PXC是Percona XtraDB Cluster的缩写，是一种具有高可用性和高扩展性的MySQL开源集群。它集成了Percona Server和Percona XtraBackup，同时采用了Codership Galera库。

优点：
1.准同步复制
2.多个可同时读写节点，可实现写扩展，较分片方案更进一步
3.自动节点管理
4.数据严格一致
5.服务高可用

缺点：
1.只支持innodb引擎
2.所有表都要有主键
3.所有的写操作都将发生在所有节点上，存在写扩大问题
4.加入新节点，开销大。需要复制完整的数据。

部署准备工作

三个PXC节点分别配置防火墙

[root@pxc-linux-28 ~]# firewall-cmd --add-port=3306/tcp --permanent
[root@pxc-linux-28 ~]# firewall-cmd --add-port=4567/tcp --permanent
[root@pxc-linux-28 ~]# firewall-cmd --add-port=4568/tcp --permanent
[root@pxc-linux-28 ~]# firewall-cmd --add-port=4444/tcp --permanent
[root@pxc-linux-28 ~]# firewall-cmd --reload

安装相关yum源

rpm -Uvh https://www.percona.com/downloads/percona-release/redhat/latest/percona-release-0.1-4.noarch.rpm

安装pxc

yum install Percona-XtraDB-Cluster-57 -y

分别在三个节点创建数据存储目录

mkdir -p /data/local/percona-xtradb-cluster/data
chown -R mysql:mysql /data/local/percona-xtradb-cluster/data
mkdir -p /data/local/percona-xtradb-cluster/run
chown -R mysql:mysql /data/local/percona-xtradb-cluster/run
mkdir -p /data/logs/mysql
chown -R mysql:mysql /data/logs/mysql

修改/etc/my.cnf配置文件，其他两台节点需要修改server_id和wsrep_node_address

pxc-linux-28:

#cat /etc/my.cnf
[client]
port = 3306
socket = /data/local/percona-xtradb-cluster/run/mysql.sock
default-character-set = utf8mb4
[mysqld]
user =  mysql
innodb_buffer_pool_size = 1024M
character_set_server = utf8mb4
datadir = /data/local/percona-xtradb-cluster/data
port = 3306
server_id = 28
socket = /data/local/percona-xtradb-cluster/run/mysql.sock
pid-file = /data/local/percona-xtradb-cluster/run/mysql.pid
log-error = /data/logs/mysql/error.log
log_warnings = 2
slow_query_log_file = /data/logs/mysql/slow.log
long_query_time = 2
log_timestamps=SYSTEM
lower_case_table_names = 1
key_buffer_size = 1344M
event_scheduler=ON
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
wsrep_provider=/usr/lib64/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.253.28,192.168.253.29,192.168.253.30
binlog_format=ROW
pxc_strict_mode=PERMISSIVE
max_connect_errors=1000
max_allowed_packet = 1024M
default_storage_engine=InnoDB
#Innodb
innodb_flush_method = O_DIRECT
innodb_log_files_in_group = 5
innodb_lock_wait_timeout = 50
innodb_log_file_size = 1024M
innodb_flush_log_at_trx_commit = 1
innodb_file_per_table = 1
innodb_thread_concurrency = 8
innodb_buffer_pool_size = 5G
innodb_read_io_threads = 24
innodb_write_io_threads = 24
log_bin_trust_function_creators=1
innodb_autoinc_lock_mode=2
innodb_locks_unsafe_for_binlog=1
# CACHES AND LIMITS #
tmp_table_size = 32M
max_heap_table_size = 32M
max_connections = 1000
thread_cache_size = 50
open_files_limit = 65535
table_definition_cache = 4096
table_open_cache = 5000
#wsrep
wsrep_retry_autocommit=1
wsrep_auto_increment_control=1
wsrep_node_name = pxc-linux-28
wsrep_node_address=192.168.253.28
wsrep_sst_method=xtrabackup-v2
wsrep_cluster_name=test-pxc
wsrep_sst_auth="sync_rep:abc123"

pxc-linux-29:

[client]
port = 3306
socket = /data/local/percona-xtradb-cluster/run/mysql.sock
default-character-set = utf8mb4
[mysqld]
user =  mysql
innodb_buffer_pool_size = 1024M
character_set_server = utf8mb4
datadir = /data/local/percona-xtradb-cluster/data
port = 3306
server_id = 29
socket = /data/local/percona-xtradb-cluster/run/mysql.sock
pid-file = /data/local/percona-xtradb-cluster/run/mysql.pid
log-error = /data/logs/mysql/error.log
log_warnings = 2
slow_query_log_file = /data/logs/mysql/slow.log
long_query_time = 2
log_timestamps=SYSTEM
log_bin_trust_function_creators=1
lower_case_table_names=1
key_buffer_size = 1344M
event_scheduler=ON
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
wsrep_provider=/usr/lib64/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.253.28,192.168.253.29,192.168.253.30
binlog_format=ROW
pxc_strict_mode=PERMISSIVE
max_connect_errors=1000
max_allowed_packet = 1024M
default_storage_engine=InnoDB
#Innodb
innodb_flush_method = O_DIRECT
innodb_log_files_in_group = 5
innodb_lock_wait_timeout = 50
innodb_log_file_size = 1024M
innodb_flush_log_at_trx_commit = 1
innodb_file_per_table = 1
innodb_thread_concurrency = 8
innodb_buffer_pool_size = 5G
innodb_read_io_threads = 24
innodb_write_io_threads = 24
log_bin_trust_function_creators=1
innodb_autoinc_lock_mode=2
innodb_locks_unsafe_for_binlog=1
# CACHES AND LIMITS #
tmp_table_size = 32M
max_heap_table_size = 32M
max_connections = 1000
thread_cache_size = 50
open_files_limit = 65535
table_definition_cache = 4096
table_open_cache = 5000
#wsrep
wsrep_retry_autocommit=1
wsrep_auto_increment_control=1
wsrep_node_name =pxc-linux-29
wsrep_node_address=192.168.253.29
wsrep_sst_method=xtrabackup-v2
wsrep_cluster_name=test-pxc
wsrep_sst_auth="sync_rep:abc123"

pxc-linux-30:

[client]
port = 3306
socket = /data/local/percona-xtradb-cluster/run/mysql.sock
default-character-set = utf8mb4
[mysqld]
user =  mysql
innodb_buffer_pool_size = 1024M
character_set_server = utf8mb4
datadir = /data/local/percona-xtradb-cluster/data
port = 3306
server_id = 30
socket = /data/local/percona-xtradb-cluster/run/mysql.sock
pid-file = /data/local/percona-xtradb-cluster/run/mysql.pid
log-error = /data/logs/mysql/error.log
log_warnings = 2
slow_query_log_file = /data/logs/mysql/slow.log
long_query_time = 2
log_timestamps=SYSTEM
lower_case_table_names = 1
key_buffer_size = 1344M
event_scheduler=ON
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
wsrep_provider=/usr/lib64/libgalera_smm.so
wsrep_cluster_address=gcomm://192.168.253.28,192.168.253.29,192.168.253.30
binlog_format=ROW
pxc_strict_mode=PERMISSIVE
max_connect_errors=1000
max_allowed_packet = 1024M
default_storage_engine=InnoDB
#Innodb
innodb_flush_method = O_DIRECT
innodb_log_files_in_group = 5
innodb_lock_wait_timeout = 50
innodb_log_file_size = 1024M
innodb_flush_log_at_trx_commit = 1
innodb_file_per_table = 1
innodb_thread_concurrency = 8
innodb_buffer_pool_size = 5G
innodb_read_io_threads = 24
innodb_write_io_threads = 24
log_bin_trust_function_creators=1
innodb_autoinc_lock_mode=2
innodb_locks_unsafe_for_binlog=1
# CACHES AND LIMITS #
tmp_table_size = 32M
max_heap_table_size = 32M
max_connections = 1000
thread_cache_size = 50
open_files_limit = 65535
table_definition_cache = 4096
table_open_cache = 5000
#wsrep
wsrep_retry_autocommit=1
wsrep_auto_increment_control=1
wsrep_node_name = pxc-linux-30
wsrep_node_address=192.168.253.30
wsrep_sst_method=xtrabackup-v2
wsrep_cluster_name=test-pxc
wsrep_sst_auth="sync_rep:abc123"

pxc-linux-28启动

systemctl start mysql@bootstrape

备注：谨记，只要是启动集群的第一个Node（首次搭建集群或者集群全部关闭），都要用此命令

pxc-linux-29和pxc-linux-30启动

systemctl start mysql

备注：谨记，只要集群有一个Node启动，其余节点都是用此命令

修改密码
mysql5.7版本日志均在error.log 里面生成

grep "temporary password"  /data/logs/mysql/error.log

使用改密码登陆MySQL，修改成自己想要的密码

mysql> alter user 'root'@'localhost' idnetified by '123456';

在pxc-linux-28MySQL中创建SST同步用户

mysql> GRANT PROCESS,RELOAD,LOCK TABLES,REPLICATION CLIENT ON *.* TO 'sync_rep'@'192.168.%.%' IDENTIFIED BY 'abc123';
mysql> flush privileges;

State Snapshot Transfer 是可以让one node (donor) 通过数据拷贝升级至joining node (joiner)。
一个新节点加入至集群中，需要同步数据，那么SST可以传输数据，让新节点成为集群的一部分。
SST的三个有效方法：mysqldump, rsync andxtrabackup。不过多解释，目前最好用的是xtrabackup

查看集群状态

集群验证

[root@pxc-linux-28 ~]# mysql -uroot -p
mysql> show variables like 'version';
+---------------+--------------+
| Variable_name | Value |
+---------------+--------------+
| version | 5.7.19-17-57 |
+---------------+--------------+
1 row in set (0.00 sec)
mysql> create database pxcdb;
mysql> use pxcdb;
mysql> create table t1(id tinyint,ename varchar(20));
mysql> insert into t1 values(1,'Leshami');
在29上进行验证
[root@pxc-linux-29 ~]# mysql -uroot -p
mysql> show databases;
+--------------------+
| Database       |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| pxcdb |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> show variables like 'server_id';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id    | 29 |
+---------------+-------+
1 row in set (0.01 sec)
mysql> select * from pxcdb.t1;
+------+---------+
| id | ename |
+------+---------+
| 1 | Leshami |
+------+---------+
1 row in set (0.00 sec)
--查看集群状态
mysql> show status like '%wsrep_clust%';
+--------------------------+--------------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------------+
| wsrep_cluster_conf_id | 13 |
| wsrep_cluster_size | 3 |
| wsrep_cluster_state_uuid | aeb87793-ebb2-11e7-b33e-eeaf4988bbe4 |
| wsrep_cluster_status | Primary |
+--------------------------+--------------------------------------+
4 rows in set (0.00 sec)
mysql> show status like 'wsrep_connected';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| wsrep_connected | ON |
+-----------------+-------+
1 row in set (0.00 sec)

openssl版本过低导致的错误

2017-12-28T09:23:19.605353Z 0 [ERROR] WSREP: wsrep_load(): dlopen(): /usr/lib64/galera3/libgalera_smm.so:
symbol SSL_COMP_free_compression_methods, version libssl.so.10 not defined in file libssl.so.10 with link time reference
2017-12-28T09:23:19.605379Z 0 [ERROR] WSREP: Failed to load wsrep_provider (/usr/lib64/galera3/libgalera_smm.so).Error: Invalid argument (code: 22). Reverting to no provider.
2017-12-28T09:23:19.605386Z 0 [Note] WSREP: Setting wsrep_ready to false
[root@pxc-linux-29 ~]# rpm -qa|grep openssl
openssl-1.0.1e-42.el7.9.x86_64
openssl-libs-1.0.1e-42.el7.9.x86_64
[root@pxc-linux-29 ~]# yum update openssl -y

需要升级openssl，建议全部升级后再启动集群，这问题在CentOS 7.4.1708不存在即openssl版本较新

Haproxy负载均衡

Haproxy是一个反向代理负载均衡解决方案，支持4层和7层模式，提供后端服务器健康检查，非常稳定。淘宝前期也使用Haproxy作为CDN系统负载均衡器。

安装haproxy

yum -y install haproxy

简单配置文件：

cat /etc/haproxy/haproxy.cfg
#---------------------------------------------------------------------
# Example configuration for a possible web application.  See the
# full configuration options online.
#
#   http://haproxy.1wt.eu/download/1.4/doc/configuration.txt
#
#---------------------------------------------------------------------
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global# to have these messages end up in /var/log/haproxy.log you will# need to:## 1) configure syslog to accept network log events.  This is done#    by adding the '-r' option to the SYSLOGD_OPTIONS in#    /etc/sysconfig/syslog## 2) configure local2 events to go to the /var/log/haproxy.log#   file. A line like the following can be added to#   /etc/sysconfig/syslog##    local2.*                       /var/log/haproxy.log#log         127.0.0.1 local2chroot      /var/lib/haproxypidfile     /var/run/haproxy.pidmaxconn     4000user        haproxygroup       haproxydaemon# turn on stats unix socketstats socket /var/lib/haproxy/stats
#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaultsmode                    httplog                     globaloption                  httplogoption                  dontlognulloption http-server-closeoption forwardfor       except 127.0.0.0/8option                  redispatchretries                 3timeout http-request    10stimeout queue           1mtimeout connect         10stimeout client          1mtimeout server          1mtimeout http-keep-alive 10stimeout check           10smaxconn                 3000
#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend pxc-frontbind *:3306mode tcpdefault_backend pxc-back
frontend statas-frontbind *:8088mode httpdefault_backend stats-back
#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend pxc-backmode tcpbalance leastconnoption httpchkserver pxc-linux-28 192.168.253.28:3306  check port 9200 inter 12000 rise 3 fall 3server pxc-linux-29 192.168.253.29:3306  check port 9200 inter 12000 rise 3 fall 3server pxc-linux-30 192.168.253.30:3306  check port 9200 inter 12000 rise 3 fall 3
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend stats-backmode httpbalance roundrobinstats uri /haproxy/statsstats auth pxcstats:xxwzopop

在cluster的MySQL上创建用户
(一个节点创建，会被复制到其它节点)
监控用帐号：

 grant usage on *.* to 'pxc-monitor'@'%' identified by 'testpxc';

服务测试帐号：

  grant all privileges on *.* to 'zxw'@'%' identified by 'xxwzopop';

更改用户名和密码（三个节点都得修改）

#vim /usr/bin/clustercheck
MYSQL_USERNAME="pxc-monitor"
MYSQL_PASSWORD="testpxc"

测试

[root@pxc-linux-28 ~]# clustercheck
HTTP/1.1 200 OK
Content-Type: text/plain
Connection: close
Content-Length: 40
Percona XtraDB Cluster Node is synced.

更改/etc/services添加mysqlchk的端口号：

mysqlchk  9200/tcp  #mysqlchk

配置xinetd
vi /etc/xinetd.d/mysqlchk
该文件保持默认即可

测试

#for i in `seq 1 1000`;do mysql -h 192.168.253.31 -P3306 -upxc -pabc123 -e "select @@hostname;";done
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------+
| @@hostname   |
+--------------+
| pxc-linux-30 |
+--------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------+
| @@hostname   |
+--------------+
| pxc-linux-28 |
+--------------+
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------+
| @@hostname   |
+--------------+
| pxc-linux-29 |
+--------------+

可以看到负载了

查看haproxy状态

http://192.168.253.31:8088/haproxy/stats

帐号密码是：pxcstats:xxwzopop

/etc/haproxy/haproxy.cfg 指定的。

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