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
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
更少的闩操作
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
http://www.codership.com/products/mysql-write-set-replication-project
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
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 由支持改库的应用程序动态装载
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，并由同步复制应用都各自节点，按照相同的顺序产生相同变化从而实现数据同步
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 会卑记录成下面格式
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
https://downloads.mariadb.org/interstitial/mariadb-galera-5.5.33a/kvm-tarbake-jaunty-x86/mariadb-galera-5.5.33a.tar.gz/from/http://mirrors.scie.in/mariadb
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.socketmake
make install
galera 编译
https://launchpad.net/galera/2.x/23.2.7/+download/galera-23.2.7-src.tar.gz
添加数据源
baseurl=http://mirror.neu.edu.cn/fedora/epel//6Server/x86_64/添加下面软件包
yum erase -y mysql.x86_64 mysql-devel.x86_64 mysql-libs.x86_64yum install -y boost-devel.x86_64 libodb-boost-devel.x86_64 bzr scons
tar xf galera-23.2.7-src.tar.gz
cd galera-23.2.7-src
scons
编译后能生成 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
basedir=/usr/local/mysql
big-tables
bind-address=0.0.0.0
character-set-server=utf8
datadir=/mdb
log-error=/var/log/mysqld/mysql5-error.log
socket=/var/run/mysqld/mysql5.socket
pid-file=/var/run/mysqld/mysql5.pid
port=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=16
wsrep_cluster_name='my_cluster'
wsrep_node_name='db5'
wsrep_sst_auth=tt:tt123
初始化数据库
mkdir /mdbcd /usr/local/mysql
./scripts/install_mysql_db --datadir=/mdb
# 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 "testingc"`,`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
GRANT ALL PRIVILEGES on *.* to tt@'%';
GRANT USAGE ON *.* to tt@'localhost' IDENTIFIED BY 'tt123';
GRANT ALL PRIVILEGES on *.* to tt@'localhost';
flush privileges;
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
cd /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 -ntlActive Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 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 galera 插件
MariaDB [(none)]> show status like 'wsrep_ready';+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_ready | ON |
+---------------+-------+
1 row in set (0.00 sec)
./mysql-galera stop
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
./mysql-galera -g gcomm://192.168.200.163 start
+--------------------------+-------------------------------------------+
| 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
./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
另外，假如觉得要定义所有的服务器地址麻烦，可以加入集群时候只定义其中一台的地址，如 gcomm://192.168.200.163 集群也能够自动在加入后添加其他集群 url地址
+----------------------------+--------------------------------------+
| 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 <info@codership.com> |
| wsrep_provider_version | 2.7(rXXXX) |
| wsrep_ready | ON | 插件是否应用中
+----------------------------+--------------------------------------+
40 rows in set (0.05 sec)
另，如使用 rpm 则十分方便，网路很多教程， 不详细描述
auto_increment
当更多的 MariaDB 加入到集群之后，集群中的数据库会自动进行协调，并且自动定义偏移量， 这个比较人性化，自动化，如下描述
db1:
MariaDB [(none)]> show variables like 'auto_increment%';+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 3 |
+--------------------------+-------+
2 rows in set (0.00 sec)
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 4 |
+------------------------
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 2 |
+--------------------------+-------+
2 rows in set (0.00 sec)
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 4 |
| auto_increment_offset | 1 |
+--------------------------+-------+
2 rows in set (0.00 sec)
模拟测试1
创建测试表
MariaDB [(none)]> desc terry.t2;+-------+-------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+-------------------+-----------------------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(20) | YES | | NULL | |
| time | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------+-------------+------+-----+-------------------+-----------------------------+
3 rows in set (0.00 sec)
在每台电脑中创建对应的数据插入脚本 (太大量的并发插入会导致服务器不断脱离集群，最终只剩下一次，因此减少数据插入量)
[root@db6 mdb]# cat /tmp/in.sh#!/bin/bash
for (( a=1 ; a<=1000 ; a++ ))
do
name="db6.$a"
mysql -u terry -p123 -e "insert into terry.t2 (name, time) values ("$name", now())"
done
插入过程中, 会出现锁，有一个数据库集群会自动脱离集群 >_<"
MySQL thread id 16, OS thread handle 0x7f2f2019a700, query id 4666 applied write set 183192TABLE LOCK table `terry`.`t2` trx id 2D3EF lock mode IX
---TRANSACTION 2D3EE, ACTIVE 0 sec
mysql tables in use 1, locked 1
1 lock struct(s), heap size 376, 0 row lock(s), undo log entries 1
MySQL thread id 633, OS thread handle 0x7f2f20076700, query id 4664 localhost terry query end
insert into terry.t2 (name, time) values ("db5.603", now())
TABLE LOCK table `terry`.`t2` trx id 2D3EE lock mode IX
---TRANSACTION 2D3ED, ACTIVE (PREPARED) 0 sec preparing
1 lock struct(s), heap size 376, 0 row lock(s), undo log entries 1
MySQL thread id 3, OS thread handle 0x7f2f3be4e700, query id 4662 committing 183190
参考其他三台 时间返回值
db1 (使用 13 秒)
db2 (使用 24秒)
db3(使用14秒)
db4(写入 35 条数据后 crash)
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