Mysql集群
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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
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
http://www.codership.com/products/mysql-write-set-replication-project
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 由支持改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
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.socketmakemake install
默认情况下， mariadb 安装在 /usr/local/mysql
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_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
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=0.0.0.0character-set-server=utf8datadir=/mdblog-error=/var/log/mysqld/mysql5-error.logsocket=/var/run/mysqld/mysql5.socketpid-file=/var/run/mysqld/mysql5.pidport=3306user=mysqlbinlog_format = ROWbinlog_cache_size = 1Mcharacter_set_server = utf8collation_server = utf8_general_cidefault-storage-engine = InnoDBexpire_logs_days = 10innodb_buffer_pool_size = 300Minnodb_thread_concurrency = 16innodb_log_buffer_size = 8Minnodb_doublewrite = 1innodb_file_per_table = 1innodb_flush_log_at_trx_commit = 2server-id = 1max_connections = 1000net_buffer_length = 8Kopen-files-limit = 65535wsrep_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.sowsrep_retry_autocommit = 0wsrep_sst_method = rsyncwsrep_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
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 sst 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 -ntlActive 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 <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)
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，如使用 rpm 则十分方便，网路很多教程， 不详细描述
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