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MongoDB：Replica Set 增加节点

• 数据库

前一篇 blog 介绍了三节点 Replica Set 环境的搭建，那么出于各种原因，可能需要增加 mongdb 节点，例如原来是单节点，为了具有高可用，需要增加节点，那么接下来学习增加节点的操作：

一 准备

  1. 已经有一套 Replica Set 环境：
  2. 具有适当容量的另一套 mongodb 系统，以满足数据存储需求，并且网络通；

二 现有环境信息

2.1 数据情况

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[mongo@redhatB mongodb]$ mongo 127.0.0.1:27018  
MongoDB shell version: 2.2.1  
connecting to: 127.0.0.1:27018/test  

rs0:PRIMARY> show collections;  
system.indexes  
test_1  
things

rs0:PRIMARY> show dbs;  
local 0.078125GB  
test 0.0625GB

rs0:PRIMARY> db.things.find();  
{ "_id" : ObjectId("50ae202524a46399c488c0c6"), "id" : 1, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0c7"), "id" : 2, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0c8"), "id" : 3, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0c9"), "id" : 4, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0ca"), "id" : 5, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0cb"), "id" : 6, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0cc"), "id" : 7, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0cd"), "id" : 8, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0ce"), "id" : 9, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0cf"), "id" : 10, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d0"), "id" : 11, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d1"), "id" : 12, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d2"), "id" : 13, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d3"), "id" : 14, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d4"), "id" : 15, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d5"), "id" : 16, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d6"), "id" : 17, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d7"), "id" : 18, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d8"), "id" : 19, "name" : "aaa" }  
{ "_id" : ObjectId("50ae202524a46399c488c0d9"), "id" : 20, "name" : "aaa" }

2.2 Replica Set 节点信息

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rs0:PRIMARY> rs.conf();  
{  
 "_id" : "rs0",  
 "version" : 3,  
 "members" : [  
 {  
 "_id" : 0,  
 "host" : "redhatB.example.com:27018"  
 },  
 {  
 "_id" : 1,  
 "host" : "redhatB.example.com:27019"  
 },  
 {  
 "_id" : 2,  
 "host" : "redhatB.example.com:27020"  
 }  
 ]  
}

备注：从上面看出，目前 Replica Set 共有 3 节点。

三 增加节点

3.1 创建数据目录

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mkdir -p /mongodb/data04

3.2 创建新从节点配置文件

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touch /mongodb/data04/mongodb_27021.conf， 写入以下：
fork = true  
port = 27021  
dbpath = /mongodb/data04  
logpath = /mongodb/data04/mongo.log  
logappend = true  
replSet = rs0

3.3 启动新从节点

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[mongo@redhatB mongodb]$ mongod -f /mongodb/data04/mongodb_27021.conf  
forked process: 11733  
all output going to: /mongodb/data04/mongo.log  
child process started successfully, parent exiting

3.4 连接主节点

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[mongo@redhatB mongodb]$ mongo 127.0.0.1:27018  
MongoDB shell version: 2.2.1  
connecting to: 127.0.0.1:27018/test  
rs0:PRIMARY>

备注：根据“rs0:PRIMARY”标识，即可确认为主节点，也可通过以下命令确认是否是主节点。

3.5 判断当前库是否是主节点

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rs0:PRIMARY> rs.isMaster();{  
 "setName" : "rs0",  
 "ismaster" : true,  
 "secondary" : false,  
 "hosts" : [  
 "redhatB.example.com:27018",  
 "redhatB.example.com:27020",  
 "redhatB.example.com:27019"  
 ],  
 "primary" : "redhatB.example.com:27018",  
 "me" : "redhatB.example.com:27018",  
 "maxBsonObjectSize" : 16777216,  
 "localTime" : ISODate("2012-11-22T13:04:36.501Z"),  
 "ok" : 1  
}

3.6 增加新从节点到 Replica Set

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rs0:PRIMARY> rs.add("redhatB.example.com:27021");  
{ "ok" : 1 }

3.7 再次查看 Replica Set 配置

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rs0:PRIMARY> rs.conf();  
{  
 "_id" : "rs0",  
 "version" : 4,  
 "members" : [  
 {  
 "_id" : 0,  
 "host" : "redhatB.example.com:27018"  
 },  
 {  
 "_id" : 1,  
 "host" : "redhatB.example.com:27019"  
 },  
 {  
 "_id" : 2,  
 "host" : "redhatB.example.com:27020"  
 },  
 {  
 "_id" : 3,  
 "host" : "redhatB.example.com:27021"  
 }  
 ]  
}

备注：新节点已经加入 Replica Set 了，到了这步已完成增加节点所有步骤，接下来验证下新节点。

四 测试

4.1 登陆新节点

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[mongo@redhatB mongodb]$ mongo 127.0.0.1:27021  
MongoDB shell version: 2.2.1  
connecting to: 127.0.0.1:27021/test  
rs0:SECONDARY> show dbs;  
local 0.125GB  
test 0.0625GB

rs0:SECONDARY> show collections;  
Thu Nov 22 21:08:20 uncaught exception: error: { "$err" : "not master and slaveOk=false", "code" : 13435 }

4.2 开启从节点只读

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rs0:SECONDARY> rs.slars.slaveOk();

4.3 查看是否有数据

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rs0:SECONDARY> show collections;  
system.indexes  
test_1  
things
rs0:SECONDARY> db.things.count();  
30

备注：增加节点后，新节点会自动从主节点复制数据。

四 参考

http://docs.mongodb.org/manual/tutorial/expand-replica-set/#procedure-assumption-add-member-rs
http://docs.mongodb.org/manual/administration/replica-sets/#replica-set-admin-procedure-add-member

原创文章，作者：奋斗，如若转载，请注明出处：https://blog.ytso.com/237922.html

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