沒有看懂你的意思，如果是想創建獨立的三個集群，是不可以的，cluster的集群主要分三部分，管理節點、計算節點、存儲節點，其中所有的管理操作都在管理節點上進行，如果你已經有了一個集群了，該集群下有一個數據庫，創建新的數據庫只不過是給數據庫增加了兩個實例（oracle的叫法，實例），而不是新創建了兩個集群。
如果想新創建集群，需要保證有新的管理節點、計算節點和存儲節點。在此給你提個建議，盡量不要把多個項目的數據庫放在同一個集群下，很麻煩的，我們公司的項目就因為甲方資源緊張，沒辦法，三個項目用了一個cluster的集群，結果只要其中一個項目使用數據庫資源過大，就會把三個項目一起影響。
所以如果資源足夠的話，盡量拆成多個集群。

MYSQLcluster集群，在sql節點寫入，是如何把數據存儲到數據節點的？
數據節點實際就是單個的數據庫實例而已，所以數據存儲和一般實例沒有太多區別，如果你的意思是怎么保證數據的存儲一致性，那這個話就多了，不過，其實當做master-slave的高級模式來理解就好了，只是沒有使用binlog的動態轉換分發而已

如何搭建MySQL InnoDB Cluster

安裝mysql server和mysql-shell

rpm -ivh https://dev.mysql.com/get/mysql57-community-release-el6-10.noarch.rpm

yum install -y mysql-community-server mysql-shell

啟動mysql服務，并修改root密碼

[root@10-186-23-95 ~]# /etc/init.d/mysqld start

Initializing MySQL database:                               [  OK  ]

Installing validate password plugin:                       [  OK  ]

Starting mysqld:                                           [  OK  ]

[root@10-186-23-95 ~]# mysql -p$(awk  '/temporary password/{print $NF}' /var/log/mysqld.log) -e "set password='Actionsky@888'"

如果系統python版本低于2.7，需要升級至2.7，mysqlprovsion命令需要

sh -c 'wget -qO- 

http://people.redhat.com/bkabrda/scl_python27.repo >> 

/etc/yum.repos.d/scl.repo'

yum install -y python27

scl enable python27 bash

python --version

配置Group Replication模式，dba.configureLocalInstance 會設置必要配置參數并持久化配置

[root@10-186-23-95 ~]# mysqlsh

Welcome to MySQL Shell 1.0.9

Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type '\help', '\h' or '\?' for help, type '\quit' or '\q' to exit.

Currently in JavaScript mode. Use \sql to switch to SQL mode and execute queries.

mysql-js> dba.configureLocalInstance('root@localhost:3306')

Please provide the password for 'root@localhost:3306':

Detecting the configuration file...

Found configuration file at standard location: /etc/my.cnf

Do you want to modify this file? [Y|n]:

Validating instance...

注意：以上操作在每個數據庫節點都需要做一遍。

創建InnoDB Cluster，執行dba.createCluster('mycluster')會包含以下操作

• 在連接的實例上創建mysql.mysql_innodb_cluster_metadata存儲元數據信息

• 驗證配置信息

• 將此節點注冊成seed節點

• 創建必要的管理賬號

• 啟動 Group Replication

mysql-js> \c [email protected]   #必須連接某個數據節點

Creating a Session to '[email protected]'

Enter password:

Classic Session successfully established. No default schema selected.

mysql-js> dba.createCluster('mycluster')

A new InnoDB cluster will be created on instance '[email protected]:3306'.

Creating InnoDB cluster 'mycluster' on '[email protected]:3306'...

Adding Seed Instance...

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.

<Cluster:mycluster>

mysql-js> var cluster=dba.getCluster('mycluster')

mysql-js> cluster.addInstance('[email protected]:3306')  #添加其他節點

A new instance will be added to the InnoDB cluster. Depending on the amount of

data on the cluster this might take from a few seconds to several hours.

Please provide the password for '[email protected]:3306':

Adding instance to the cluster ...

The instance '[email protected]:3306' was successfully added to the cluster.

mysql-js> cluster.addInstance('[email protected]:3306')

A new instance will be added to the InnoDB cluster. Depending on the amount of

data on the cluster this might take from a few seconds to several hours.

Please provide the password for '[email protected]:3306':

Adding instance to the cluster ...

The instance '[email protected]:3306' was successfully added to the cluster.

mysql-js> cluster.status()

{

"clusterName": "mycluster",

"defaultReplicaSet": {

"name": "default",

"primary": "10.186.23.95:3306",

"status": "OK",

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

"topology": {

"10.186.23.94:3306": {

"address": "10.186.23.94:3306",

"mode": "R/O",

"readReplicas": {},

"role": "HA",

"status": "ONLINE"

},

"10.186.23.95:3306": {

"address": "10.186.23.95:3306",

"mode": "R/W",

"readReplicas": {},

"role": "HA",

"status": "ONLINE"

},

"10.186.23.96:3306": {

"address": "10.186.23.96:3306",

"mode": "R/O",

"readReplicas": {},

"role": "HA",

"status": "ONLINE"

}

}

}

}

安裝配置MySQL Router

[root@10-186-23-97 ~]# yum install -y mysql-router

[root@10-186-23-97 ~]# mysqlrouter --bootstrap [email protected]:3306 --user=mysqlrouter

Please enter MySQL password for root:

Bootstrapping system MySQL Router instance...

MySQL Router  has now been configured for the InnoDB cluster 'mycluster'.

The following connection information can be used to connect to the cluster.

Classic MySQL protocol connections to cluster 'mycluster':

- Read/Write Connections: localhost:6446

- Read/Only Connections: localhost:6447

X protocol connections to cluster 'mycluster':

- Read/Write Connections: localhost:64460

- Read/Only Connections: localhost:64470

[root@10-186-23-97 ~]# mysqlsh --uri root@localhost:6446

Creating a Session to 'root@localhost:6446'

Enter password:

Classic Session successfully established. No default schema selected.

Welcome to MySQL Shell 1.0.9

Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type '\help', '\h' or '\?' for help, type '\quit' or '\q' to exit.

Currently in JavaScript mode. Use \sql to switch to SQL mode and execute queries.

mysql-js> \sql

Switching to SQL mode... Commands end with ;

mysql-sql> select @@hostname;

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

| @@hostname                 |

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

| 10-186-23-94.actionsky.com |

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

1 row in set (0.00 sec)

可能遇到的問題

• 節點gtid 異常

如果節點在加入集群前，執行了寫操作，加入集群時會報錯

Please provide the password for '[email protected]:3306':

Adding instance to the cluster ...

Cluster.addInstance: WARNING: Not running locally on the server and can not access its error log.

ERROR:

Group Replication join failed.

ERROR: Error joining instance to cluster: '10.186.23.96@3306' - Query failed. 3092 (HY000): The server is not configured properly to be an active member of the group. Please see more details on error log.. Query: START group_replication (RuntimeError)

節點的錯誤日志中會出現

2017-05-09T06:49:57.301003Z 0 [ERROR] Plugin group_replication reported: 'This member has more executed transactions than those present in the group. Local transactions: 605da5eb-347d-11e7-b68b-bef8d5ac5be4:1,

cf2fe6ca-3460-11e7-aab3-bef8d5ac5be4:1-7 > Group transactions: 8399a91c-3483-11e7-b68b-bef8d5ac5be4:1-5,

cf2fe6ca-3460-11e7-aab3-bef8d5ac5be4:1-15'

解決辦法，登錄到此節點執行reset master

• python版本異常

第一次安裝時沒有檢查python版本，配置實例時出錯，但未輸出具體錯誤。

mysql-py> dba.configure_local_instance('root@localhost:3306')

Please provide the password for 'root@localhost:3306':

Detecting the configuration file...

Found configuration file at standard location: /etc/my.cnf

Do you want to modify this file? [Y|n]: Y

Validating instance...

The issues above can be fixed dynamically to get the server ready for InnoDB Cluster.

{

"errors": [],

"restart_required": false,

"status": "error"

}

后來通過查看mysqlsh的日志，發現錯誤原因

less ~/.mysqlsh/mysqlsh.log

...

2017-05-09 04:24:27: Error: DBA: mysqlprovision exited with error code (1) : ERROR: The __main__ gadget requires Python version 2.7.0 or higher and lower than 4.0.0. The version of Python detected was 2.6.6. You may need to install or redirect the execution of this utility to an environment that includes a compatible Python version.

...

• 重啟節點后需要手動重新加入集群

mysql-js> var cluster = dba.getCluster()

mysql-js> cluster.status()

{

...

"10.186.23.96:3306": {

"address": "10.186.23.96:3306",

"mode": "R/O",

"readReplicas": {},

"role": "HA",

"status": "(MISSING)"

}

}

}

}

mysql-js> cluster.rejoinInstance('[email protected]:3306')

mysql-js> cluster.status()

{

...

"10.186.23.96:3306": {

"address": "10.186.23.96:3306",

"mode": "R/O",

"readReplicas": {},

"role": "HA",

"status": "ONLINE"

}

}

}

}

• 集群所有節點發生重啟

當集群的所有節點都offline，直接獲取集群信息失敗，如何重新恢復集群

mysql-js> var cluster=dba.getCluster('mycluster')

Dba.getCluster: This function is not available through a session to a standalone instance (RuntimeError)

執行rebootClusterFromCompleteOutage命令，可恢復集群

mysql-js> dba.rebootClusterFromCompleteOutage('mycluster')

Reconfiguring the cluster 'mycluster' from complete outage...

The instance '10.186.23.96:3306' was part of the cluster configuration.

Would you like to rejoin it to the cluster? [y|N]: y

The instance '10.186.23.94:3306' was part of the cluster configuration.

Would you like to rejoin it to the cluster? [y|N]: y

The cluster was successfully rebooted.

• 腦裂場景

當集群中有部分節點出現UNREACHABLE狀態，此時集群無法做出決策，，會出現以下局面，此時只剩下一個活躍節點，此節點只能提供查詢，無法寫入，執行寫入操作會hang住。

修復這種狀態，需要執行forceQuorumUsingPartitionOf指定當前活躍節點(如果是多個則選擇primary node)，此時活躍節點可以提供讀寫操作，然后將其他節點加入此集群。

節點有哪狀態

• ONLINE  - 節點狀態正常。

• OFFLINE  -   實例在運行，但沒有加入任何Cluster。

• RECOVERING - 實例已加入Cluster，正在同步數據。

• ERROR  -  同步數據發生異常。

• UNREACHABLE -  與其他節點通訊中斷，可能是網絡問題，可能是節點crash。

• MISSING 節點已加入集群，但未啟動group replication

集群有哪些狀態

• OK – 所有節點處于online狀態，有冗余節點。

• OK_PARTIAL – 有節點不可用，但仍有冗余節點。

• OK_NO_TOLERANCE – 有足夠的online節點，但沒有冗余，例如：兩個節點的Cluster，其中一個掛了，集群就不可用了。

• NO_QUORUM – 有節點處于online狀態，但達不到法定節點數，此狀態下Cluster無法寫入，只能讀取。

• UNKNOWN – 不是online或recovering狀態，嘗試連接其他實例查看狀態。

• UNAVAILABLE – 組內節點全是offline狀態，但實例在運行，可能實例剛重啟還沒加入Cluster。

最后附一張集群狀態圖，restoreFromCompleteOutage在GA版本改成rebootClusterFromCompleteOutage。