mongodb副本集及故障转移部署记录

工作原理

1.副本集之间的复制是通过oplog日志现实的.备份节点通过查询这个集合就可以知道需要进行复制的操作

2.oplog是节点中local库中的一个固定的集合,在默认情况下oplog初始化大小为空闲磁盘的5%.oplog是capped collection,所以当oplog的空间被占满时,会覆盖最初写入的日志

3.通过改变oplog文档的大小直接改变local所占磁盘空间的大小.可以在配置文件中设置oplogSize参数来指定oplog文档的大小。

4.通过oplog中的操作记录,把数据复制在备份节点.

5.主节点是集中接收写入操作的,MongoDB中的应用连接到主节点进行写入操作，然后记录在主节点操作oplog,从节点成员定期轮询复制此日志并将操作应用于其数据集。

常用命令

rs.conf() 查看副本集配置

rs.status() 查看副本集状态

rs.initiate(config) 初始化副本集

rs.isMaster() 查看是否为主节点

db.getMongo().setSlaveOk(); 赋予副本集副本节点查询数据的权限，副本节点执行

一、环境准备

操作系统centos6.5 mongodb版本3.6.6

ip地址主机名角色

192.168.1.230 mongodb01 副本集主节点

192.168.1.18 mongodb02 副本集副本节点

192.168.1.247 mongodb03 副本集副本节点

关闭3个服务器的防火墙及selinux

二、安装部署mongodb及副本集配置

1、安装部署mongodb

可参考：https://www.cnblogs.com/wusy/p/10405991.html

2、副本集配置

1）yum安装mongodb在做副本集时需在所有服务器配置文件加入以下配置：

replication:
replSetName: repset（副本集名，可自定义）

2）下载源码包，手动编译的方式则需加以下配置：

replSet=repset（副本集名）

3、初始化副本集

在任意一台节点初始化都可，但在哪一台做初始化，那么这一台就作为副本集的主节点，这里选择mongodb01（也可使用权重值来控制主副节点）

1）进入mongodb数据库

[root@mongodb01 ~]# mongo --host 192.168.1.230

2）定义副本集配置，这里的_id:repset要与配置文件中所指的副本集名称一致

>config={
... _id:"repset",
... members:[
... {_id:0,host:"192.168.1.230:27017"},
... {_id:1,host:"192.168.1.18:27017"},
... {_id:2,host:"192.168.1.247:27017"}
... ]
... }

{
"_id" : "repset",
"members" : [
{
"_id" : 0,
"host" : "192.168.1.230:27017"
},
{
"_id" : 1,
"host" : "192.168.1.18:27017"
},
{
"_id" : 2,
"host" : "192.18.1.247:27017"
}
]
}

3)初始化副本集配置

> rs.initiate(config)
{
"ok" : 1,
"operationTime" : Timestamp(1551502195, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1551502195, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

4）查看集群节点状态（health为1表明正常，为0表明异常）

repset:PRIMARY> rs.status()
{
"set" : "repset",
"date" : ISODate("2019-03-02T04:50:47.554Z"),
"myState" : 1,
"term" : NumberLong(1),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"appliedOpTime" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"durableOpTime" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
}
},
"lastStableCheckpointTimestamp" : Timestamp(1551502208, 1),
"members" : [
{
"_id" : 0,
"name" : "192.168.1.230:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 153,
"optime" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2019-03-02T04:50:38Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1551502207, 1),
"electionDate" : ISODate("2019-03-02T04:50:07Z"),
"configVersion" : 1,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "192.168.1.18:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 51,
"optime" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2019-03-02T04:50:38Z"),
"optimeDurableDate" : ISODate("2019-03-02T04:50:38Z"),
"lastHeartbeat" : ISODate("2019-03-02T04:50:47.382Z"),
"lastHeartbeatRecv" : ISODate("2019-03-02T04:50:46.242Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "192.168.1.247:27017",
"syncSourceHost" : "192.168.1.247:27017",
"syncSourceId" : 2,
"infoMessage" : "",
"configVersion" : 1
},
{
"_id" : 2,
"name" : "192.168.1.247:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 51,
"optime" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1551502238, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2019-03-02T04:50:38Z"),
"optimeDurableDate" : ISODate("2019-03-02T04:50:38Z"),
"lastHeartbeat" : ISODate("2019-03-02T04:50:47.382Z"),
"lastHeartbeatRecv" : ISODate("2019-03-02T04:50:46.183Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "192.168.1.230:27017",
"syncSourceHost" : "192.168.1.230:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 1
}
],
"ok" : 1,
"operationTime" : Timestamp(1551502238, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1551502238, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
repset:PRIMARY>

5）查看是否为主节点（可在其他节点执行查看）

repset:PRIMARY> rs.isMaster()
{
"hosts" : [
"192.168.1.230:27017",
"192.168.1.18:27017",
"192.168.1.247:27017"
],
"setName" : "repset",
"setVersion" : 1,
"ismaster" : true,
"secondary" : false,
"primary" : "192.168.1.230:27017",
"me" : "192.168.1.230:27017",
"electionId" : ObjectId("7fffffff0000000000000001"),
"lastWrite" : {
"opTime" : {
"ts" : Timestamp(1551502348, 1),
"t" : NumberLong(1)
},
"lastWriteDate" : ISODate("2019-03-02T04:52:28Z"),
"majorityOpTime" : {
"ts" : Timestamp(1551502348, 1),
"t" : NumberLong(1)
},
"majorityWriteDate" : ISODate("2019-03-02T04:52:28Z")
},
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 100000,
"localTime" : ISODate("2019-03-02T04:52:32.106Z"),
"logicalSessionTimeoutMinutes" : 30,
"minWireVersion" : 0,
"maxWireVersion" : 7,
"readOnly" : false,
"ok" : 1,
"operationTime" : Timestamp(1551502348, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1551502348, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

6）可登入副本集副本节点，并查看是否为主节点或副本节点

[root@mongodb02 ~]# mongo --host 192.168.1.18

repset:SECONDARY>

repset:SECONDARY> rs.isMaster()
{
"hosts" : [
"192.168.1.230:27017",
"192.168.1.18:27017",
"192.168.1.247:27017"
],
"setName" : "repset",
"setVersion" : 1,
"ismaster" : false,
"secondary" : true,
"primary" : "192.168.1.230:27017",
"me" : "192.168.1.18:27017",
"lastWrite" : {
"opTime" : {
"ts" : Timestamp(1551502458, 1),
"t" : NumberLong(1)
},
"lastWriteDate" : ISODate("2019-03-02T04:54:18Z"),
"majorityOpTime" : {
"ts" : Timestamp(1551502458, 1),
"t" : NumberLong(1)
},
"majorityWriteDate" : ISODate("2019-03-02T04:54:18Z")
},
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 100000,
"localTime" : ISODate("2019-03-02T04:54:27.819Z"),
"logicalSessionTimeoutMinutes" : 30,
"minWireVersion" : 0,
"maxWireVersion" : 7,
"readOnly" : false,
"ok" : 1,
"operationTime" : Timestamp(1551502458, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1551502458, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

三、登入副本集副本集节点验证数据复制功能（默认副本集的副本节点不能查看数据）

1、在主节点mongodb01上插入数据，在副本节点查看数据

repset:PRIMARY> use test
switched to db test

repset:PRIMARY> db.test.save({id:"one",name:"wushaoyu"})
WriteResult({ "nInserted" : 1 })

2、进入副本节点mongodb02查看主库插入的数据

repset:SECONDARY> use test
switched to db test
repset:SECONDARY> show dbs
2019-03-02T13:07:06.503+0800 E QUERY [js] Error: listDatabases failed:{
"operationTime" : Timestamp(1551503218, 1),
"ok" : 0,
"errmsg" : "not master and slaveOk=false",
"code" : 13435,
"codeName" : "NotMasterNoSlaveOk",
"$clusterTime" : {
"clusterTime" : Timestamp(1551503218, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:65:1
shellHelper.show@src/mongo/shell/utils.js:865:19
shellHelper@src/mongo/shell/utils.js:755:15
@(shellhelp2):1:1

注：上面出现了报错

因为主库插入的数据，从库是不具备读的权限的，所以要设置副本节点可以读

repset:SECONDARY> db.getMongo().setSlaveOk();

repset:SECONDARY> db.test.find()
{ "_id" : ObjectId("5c7a0f3a6698c70ef075f0a8"), "id" : "one", "name" : "wushaoyu" }

repset:SECONDARY> show tables
test

注：由此看到，副本节点已经把主节点的数据复制过来了（在mongodb03上做同样操作即可）

四、验证故障转移功能，停止当前副本主节点，验证高可用

先停止副本主节点，在查看副本节点的状态，

1）停止副本主节点的mongodb

[root@mongodb01 ~]# ps -ef |grep mongod
mongod 27170 1 0 12:48 ? 00:00:06 /usr/bin/mongod -f /etc/mongod.conf
root 27335 5388 0 13:15 pts/3 00:00:00 grep mongod

[root@mongodb01 ~]# kill -9 27170

2）登录其他两个副本集节点，查看是否推选出新的主节点

[root@mongodb02 ~]# mongo --host 192.168.1.18

repset:SECONDARY> rs.isMaster()
{
"hosts" : [
"192.168.1.230:27017",
"192.168.1.18:27017",
"192.168.1.247:27017"
],
"setName" : "repset",
"setVersion" : 1,
"ismaster" : false,
"secondary" : true,
"primary" : "192.168.1.247:27017",
"me" : "192.168.1.18:27017",
"lastWrite" : {
"opTime" : {
"ts" : Timestamp(1551503801, 1),
"t" : NumberLong(2)
},
"lastWriteDate" : ISODate("2019-03-02T05:16:41Z"),
"majorityOpTime" : {
"ts" : Timestamp(1551503801, 1),
"t" : NumberLong(2)
},
"majorityWriteDate" : ISODate("2019-03-02T05:16:41Z")
},
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 100000,
"localTime" : ISODate("2019-03-02T05:16:48.433Z"),
"logicalSessionTimeoutMinutes" : 30,
"minWireVersion" : 0,
"maxWireVersion" : 7,
"readOnly" : false,
"ok" : 1,
"operationTime" : Timestamp(1551503801, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1551503801, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

[root@mongodb03 ~]# mongo --host 192.168.1.247

repset:PRIMARY> rs.isMaster()
{
"hosts" : [
"192.168.1.230:27017",
"192.168.1.18:27017",
"192.168.1.247:27017"
],
"setName" : "repset",
"setVersion" : 1,
"ismaster" : true,
"secondary" : false,
"primary" : "192.168.1.247:27017",
"me" : "192.168.1.247:27017",
"electionId" : ObjectId("7fffffff0000000000000002"),
"lastWrite" : {
"opTime" : {
"ts" : Timestamp(1551503971, 1),
"t" : NumberLong(2)
},
"lastWriteDate" : ISODate("2019-03-02T05:19:31Z"),
"majorityOpTime" : {
"ts" : Timestamp(1551503971, 1),
"t" : NumberLong(2)
},
"majorityWriteDate" : ISODate("2019-03-02T05:19:31Z")
},
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 100000,
"localTime" : ISODate("2019-03-02T05:19:35.282Z"),
"logicalSessionTimeoutMinutes" : 30,
"minWireVersion" : 0,
"maxWireVersion" : 7,
"readOnly" : false,
"ok" : 1,
"operationTime" : Timestamp(1551503971, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1551503971, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

ps：发现主节点宕机之后，mongodb03为新推选出来的主节点

3）在新的主节点mongodb03插入数据，在mongodb02上查看是否同步

[root@mongodb03 ~]# mongo --host 192.168.1.247

repset:PRIMARY> use wsy
switched to db wsy
repset:PRIMARY> db.wsy.save({"name":"wsy"})
WriteResult({ "nInserted" : 1 })

[root@mongodb02 ~]# mongo --host 192.168.1.18

repset:SECONDARY> db.getMongo().setSlaveOk();
repset:SECONDARY> show tables
wsy

repset:SECONDARY> db.wsy.find()
{ "_id" : ObjectId("5c7a133007ebf60ac5870bae"), "name" : "wsy" }

由此可看出，数据同步成功

4）启动先前的mongodb01，查看状态，mongodb成为了当前主节点的副本节点，并且在它宕机期间插入的数据也同步了过来

[root@mongodb01 ~]# /etc/init.d/mongod start

[root@mongodb01 ~]# mongo --host 192.168.1.230

repset:SECONDARY> rs.isMaster()
{
"hosts" : [
"192.168.1.230:27017",
"192.168.1.18:27017",
"192.168.1.247:27017"
],
"setName" : "repset",
"setVersion" : 1,
"ismaster" : false,
"secondary" : true,
"primary" : "192.168.1.247:27017",
"me" : "192.168.1.230:27017",
"lastWrite" : {
"opTime" : {
"ts" : Timestamp(1551504771, 1),
"t" : NumberLong(2)
},
"lastWriteDate" : ISODate("2019-03-02T05:32:51Z"),
"majorityOpTime" : {
"ts" : Timestamp(1551504771, 1),
"t" : NumberLong(2)
},
"majorityWriteDate" : ISODate("2019-03-02T05:32:51Z")
},
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 100000,
"localTime" : ISODate("2019-03-02T05:32:59.225Z"),
"logicalSessionTimeoutMinutes" : 30,
"minWireVersion" : 0,
"maxWireVersion" : 7,
"readOnly" : false,
"ok" : 1,
"operationTime" : Timestamp(1551504771, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1551504771, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}

#开启副本节点读的权限

repset:SECONDARY> db.getMongo().setSlaveOk();
repset:SECONDARY> db.wsy.find()
{ "_id" : ObjectId("5c7a133007ebf60ac5870bae"), "name" : "wsy" }

注：在原来的主节点宕机期间，新选举出来的主机插入的数据，也会同步过来

mongodb副本集及故障转移部署记录

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