Galera集群介绍
MariaDB集群是MariaDB同步多主机集群。它仅支持XtraDB/ InnoDB存储引擎。
主要功能
- 同步复制
- 真正的multi-master，即所有节点可以同时读写数据库
- 自动的节点成员控制，失效节点自动被清除
- 新节点加入数据自动复制
- 真正的并行复制，行级
- 用户可以直接连接集群，使用感受上与MySQL完全一致
优势
- 因为是多主，所以不存在Slavelag(延迟)
- 不存在丢失事务的情况
- 同时具有读和写的扩展能力
- 更小的客户端延迟
- 节点间数据是同步的,而Master/Slave模式是异步的,不同slave上的binlog可能是不同的
技术
Galera集群的复制功能基于Galeralibrary实现,为了让MySQL与Galera library通讯，特别针对MySQL开发了wsrep API。
Galera插件保证集群同步数据，保持数据的一致性，靠的就是可认证的复制，工作原理如下图：
当客户端发出一个commit的指令，在事务被提交之前，所有对数据库的更改都会被 write-set 收集起来,并且将 write-set 纪录的内容发送给其他节点。
write-set 将在每个节点进行认证测试，测试结果决定着节点是否应用write-set更改数据。
如果认证测试失败，节点将丢弃 write-set ；如果认证测试成功，则事务提交。
安装环境准备
准备三台服务器
操作系统版本： centos7
数据库版本：5.5.56-MariaDB
主节点：192.168.64.4
节点1：192.168.64.5
节点2：192.168.64.7
各个节点之间需要解析
[root@ken-node1 ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
:: localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.64.4 ken-node1
192.168.64.5 ken-node2
192.168.64.7 ken-node3
配置yum源
[mariadb]
name = MariaDB
baseurl = http://yum.mariadb.org/10.3.5/centos74-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=
enabled=
安装配置
第一步：在各个节点下载下面的软件包
[root@ken ~]# yum install -y MariaDB-server MariaDB-client galera -y
第二步: 初始化数据库
只需要在一个节点执行即可192.168.64.4
[root@ken ~]# systemctl restart mariadb
[root@ken ~]# mysql_secure_installation NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY! In order to log into MariaDB to secure it, we'll need the current
password for the root user. If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here. Enter current password for root (enter for none):
OK, successfully used password, moving on... Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation. Set root password? [Y/n] y
New password:
Re-enter new password:
Password updated successfully!
Reloading privilege tables..
... Success! By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them. This is intended only for testing, and to make the installation
go a bit smoother. You should remove them before moving into a
production environment. Remove anonymous users? [Y/n] y
... Success! Normally, root should only be allowed to connect from 'localhost'. This
ensures that someone cannot guess at the root password from the network. Disallow root login remotely? [Y/n] n
... skipping. By default, MariaDB comes with a database named 'test' that anyone can
access. This is also intended only for testing, and should be removed
before moving into a production environment. Remove test database and access to it? [Y/n] n
... skipping. Reloading the privilege tables will ensure that all changes made so far
will take effect immediately. Reload privilege tables now? [Y/n] y
... Success! Cleaning up... All done! If you've completed all of the above steps, your MariaDB
installation should now be secure.
Thanks for using MariaDB!
第三步：关闭数据库，修改/etc/my.cnf.d/server.cnf
在主配置节点配置如下
[root@ken ~]# systemctl stop mariadb
[root@ken ~]# vim /etc/my.cnf.d/server.cnf
...
[galera]
wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.64.4,192.168.64.5,192.168,64.7" #节点IP地址
wsrep_node_name= ken-node1 #主节点主机名
wsrep_node_address=192.168.64.4 #主节点IP
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=
wsrep_slave_threads=
innodb_flush_log_at_trx_commit=
innodb_buffer_pool_size=120M
wsrep_sst_method=rsync
wsrep_causal_reads=ON
第四步：将此文件复制到mariadb-2、mariadb-3，注意要把 wsrep_node_name 和 wsrep_node_address 改成相应节点的 hostname 和 ip。
第五步：启动集群
主节点192.168.64.4启动命令如下：
[root@ken-node1 ~]# galera_new_cluster
各个节点监听的端口
集群服务监听了4567和3306端口(每个节点都监听了4567和3306端口)
[root@ken-node1 ~]# ss -tnl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN *: *:*
LISTEN *: *:*
LISTEN 127.0.0.1: *:*
LISTEN ::: :::*
LISTEN ::: :::*
LISTEN ::: :::*
LISTEN ::: :::*
其他节点启动命令如下：
[root@ken-node2 ~]# systemctl restart mariadb
验证集群
在主节点执行如下操作
连接mariadb,查看是否启用galera插件
显示ON表示开启
MariaDB [(none)]> show status like "wsrep_ready";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wsrep_ready | ON |
+---------------+-------+
row in set (0.005 sec)
查看目前集群机器数
机器数为3个显示正确
MariaDB [(none)]> show status like "wsrep_cluster_size";
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | |
+--------------------+-------+
row in set (0.003 sec)
查看集群状态
MariaDB [(none)]> show status like "wsrep%";
+------------------------------+-------------------------------------------------------+
| Variable_name | Value |
+------------------------------+-------------------------------------------------------+
| wsrep_apply_oooe | 0.000000 |
| wsrep_apply_oool | 0.000000 |
| wsrep_apply_window | 0.000000 |
| wsrep_causal_reads | |
| wsrep_cert_deps_distance | 0.000000 |
| wsrep_cert_index_size | |
| wsrep_cert_interval | 0.000000 |
| wsrep_cluster_conf_id | |
| wsrep_cluster_size | |
| wsrep_cluster_state_uuid | 541248ce-56d0-11e9-b41b-3a9775d73ca7 |
| wsrep_cluster_status | Primary #主服务器 |
| wsrep_commit_oooe | 0.000000 |
| wsrep_commit_oool | 0.000000 |
| wsrep_commit_window | 0.000000 |
| wsrep_connected | ON #当前是否连接中 |
| wsrep_desync_count | |
| wsrep_evs_delayed | |
| wsrep_evs_evict_list | |
| wsrep_evs_repl_latency | //// |
| wsrep_evs_state | OPERATIONAL |
| wsrep_flow_control_paused | 0.000000 |
| wsrep_flow_control_paused_ns | |
| wsrep_flow_control_recv | |
| wsrep_flow_control_sent | |
| wsrep_gcomm_uuid | 540ee869-56d0-11e9-955e-9b7f30e437a6 |
| wsrep_incoming_addresses | 192.168.64.5:,192.168.64.4:,192.168.64.7: | #连接中的数据库
| wsrep_last_committed | |
| wsrep_local_bf_aborts | |
| wsrep_local_cached_downto | |
| wsrep_local_cert_failures | |
| wsrep_local_commits | |
| wsrep_local_index | |
| wsrep_local_recv_queue | |
| wsrep_local_recv_queue_avg | 0.100000 |
| wsrep_local_recv_queue_max | |
| wsrep_local_recv_queue_min | |
| wsrep_local_replays | |
| wsrep_local_send_queue | |
| wsrep_local_send_queue_avg | 0.000000 |
| wsrep_local_send_queue_max | |
| wsrep_local_send_queue_min | |
| wsrep_local_state | |
| wsrep_local_state_comment | Synced |
| wsrep_local_state_uuid | 541248ce-56d0-11e9-b41b-3a9775d73ca7 |
| wsrep_protocol_version | |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy <info@codership.com> |
| wsrep_provider_version | 25.3.(r3789) |
| wsrep_ready | ON |
| wsrep_received | |
| wsrep_received_bytes | |
| wsrep_repl_data_bytes | |
| wsrep_repl_keys | |
| wsrep_repl_keys_bytes | |
| wsrep_repl_other_bytes | |
| wsrep_replicated | |
| wsrep_replicated_bytes | |
| wsrep_thread_count | |
+------------------------------+-------------------------------------------------------+
rows in set (0.002 sec)
查看连接的主机
MariaDB [(none)]> show status like "wsrep_incoming_addresses";
+--------------------------+-------------------------------------------------------+
| Variable_name | Value |
+--------------------------+-------------------------------------------------------+
| wsrep_incoming_addresses | 192.168.64.5:,192.168.64.4:,192.168.64.7: |
+--------------------------+-------------------------------------------------------+
row in set (0.001 sec)
测试集群是否同步
在各个节点创建数据库，可以发现每个节点都可以同步
我在192.168.64.4创建ken数据库
[root@ken-node1 ~]# mysql -uroot -p
Enter password:
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is
Server version: 10.3.-MariaDB MariaDB Server Copyright (c) , , Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> create database ken;
Query OK, row affected (0.041 sec) MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| ken |
| ken1 |
| mysql |
| performance_schema |
| test |
+--------------------+
rows in set (0.001 sec)
在192.168.64.5节点上查看数据库
[root@ken-node2 ~]# mysql -uroot -p
Enter password:
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is
Server version: 10.3.-MariaDB MariaDB Server Copyright (c) , , Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| ken | #ken数据库已经同步过来
| mysql |
| performance_schema |
| test |
+--------------------+
rows in set (0.002 sec)
192.168.64.7节点上查看数据库
[root@ken-node3 ~]# mysql -uroot -p
Enter password:
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is
Server version: 10.3.-MariaDB MariaDB Server Copyright (c) , , Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| ken | #ken数据库已经同步 |
| mysql |
| performance_schema |
| test |
+--------------------+
rows in set (0.002 sec)