光憑這句話，看不出來MGR的意思。但是，在這句話前面就應該曾經把這個簡稱的全名寫出來過。可以自己去查檢視。

MySQL Group Replication（下簡稱MGR）準確來說是官方推出的高知可用解決方案，基於原生複製技術，並以外掛的方式提供。

1、使用前，關掉防火牆，包括 selinux，firewalld，或者 MySQL 企業版的firewall（如果用了企業版的話）2、兩臺機器：（4 臺 MySQL 例項）192.168.2.219 centos-ytt57-1 3311/3312192.168.2.229 centos-ytt57-2 3311/33123、安裝 MySQL（兩臺都裝）, MySQL Shell（任意一臺）, mysqlrouter(任意一臺，官方建議和應用程式裝在一個伺服器上)yum install mysql-community-server mysql-shell mysql-router-community

4、搭建 InnoDB-Cluster（兩臺都裝）

1. 配置檔案如下：shell>vi /etc/my.cnfmaster-info-repository=tablerelay-log-info-repository=tablegtid_mode=ONenforce_gtid_consistency=ONbinlog_checksum=NONElog_slave_updates=ONbinlog_format=ROWtransaction_write_set_extraction=XXHASH642. 系統 HOSTS 配置（兩臺都配）

shell>vi /etc/hosts

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4

::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.2.219 centos-ytt57-2

192.168.2.229 centos-ytt57-3

用 MySQL coalesce 函式確認下 report-host 是否設定正確(root@localhost) : [(none)] >SELECT coalesce(@@report_host, @@hostname) as r;+----------------+| r |+----------------+| centos-ytt57-1 |+----------------+1 row in set (0.00 sec)

3. 建立管理員使用者搭建 GROUP REPLICATION （四個節點都要）

create user root identified by "Root@123";grant all on *.* to root with grant option;flush privileges;

4. MySQLsh 連線其中一臺節點：

[root@centos-ytt57-1 mysql]# mysqlsh root@localhost:3321

5. 檢查配置正確性：（如果這裡不顯示 OK，把對應的引數加到配置檔案重啟 MySQL 再次檢查）dba.checkInstanceConfiguration("root@centos-ytt57-2:3311");dba.checkInstanceConfiguration("root@centos-ytt57-2:3312");dba.checkInstanceConfiguration("root@centos-ytt57-3:3311");dba.checkInstanceConfiguration("root@centos-ytt57-3:3312");mysqlsh 執行檢測

[root@centos-ytt57-1 mysql]# mysqlsh --log-level=8 root@localhost:3311

MySQL localhost:3311 ssl JS > dba.checkInstanceConfiguration("root@centos-ytt57-2:3311")

{

"status": "ok"

}

6. 建立叢集，節點 1 上建立。（結果顯示 Cluster successfully created 表示成功）

MySQL localhost:3311 ssl JS > var cluster = dba.createCluster("ytt_mgr");

Cluster successfully created. Use Cluster.addInstance() to add MySQL instances.

At least 3 instances are needed for the cluster to be able to withstand up to

one server failure.

7. 新增節點 2，3，4（全部顯示 OK，表示新增成功）MySQL localhost:3311 ssl JS > cluster.addInstance("root@centos-ytt57-2:3312");MySQL localhost:3311 ssl JS > cluster.addInstance("root@centos-ytt57-3:3311");MySQL localhost:3311 ssl JS > cluster.addInstance("root@centos-ytt57-3:3312");

8. 檢視拓撲圖：（describe 簡單資訊，status 詳細描述）

MySQL localhost:3311 ssl JS > cluster.describe()

{

"clusterName": "ytt_mgr",

"defaultReplicaSet": {

"name": "default",

"topology": [

{

"address": "centos-ytt57-2:3311",

"label": "centos-ytt57-2:3311",

"role": "HA",

"version": "8.0.17"

},

{

"address": "centos-ytt57-2:3312",

"label": "centos-ytt57-2:3312",

"role": "HA",

"version": "8.0.17"

},

{

"address": "centos-ytt57-3:3311",

"label": "centos-ytt57-3:3311",

"role": "HA",

"version": "8.0.17"

},

{

"address": "centos-ytt57-3:3312",

"label": "centos-ytt57-3:3312",

"role": "HA",

"version": "8.0.17"

}

],

"topologyMode": "Single-Primary"

}

}

MySQL localhost:3311 ssl JS > cluster.status()

"clusterName": "ytt_mgr",

"defaultReplicaSet": {

"name": "default",

"primary": "centos-ytt57-2:3311",

"ssl": "REQUIRED",

"status": "OK",

"statusText": "Cluster is ONLINE and can tolerate up to ONE failure.",

"topology": {

"centos-ytt57-2:3311": {

"address": "centos-ytt57-2:3311",

"mode": "R/W",

"readReplicas": {},

"role": "HA",

"status": "ONLINE",

"version": "8.0.17"

},

"centos-ytt57-2:3312": {

"address": "centos-ytt57-2:3312",

"mode": "R/O",

"readReplicas": {},

"role": "HA",

"status": "ONLINE",

"version": "8.0.17"

},

"centos-ytt57-3:3311": {

"address": "centos-ytt57-3:3311",

"mode": "R/O",

"readReplicas": {},

"role": "HA",

"status": "ONLINE",

"version": "8.0.17"

},

"centos-ytt57-3:3312": {

"address": "centos-ytt57-3:3312",

"mode": "R/O",

"readReplicas": {},

"role": "HA",

"status": "ONLINE",

"version": "8.0.17"

}

},

"topologyMode": "Single-Primary"

},

"groupInformationSourceMember": "centos-ytt57-2:3311"

9. 簡單測試下資料是否同步

(root@localhost) : [(none)] >create database ytt;

Query OK, 1 row affected (0.03 sec)

(root@localhost) : [(none)] >use ytt;

Database changed

(root@localhost) : [ytt] >create table p1(id int primary key, log_time datetime);

Query OK, 0 rows affected (0.08 sec)

(root@localhost) : [ytt] >insert into p1 values (1,now());

Query OK, 1 row affected (0.04 sec)

(root@localhost) : [ytt] >show master status;

+---------------+----------+--------------+------------------+-------------------------------------------+

| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |

+---------------+----------+--------------+------------------+-------------------------------------------+

| mysql0.000001 | 25496 | | | 6c7bb9db-b759-11e9-a9c0-0800276cf0fc:1-41 |

+---------------+----------+--------------+------------------+-------------------------------------------+

1 row in set (0.00 sec)

檢視其他三個節點

(root@localhost) : [ytt] >show tables;

+---------------+

| Tables_in_ytt |

+---------------+

| p1 |

+---------------+

1 row in set (0.00 sec)

(root@localhost) : [ytt] >select * from p1;

+----+---------------------+

| id | log_time |

+----+---------------------+

| 1 | 2019-08-05 16:44:20 |

+----+---------------------+

1 row in set (0.00 sec)

停掉主節點：[root@centos-ytt57-2 mysql0]# systemctl stop mysqld@0

現在檢視，主節點已經變為本機 3312節點"centos-ytt57-2:3312": { "address": "centos-ytt57-2:3312", "mode": "R/W", "readReplicas": {}, "role": "HA", "status": "ONLINE"}

10. 報錯處理

錯誤日誌裡顯示2019-08-05T09:01:35.125591Z 0 [ERROR] Plugin group_replication reported: "The group name option is mandatory"2019-08-05T09:01:35.125622Z 0 [ERROR] Plugin group_replication reported: "Unable to start Group Replication on boot"

同時用 cluster.rescan() 掃描，發現The instance "centos-ytt57-2:3311" is no longer part of the ReplicaSet.

重新加入此節點到叢集：cluster.rejoinInstance("centos-ytt57-2:3311")

再次執行cluster.status()檢視叢集狀態："status": "OK",11. 移除和加入cluster.removeInstance("centos-ytt57-3:3312");The instance "centos-ytt57-3:3312" was successfully removed from the cluster.cluster.addInstance("centos-ytt57-3:3312");The instance "centos-ytt57-3:3312" was successfully added to the cluster.

12. 用 mysqlrouter 生成連線 MGR 相關資訊。涉及到兩個使用者：--user=mysqlrouter 是使用mysqlrouter的系統使用者自動建立的MySQL 使用者是用來與MGR通訊的使用者。如果想檢視這個使用者的使用者名稱以及密碼，就加上--force-password-validation，不過一般也沒有必要檢視。