一、Galera Cluster
Galera是一個MySQL(也支持MariaDB，Percona)的同步多主集羣軟件，Galera集羣的複製功能基於Galeralibrary實現,爲了讓MySQL與Galera library通訊，特別針對MySQL開發了wsrep API。
二、Galera Cluster的功能和優勢
功能： multi-master，即所有節點可以同時讀寫數據庫 自動的節點成員控制，失效節點自動被清除 新節點加入數據自動複製 並行複製，行級 |
優勢: 因爲是multi-master，所以不存在延遲；更小的客戶端延遲 同時具有讀和寫的擴展能力 節點間數據是同步的,而Master/Slave模式是異步的,不同slave上的binlog可能是不同的 |
三、實現Galera Cluster過程；簡單實現
1、準備工作
①測試環境： CentOS 7 ；
| node1 | 172.16.116.231 |
| node2 | 172.16.116.232 |
| node3 | 172.16.116.233 |
//同步各節點的時間 # ntpdate ntp.sjtu.edu.cn //主機互信 # vim /etc/hosts 172.16.116.231 node1 172.16.116.232 node2 172.16.116.233 node3 //名稱服務器 # vim /etc/resolv.conf nameserver 172.16.0.1
②安裝包選擇
galera-25.3.9-1.rhel7.el7.centos.x86_64.rpm MariaDB-5.5.46-centos7-x86_64-client.rpm MariaDB-5.5.46-centos7-x86_64-common.rpm MariaDB-Galera-5.5.46-centos7-x86_64-server.rpm
2、各節點安裝上述的軟件包
# yum install -y *rpm //安裝完成，配置node1 [root@node1 ~]# vim /etc/my.cnf.d/server.cnf [galera] # Mandatory settings wsrep_provider=/usr/lib64/galera/libgalera_smm.so wsrep_cluster_address=gcomm://172.16.116.231,172.16.116.232,172.16.116.233 //定義節點 wsrep_cluster_name=Mycluster //集羣名稱 binlog_format=row //二進制格式爲row default_storage_engine=InnoDB //默認存儲引擎爲innodb innodb_autoinc_lock_mode=2 bind-address=0.0.0.0 //綁定ip //啓動服務；要加上--wsrep-new-cluster 這個參數，否則爲報錯error [root@node1 ~]# /etc/init.d/mysql start --wsrep-new-cluster Starting MySQL.... SUCCESS!
3、啓動後查看的結果
########將/etc/my.cnf.d/server.cnf遠程複製給node2，node3，啓動node2，node3 [root@node2 ~]# /etc/init.d/mysql start Starting MySQL......SST in progress, setting sleep higher. SUCCESS! [root@node3 ~]# /etc/init.d/mysql start Starting MySQL......SST in progress, setting sleep higher. SUCCESS! #####回到node1節點，進入mysql MariaDB [(none)]> show status like'wsrep_%'; +------------------------------+-------------------------------------------------------------+ | Variable_name | Value | +------------------------------+-------------------------------------------------------------+ | wsrep_local_state_uuid | 198c2664-8f88-11e5-bf9c-0e81c9575644 | | wsrep_protocol_version | 7 | | wsrep_last_committed | 0 | | wsrep_replicated | 0 | | wsrep_replicated_bytes | 0 | | wsrep_repl_keys | 0 | | wsrep_repl_keys_bytes | 0 | | wsrep_repl_data_bytes | 0 | | wsrep_repl_other_bytes | 0 | | wsrep_received | 10 | | wsrep_received_bytes | 758 | | wsrep_local_commits | 0 | | wsrep_local_cert_failures | 0 | | wsrep_local_replays | 0 | | wsrep_local_send_queue | 0 | | wsrep_local_send_queue_max | 1 | | wsrep_local_send_queue_min | 0 | | wsrep_local_send_queue_avg | 0.000000 | | wsrep_local_recv_queue | 0 | | wsrep_local_recv_queue_max | 1 | | wsrep_local_recv_queue_min | 0 | | wsrep_local_recv_queue_avg | 0.000000 | | wsrep_local_cached_downto | 18446744073709551615 | | wsrep_flow_control_paused_ns | 0 | | wsrep_flow_control_paused | 0.000000 | | wsrep_flow_control_sent | 0 | | wsrep_flow_control_recv | 0 | | wsrep_cert_deps_distance | 0.000000 | | wsrep_apply_oooe | 0.000000 | | wsrep_apply_oool | 0.000000 | | wsrep_apply_window | 0.000000 | | wsrep_commit_oooe | 0.000000 | | wsrep_commit_oool | 0.000000 | | wsrep_commit_window | 0.000000 | | wsrep_local_state | 4 | | wsrep_local_state_comment | Synced | | wsrep_cert_index_size | 0 | | wsrep_causal_reads | 0 | | wsrep_cert_interval | 0.000000 | | wsrep_incoming_addresses | 172.16.116.231:3306,172.16.116.232:3306,172.16.116.233:3306 | | wsrep_evs_delayed | | | wsrep_evs_evict_list | | | wsrep_evs_repl_latency | 0/0/0/0/0 | | wsrep_evs_state | OPERATIONAL | | wsrep_gcomm_uuid | 198b3495-8f88-11e5-8b30-6a22054488b1 | | wsrep_cluster_conf_id | 3 | | wsrep_cluster_size | 3 | | wsrep_cluster_state_uuid | 198c2664-8f88-11e5-bf9c-0e81c9575644 | | wsrep_cluster_status | Primary | | wsrep_connected | ON | | wsrep_local_bf_aborts | 0 | | wsrep_local_index | 0 | | wsrep_provider_name | Galera | | wsrep_provider_vendor | Codership Oy <[email protected]> | | wsrep_provider_version | 25.3.9(r3387) | | wsrep_ready | ON | | wsrep_thread_count | 2 | +------------------------------+-------------------------------------------------------------+
4、測試
///node1中添加1個數據庫
MariaDB [(none)]> create database node1;
Query OK, 1 row affected (0.01 sec)
///node2上查看
[root@node2 ~]# mysql
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| node1 |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
//node3上向node1數據庫中添加1個表test3，並插入數據
MariaDB [(none)]> use node1;
Database changed
MariaDB [node1]> create table test3(id int unsigned auto_increment not null primary key,name char(10));
Query OK, 0 rows affected (0.02 sec)
MariaDB [node1]> insert into test3 (name) value ('zhang'),('wang');
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
//回到node1上查看，並插入新的數據
MariaDB [(none)]> select * from node1.test3;
+----+-------+
| id | name |
+----+-------+
| 3 | zhang |
| 6 | wang |
+----+-------+
2 rows in set (0.00 sec)
MariaDB [(none)]> insert into node1.test3 (name) value ('li'),('chen');
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
//在node2上查看
MariaDB [(none)]> select * from node1.test3;
+----+-------+
| id | name |
+----+-------+
| 3 | zhang |
| 6 | wang |
| 7 | li |
| 10 | chen |
+----+-------+
4 rows in set (0.00 sec)通過上述測試可以看看3個節點都可以讀寫數據，即時同步；但對於自動增長的字段插入新數據，序號不連續，解決方法，只能定義全局的計數器來實現~
至此，Galera Cluster的高可用mysql集羣介紹完畢！
後續工作，可以加入keepalived+haproxy實現對Galera Cluster的進一步擴展，O(∩_∩)O~~~