Nosql Mongodb之旅(25)—MongoDB Replica Sets增加节点

MongoDB Replica Sets 不仅提供高可用性的解决方案，它也同时提供负载均衡的解决方案，增减Replica Sets 节点在实际应用中非常普遍，例如当应用的读压力暴增时，3 台节点的环境已不能满足需求，那么就需要增加一些节点将压力平均分配一下。

增加节点

两种方式：一是通过oplog增加节点，二是通过数据库快照和oplog来增加节点

通过oplog增加节点

1、配置并启动新节点，启用28013这个端口给新的节点

rs1:PRIMARY>rs.add("localhost:28013")
1. {"ok":1}

（1）进行初始化

rs1:PRIMARY>rs.status()
1. {
2. "set":"rs1",
3. "date":ISODate("2012-05-31T12:17:44Z"),
4. "myState":1,248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "members":[
5. ……
6. "_id":3,248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "name":"localhost:28013",108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "health":0,248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "state":6,108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "stateStr":"(notreachable/healthy)",248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "uptime":0,108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "optime":{
7. "t":0,108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "i":0
8. },108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "optimeDate":ISODate("1970-01-01T00:00:00Z"),248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "lastHeartbeat":ISODate("2012-05-31T12:17:43Z"),108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "errmsg":"stillinitializing"
9. }
10. ],248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "ok":1
11. }

"date":ISODate("2012-05-31T12:18:07Z"),108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "health":1,248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "state":3,108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "stateStr":"RECOVERING",248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "uptime":16,248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "lastHeartbeat":ISODate("2012-05-31T12:18:05Z"),108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "errmsg":"initialsyncneedamembertobeprimaryorsecondary
1. todoourinitialsync"
2. }
3. ],108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "ok":1
4. }

"date":ISODate("2012-05-31T12:18:08Z"),248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "uptime":17,248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "t":1338466661000,108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "i":1
1. "optimeDate":ISODate("2012-05-31T12:17:41Z"),248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "lastHeartbeat":ISODate("2012-05-31T12:18:07Z"),108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "errmsg":"initialsyncdone"
2. （4）节点添加完成，状态正常
   
   "date":ISODate("2012-05-31T12:18:10Z"),248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "state":2,108); list-style:decimal-leading-zero outside; color:inherit; line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "stateStr":"SECONDARY",248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "uptime":19,248); line-height:21px; margin:0px!important; padding:0px 3px 0px 10px!important"> "lastHeartbeat":ISODate("2012-05-31T12:18:09Z")
   1. 4、验证数据已经同步过来
      
      [root@localhostdata]#/Apps/mongo/bin/mongo-port28013
      1. MongoDBshellversion:1.8.1
      2. connectingto:127.0.0.1:28013/test
      3. rs1:SECONDARY>rs.slaveOk()
      4. rs1:SECONDARY>db.c1.find()
      5. {"_id":ObjectId("4fc760d2383ede1dce14ef86"),"age":10}
      6. rs1:SECONDARY>
      通过数据库快照和oplog增加节点

      通过oplog 直接进行增加节点操作简单且无需人工干预过多，但oplog 是capped collection，采用循环的方式进行日志处理，所以采用oplog 的方式进行增加节点，有可能导致数据的不一致，因为日志中存储的信息有可能已经刷新过了。不过没关系，我们可以通过数据库快照(--fastsync)和oplog 结合的方式来增加节点，这种方式的操作流程是，先取某一个复制集成员的物理文件来做为初始化数据，然后剩余的部分用oplog 日志来追，最终达到数据一致性。

      （1）取某一个复制集成员的物理文件来作为初始化数据
      

      [root@localhost~]#scp-r/data/data/r3/data/data/r4
      1. [root@localhost~]#echo"thisisrs1supersecretkey">/data/key/r4
      2. [root@localhost~]#chmod600/data/key/r4
      （2）在取完物理文件后，在c1集中插入一条新文档，用于最后验证此更新也同步了
      
      rs1:PRIMARY>db.c1.find()
      1. rs1:PRIMARY>db.c1.insert({age:20})
      2. rs1:PRIMARY>db.c1.find()
      3. {"_id":ObjectId("4fc760d2383ede1dce14ef86"),"age":10}
      4. {"_id":ObjectId("4fc7748f479e007bde6644ef"),"age":20}
      5. rs1:PRIMARY>
      （3）启用28014这个端口给新的节点
      
      /Apps/mongo/bin/mongod--replSetrs1--keyFile/data/key/r4--fork--port28014--dbpath
      1. /data/data/r4--logpath=/data/log/r4.log--logappend--fastsync
      （4）添加28014节点
      
      rs1:PRIMARY>rs.add("localhost:28014")
      1. （5）验证数据已经同步过来
         
         [root@localhostdata]#/Apps/mongo/bin/mongo-port28014
         1. connectingto:127.0.0.1:28014/test
         2. {"_id":ObjectId("4fc7748f479e007bde6644ef"),"age":20}
         3. rs1:SECONDARY

         （编辑：李大同）

         【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!