MongoDB复制是将数据同步在多个服务器的过程。复制提供了数据的冗余备份，并在多个服务器上存储数据副本，提高了数据的可用性， 并可以保证数据的安全性。 复制还允许您从硬件故障和服务中断中恢复数据。
创建副本集时注意
- 版本: 各副本集服务器的MongoDB版本一致或支持同样的replSet功能
- 网络: 副本集内的每个成员都必须能够连接到其他成员(包括自身),启动时注意bind_ip --bind_ip_all.
配置副本集
- 1 建立配置文件
mongodb.conf
1 # Start MongoDB as a daemon on port 27017 2 3 port = 27017 4 fork = true 5 replSet = test_replica_set 6 dbpath = /datatest/db 7 logpath = /datatest/db/test.log 8 logappend = true 9
mongodb2.conf
2 3 port = 27017 4 fork = true 5 replSet = test_replica_set 6 dbpath = /datatest/db 7 logpath = /datatest/db/test.log 8 logappend = true 9
mongodb3.conf
2 3 port = 27017 4 fork = true 5 replSet = test_replica_set 6 dbpath = /datatest/db 7 logpath = /datatest/db/test.log 8 logappend = true 9
- 2 启动数据库
mac-abeen:bin abeen$ sudo ./mongod -f mongodb.conf about to fork child process, waiting until server is ready for connections. forked process: 37181 child process started successfully, parent exiting mac-abeen:bin abeen$ sudo ./mongod -f mongodb2.conf about to fork child process, waiting until server is ready for connections. forked process: 37185 child process started successfully, parent exiting mac-abeen:bin abeen$ sudo ./mongod -f mongodb3.conf about to fork child process, waiting until server is ready for connections. forked process: 37189 child process started successfully, parent exiting
- 3 初始化副本集
mac-abeen:bin abeen$ ./mongo --nodb MongoDB shell version: 3.2.8 > config = {} { } > config = {"_id": "test_replica_set", "members": [ {"_id": 0, "host": "192.168.0.10:27017"}, {"_id": 1, "host": "192.168.0.20:27017"}, {"_id": 2, "host": "192.168.0.30:27017"}]}
{ "_id" : "test_replica_set", "members" : [ { "_id" : 0, "host" : "192.168.0.10:27017" }, { "_id" : 1, "host" : "192.168.0.20:27017" }, { "_id" : 2, "host" : "192.168.0.30:27017" } ] } > db = (new Mongo("192.168.0.10:27017")).getDB("test") test > rs.initiate(config) { "ok" : 1 } test_replica_set:OTHER>
test_replica_set:PRIMARY> rs.config() { "_id" : "test_replica_set", "version" : 1, "protocolVersion" : NumberLong(1), "members" : [ { "_id" : 0, "host" : "192.168.0.10:27017", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 1, "tags" : { }, "slaveDelay" : NumberLong(0), "votes" : 1 }, { "_id" : 1, "host" : "192.168.0.20:27017", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 1, "tags" : { }, "slaveDelay" : NumberLong(0), "votes" : 1 }, { "_id" : 2, "host" : "192.168.0.30:27017", "arbiterOnly" : false, "buildIndexes" : true, "hidden" : false, "priority" : 1, "tags" : { }, "slaveDelay" : NumberLong(0), "votes" : 1 } ], "settings" : { "chainingAllowed" : true, "heartbeatIntervalMillis" : 2000, "heartbeatTimeoutSecs" : 10, "electionTimeoutMillis" : 10000, "getLastErrorModes" : { }, "getLastErrorDefaults" : { "w" : 1, "wtimeout" : 0 }, "replicaSetId" : ObjectId("5850f445c8cacd70496883b0") } }
- 4 写入数据并查看副本集数据
test_replica_set:PRIMARY> test_replica_set:PRIMARY> for (i=0; i < 100; i ){db.coll.insert({"count": i})} WriteResult({ "nInserted" : 1 }) test_replica_set:PRIMARY> db.coll.count() 100 test_replica_set:PRIMARY> db.coll.find().limit(5) { "_id" : ObjectId("5850f5f35f1a7d82c0b45b51"), "count" : 0 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b52"), "count" : 1 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b53"), "count" : 2 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b54"), "count" : 3 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b55"), "count" : 4 }
- 5 查看副本集是否有数据
mac-abeen:bin abeen$ ./mongo --port 27017 --host 192.168.0.20 MongoDB shell version: 3.2.8 connecting to: 192.168.0.20:27017/test
test_replica_set:SECONDARY> db.coll.find().limit(5) Error: error: { "ok" : 0, "errmsg" : "not master and slaveOk=false", "code" : 13435 } 设置连接可读取数据 test_replica_set:SECONDARY> db.setSlaveOk() 副本中已有数据 test_replica_set:SECONDARY> db.coll.find().limit(5) { "_id" : ObjectId("5850f5f35f1a7d82c0b45b53"), "count" : 2 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b55"), "count" : 4 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b52"), "count" : 1 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b54"), "count" : 3 } { "_id" : ObjectId("5850f5f35f1a7d82c0b45b51"), "count" : 0 }
修改副本集
rs.add("server-4:27017") //添加 rs.addArb("server-4:27017") //添加选举仲裁者 rs.add({"_id": 4, "host": "server-4:27017", "arbiterOnly": true) //添加选举仲裁者 rs.add({"_id": 5, "host": "server-5:27017", "priority": 0, "hidden": true) //添加隐藏成员 rs.remove("server-4:27017") //移除
修改副本集,通过rs.reconfig
rs.reconfig修改副本集成员时限制
- 不能修改成员的_id 字段
- 不能将接收rs.reconfig命令的成员(通常是主节点)的优先级设为0
- 不能仲裁者成员变为非仲裁者成员,反之亦然.
- 不能将buildIndexes: false的成员修改为buildIndexes: true 可以修改其他,比如host
var config = rs.config() config.members[1].host = "newsserver:27017" //修改host rs.reconfig(config)
