ;; *) echo_n= echo_c='/c' ;; esac
parse_server_arguments() { for arg do case "$arg" in --basedir=*) basedir=`echo "$arg" | sed -e 's/^[^=]*=//'` bindir="$basedir/bin" if test -z "$datadir_set"; then datadir="$basedir/data" fi sbindir="$basedir/sbin" if test -f "$basedir/bin/mysqld" then libexecdir="$basedir/bin" else libexecdir="$basedir/libexec" fi libexecdir="$basedir/libexec" ;; --datadir=*) datadir=`echo "$arg" | sed -e 's/^[^=]*=//'` datadir_set=1
;; --pid-file=*) mysqld_pid_file_path=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; --service-startup-timeout=*) service_startup_timeout=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; esac done }
wait_for_pid () { verb="$1" # created | removed pid="$2" # process ID of the program operating on the pid-file pid_file_path="$3" # path to the PID file.
sst_progress_file=$datadir/sst_in_progress i=0 avoid_race_condition="by checking again"
while test $i -ne $service_startup_timeout ; do
case "$verb" in 'created') # wait for a PID-file to pop into existence. test -s "$pid_file_path" && i='' && break ;; 'removed') # wait for this PID-file to disappear test ! -s "$pid_file_path" && i='' && break ;; *) echo "wait_for_pid () usage: wait_for_pid created|removed pid pid_file_path" exit 1 ;; esac
# if server isn't running, then pid-file will never be updated if test -n "$pid"; then if kill -0 "$pid" 2>/dev/null; then : # the server still runs
else # The server may have exited between the last pid-file check and now. if test -n "$avoid_race_condition"; then avoid_race_condition="" continue # Check again. fi
# there's nothing that will affect the file. log_failure_msg "The server quit without updating PID file ($pid_file_path)." return 1 # not waiting any more. fi fi
if test -e $sst_progress_file && [ $startup_sleep -ne 100 ];then echo $echo_n "SST in progress, setting sleep higher" startup_sleep=100 fi
echo $echo_n ".$echo_c" i=`expr $i + 1` sleep $startup_sleep
done
if test -z "$i" ; then log_success_msg return 0 else log_failure_msg return 1 fi }
# Get arguments from the my.cnf file, # the only group, which is read from now on is [mysqld] if test -x ./bin/my_print_defaults then
print_defaults="./bin/my_print_defaults" elif test -x $bindir/my_print_defaults then print_defaults="$bindir/my_print_defaults" elif test -x $bindir/mysql_print_defaults then print_defaults="$bindir/mysql_print_defaults" else # Try to find basedir in /etc/my.cnf conf=/usr/local/mysql/etc/my.cnf print_defaults= if test -r $conf then subpat='^[^=]*basedir[^=]*=/(.*/)$' dirs=`sed -e "/$subpat/!d" -e 's///1/' $conf` for d in $dirs do d=`echo $d | sed -e 's/[ ]//g'` if test -x "$d/bin/my_print_defaults" then print_defaults="$d/bin/my_print_defaults" break fi if test -x "$d/bin/mysql_print_defaults" then print_defaults="$d/bin/mysql_print_defaults" break fi done fi
# Hope it's in the PATH ... but I doubt it test -z "$print_defaults" && print_defaults="my_print_defaults" fi
# # Read defaults file from 'basedir'. If there is no defaults file there
# check if it's in the old (depricated) place (datadir) and read it from there #
extra_args="" if test -r "$basedir/my.cnf" then extra_args="-e $basedir/my.cnf" else if test -r "$datadir/my.cnf" then extra_args="-e $datadir/my.cnf" fi fi
parse_server_arguments `$print_defaults $extra_args mysqld server mysql_server mysql.server`
# # Set pid file if not given # if test -z "$mysqld_pid_file_path" then mysqld_pid_file_path=$datadir/`hostname`.pid else case "$mysqld_pid_file_path" in /* ) ;; * ) mysqld_pid_file_path="$datadir/$mysqld_pid_file_path" ;; esac fi
case "$mode" in 'start') # Start daemon
# Safeguard (relative paths, core dumps..) cd $basedir
echo $echo_n "Starting MySQL"
if test -x $bindir/mysqld_safe then # Give extra arguments to mysqld with the my.cnf file. This script # may be overwritten at next upgrade. $bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 & wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?
# Make lock for RedHat / SuSE if test -w "$lockdir" then touch "$lock_file_path" fi
exit $return_value else log_failure_msg "Couldn't find MySQL server ($bindir/mysqld_safe)" fi ;;
'stop') # Stop daemon. We use a signal here to avoid having to know the # root password.
if test -s "$mysqld_pid_file_path" then mysqld_pid=`cat "$mysqld_pid_file_path"`
if (kill -0 $mysqld_pid 2>/dev/null) then echo $echo_n "Shutting down MySQL" kill $mysqld_pid # mysqld should remove the pid file when it exits, so wait for it. wait_for_pid removed "$mysqld_pid" "$mysqld_pid_file_path"; return_value=$? else log_failure_msg "MySQL server process #$mysqld_pid is not running!" rm "$mysqld_pid_file_path" fi
# Delete lock for RedHat / SuSE if test -f "$lock_file_path" then rm -f "$lock_file_path" fi exit $return_value else log_failure_msg "MySQL server PID file could not be found!" fi ;;
'restart') # Stop the service and regardless of whether it was # running or not, start it again. if $0 stop $other_args; then $0 start $other_args else log_failure_msg "Failed to stop running server, so refusing to try to start." exit 1 fi ;;
'reload'|'force-reload') if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path" kill -HUP $mysqld_pid && log_success_msg "Reloading service MySQL" touch "$mysqld_pid_file_path" else log_failure_msg "MySQL PID file could not be found!" exit 1 fi ;; 'status') # First, check to see if pid file exists if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path"
if kill -0 $mysqld_pid 2>/dev/null ; then log_success_msg "MySQL running ($mysqld_pid)" exit 0 else log_failure_msg "MySQL is not running, but PID file exists" exit 1 fi else # Try to find appropriate mysqld process mysqld_pid=`pidof $libexecdir/mysqld`
# test if multiple pids exist pid_count=`echo $mysqld_pid | wc -w` if test $pid_count -gt 1 ; then log_failure_msg "Multiple MySQL running but PID file could not be found ($mysqld_pid)" exit 5 elif test -z $mysqld_pid ; then if test -f "$lock_file_path" ; then log_failure_msg "MySQL is not running, but lock file ($lock_file_path) exists" exit 2 fi log_failure_msg "MySQL is not running" exit 3 else log_failure_msg "MySQL is running but PID file could not be found" exit 4 fi fi ;; 'configtest') # Safeguard (relative paths, core dumps..) cd $basedir echo $echo_n "Testing MySQL configuration syntax" daemon=$bindir/mysqld if test -x $libexecdir/mysqld then daemon=$libexecdir/mysqld elif test -x $sbindir/mysqld then daemon=$sbindir/mysqld elif test -x `which mysqld` then daemon=`which mysqld` else log_failure_msg "Unable to locate the mysqld binary!" exit 1 fi help_out=`$daemon --help 2>&1`; r=$? if test "$r" != 0 ; then log_failure_msg "$help_out" log_failure_msg "There are syntax errors in the server configuration. Please fix them!" else log_success_msg "Syntax OK" fi exit $r ;; 'bootstrap') # Bootstrap the cluster, start the first node # that initiate the cluster echo $echo_n "Bootstrapping the cluster" $0 start $other_args --wsrep-new-cluster ;; *) # usage basename=`basename "$0"` echo "Usage: $basename {start|stop|restart|reload|force-reload|status|configtest|bootstrap} [ MySQL server options ]" exit 1 ;; esac
exit 0
启动每一台数据库
service mysql5 start
在每台数据库中建立下面用户， 用于 ssl 认证
GRANT USAGE ON *.* to tt@'%' IDENTIFIED BY 'tt123';
GRANT ALL PRIVILEGES on *.* to tt@'%';
GRANT USAGE ON *.* to tt@'localhost' IDENTIFIED BY 'tt123';
GRANT ALL PRIVILEGES on *.* to tt@'localhost';
flush privileges;
关闭所有数据库
service mysql5 stop
创建并加入集群
集群中第一个节点启动 (192.168.200.163)
创建软链接，并启动集群，集群启动过程中会自动启动 mariadb
ln -s /usr/local/mysql/bin/ /usr/local/mysql/sbincd /usr/local/./mysql-galera -g gcomm:// start
测试是否成功启动方法, 查询是否会自动启动 4567 端口
[root@db2 local]# netstat -ntl
Active Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address Statetcp
0 0 0.0.0.0:3306 0.0.0.0:* LISTENtcp 0 0 0.0.0.0:22 0.0.0.0:* LISTENtcp 0 0 0.0.0.0:4567 0.0.0.0:* LISTEN
登录 mysql 之后，查询当前是否启用 galery 插件
MariaDB [(none)]> show status like 'wsrep_ready';
+---------------+-------+| Variable_name | Value |+---------------+-------+|
wsrep_ready | ON |+---------------+-------+
1 row in set (0.00 sec)
注，on 为已经启动插件状态
关闭方法
cd /usr/local./mysql-galera stop
其他节点加入集群方法
第一台 (192.168.200.163) 节点已经启动成功
第二台 (192.168.200.171) 需要加入集群
cd /usr/local/
./mysql-galera -g
gcomm://192.168.200.163 start
可按上述方法进行集群启动测试, 也可以参照下面方法, 观察集群地址是否增加两个服务器地址
MariaDB [(none)]> show status like 'wsrep_incoming_addresses';
+--------------------------+-------------------------------------------+| Variable_name | Value |+--------------------------+-------------------------------------------+| wsrep_incoming_addresses | 192.168.200.171:3306,192.168.200.163:3306 |+--------------------------+-------------------------------------------+1 row in set (0.00 sec)
第三台 (172.18.8.49) 需要加入集群
cd /usr/local/
./mysql-galera -g gcomm://192.168.200.163,192.168.200.171 start
第四台 (172.18.8.50) 需要加入集群
cd /usr/local/./mysql-galera -g gcomm://192.168.200.163,192.168.200.171,172.18.8.49 start
注: 每次集群启动， 将会启用数据同步机制，令每个集群中的数据同步
假如，集群工作期间，节点 3(172.18.8.49) 脱离集群，重启，发生故障而脱机期间
节点1,2,4 仍可继续工作当节点3 重新在线时，加入集群前，将会自动进行数据同步
重新在线方法与上文中加入节点方法一致
常见 wsrep 参数注释
MariaDB [terry]> show status like 'wsrep%';
+----------------------------+--------------------------------------+| Variable_name | Value |+----------------------------+--------------------------------------+| wsrep_local_state_uuid | bb5b9e17-66c8-11e3-86ba-96854521d205 | uuid 集群唯一标记| wsrep_protocol_version | 4 || wsrep_last_committed | 16 | sql 提交记录| wsrep_replicated | 4 | 随着复制发出的次数| wsrep_replicated_bytes | 692 | 数据复制发出的字节数| wsrep_received | 18 | 数据复制接收次数| wsrep_received_bytes | 3070 | 数据复制接收的字节数| wsrep_local_commits | 4 | 本地执行的 sql| wsrep_local_cert_failures | 0 | 本地失败事务| wsrep_local_bf_aborts | 0 |从执行事务过程被本地中断| wsrep_local_replays | 0 || wsrep_local_send_queue | 0 | 本地发出的队列| wsrep_local_send_queue_avg | 0.142857 | 队列平均时间间隔| wsrep_local_recv_queue | 0 | 本地接收队列| wsrep_local_recv_queue_avg | 0.000000 | 本地接收时间间隔| wsrep_flow_control_paused | 0.000000 || wsrep_flow_control_sent | 0 || wsrep_flow_control_recv | 0 || wsrep_cert_deps_distance | 0.000000 | 并发数量 | wsrep_apply_oooe | 0.000000 || wsrep_apply_oool | 0.000000 || wsrep_apply_window | 1.000000 || wsrep_commit_oooe | 0.000000 || wsrep_commit_oool | 0.000000 || wsrep_commit_window | 1.000000 || wsrep_local_state | 4 || wsrep_local_state_comment | Synced || wsrep_cert_index_size | 0 || wsrep_causal_reads | 0 || wsrep_incoming_addresses | 172.18.8.50:3306,172.18.8.49:3306 | 连接中的数据库| wsrep_cluster_conf_id | 18 || wsrep_cluster_size | 2 | 集群成员个数| wsrep_cluster_state_uuid | bb5b9e17-66c8-11e3-86ba-96854521d205 | 集群 ID| wsrep_cluster_status | Primary | 主服务器| wsrep_connected | ON | 当前是否连接中| wsrep_local_index | 1 || wsrep_provider_name | Galera || wsrep_provider_vendor | Codership Oy
|| wsrep_provider_version | 2.7(rXXXX) || wsrep_ready | ON |
插件是否应用中+----------------------------+--------------------------------------+40 rows in set (0.05 sec)
时间关系，还没有时间进行压力测试，也没有比对 galera 与 Percona XtraDB Cluster 集群之间区别
另外，如使用 rpm 则十分方便，网路很多教程， 不详细描述
