特點
- 同步複製
- 可以在任意節點上進行讀寫
- 自動控制成員，自動刪除故障節點
- 自動加入節點
- 真正給予行級別的併發複製
- 調度客戶連接
架構圖
mariadb 可以看做是常見的數據庫，負責連接應用(web, API 等）
單純的 mariadb 無法實現多個主服務器數據同步
多臺數據庫中數據同步由 wsrep 接口實現
最終目標，實現多個 MySQL 同時讀寫
wsrep API
wsrep API 是一種數據庫插件接口，比較類似一種應用程序，主要針對寫複製
該程序主要用於定義應用程序如何調用複製庫實現回寫
wsrep API 由支持改庫的應用程序動態裝載
全局事務ID(GTID)
wsrep API 描述下面複製模型，一個應用程序，如數據庫當前的一個對象，當前被客戶端修改，對象改變導致事務產生一系列的原子性改變， 在集羣中所有的節點都具備相同的對象，並由同步複製應用都各自節點，按照相同的順序產生相同變化從而實現數據同步
GTID 包含
一個 UUID 作爲對象標識及經歷改變的序號，序號會發生連續的改變
GTID 允許比較應用程序狀態，建立對象改變的順序，決定對象的變化是否需要更新 GTID
部署環境
node-1:192.168.200.4 mariadb：10.1.30 galera：25.3.22
node-2:192.168.200.5 mariadb：10.1.30 galera：25.3.22安裝mariadb+galera
[root@node-1 ~]# yum install MariaDB-server galera
[root@node-2 ~]# yum install MariaDB-server galera配置主節點node-1
[root@node-1 ~]# vi /etc/my.cnf
[mysqld]
max_connect_errors=1000
[root@node-1 ~]# vi /etc/my.cnf.d/server.cnf
[galera]
wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address=gcomm://
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0
wsrep_cluster_name="MariaDB_Cluster"
wsrep_node_address="192.168.200.4"
wsrep_sst_method=rsyn配置備份節點node-2
[root@node-2 ~]# vi /etc/my.cnf
[mysqld]
max_connect_errors=1000
[root@node-2 ~]# vi /etc/my.cnf.d/server.cnf
[galera]
# Mandatory settings
wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.200.4,192.168.200.5"
binlog_format=row
default_storage_engine=InnoDB
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0
wsrep_node_address="192.168.200.5"
wsrep_cluster_name="MariaDB_Cluster"
wsrep_sst_method=rsync啓動服務
[root@node-1 ~]# /bin/galera_new_cluster
[root@node-2 ~]# systemctl start mariadb測試集羣狀態
[root@node-1 ~]# mysql -uroot -p
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 | 0 |
| wsrep_cert_deps_distance | 0.000000 |
| wsrep_cert_index_size | 0 |
| wsrep_cert_interval | 0.000000 |
| wsrep_cluster_conf_id | 2 |
| wsrep_cluster_size | 2 |
| wsrep_cluster_state_uuid | 3fa7ddbb-6839-11e9-a6f5-2b4eac1b9da2 |
| wsrep_cluster_status | Primary |
| wsrep_commit_oooe | 0.000000 |
| wsrep_commit_oool | 0.000000 |
| wsrep_commit_window | 0.000000 |
| wsrep_connected | ON |
| wsrep_desync_count | 0 |
| wsrep_evs_delayed | |
| wsrep_evs_evict_list | |
| wsrep_evs_repl_latency | 0.000522839/0.0016527/0.00400798/0.00117158/6 |
| wsrep_evs_state | OPERATIONAL |
| wsrep_flow_control_paused | 0.000000 |
| wsrep_flow_control_paused_ns | 0 |
| wsrep_flow_control_recv | 0 |
| wsrep_flow_control_sent | 0 |
| wsrep_gcomm_uuid | 3fa68225-6839-11e9-9abe-478e95b9264a |
| wsrep_incoming_addresses | 192.168.200.4:3306,192.168.200.5:3306 |
| wsrep_last_committed | 0 |
| wsrep_local_bf_aborts | 0 |
| wsrep_local_cached_downto | 18446744073709551615 |
| wsrep_local_cert_failures | 0 |
| wsrep_local_commits | 0 |
| wsrep_local_index | 0 |
| wsrep_local_recv_queue | 0 |
| wsrep_local_recv_queue_avg | 0.166667 |
| wsrep_local_recv_queue_max | 2 |
| wsrep_local_recv_queue_min | 0 |
| wsrep_local_replays | 0 |
| wsrep_local_send_queue | 0 |
| wsrep_local_send_queue_avg | 0.000000 |
| wsrep_local_send_queue_max | 1 |
| wsrep_local_send_queue_min | 0 |
| wsrep_local_state | 4 |
| wsrep_local_state_comment | Synced |
| wsrep_local_state_uuid | 3fa7ddbb-6839-11e9-a6f5-2b4eac1b9da2 |
| wsrep_protocol_version | 7 |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy <[email protected]> |
| wsrep_provider_version | 25.3.22(r3764) |
| wsrep_ready | ON |
| wsrep_received | 6 |
| wsrep_received_bytes | 414 |
| wsrep_repl_data_bytes | 0 |
| wsrep_repl_keys | 0 |
| wsrep_repl_keys_bytes | 0 |
| wsrep_repl_other_bytes | 0 |
| wsrep_replicated | 0 |
| wsrep_replicated_bytes | 0 |
| wsrep_thread_count | 2 |
+------------------------------+-----------------------------------------------+
58 rows in set (0.00 sec)
#如果 "wsrep_local_state_comment" is "Synced" 則表明集羣創建成功。數據同步
#在node-1創建數據庫
[root@node-1 ~]# mysql -uroot -p
MariaDB [(none)]> create database galera_test;
Query OK, 1 row affected (0.06 sec)
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| galera_test |
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
#在node-2上查詢
[root@node-2 ~]# mysql -uroot -p
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| galera_test |
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
#可以查詢到galera_test數據庫，說明數據庫同步沒問題。