MongoDB高可用架构：深入解析ReplicaSet机制

mongodb高可用性架构---Replica Set Replica Set使用的是n个mongod节点&＃xff0c;构建具备自动的容错功能(auto-failover),自动恢复的(auto-recovery)的高可用方案。 使用Replica Set来实现读写分离。通过在连接时指定或者在主库指定slaveOk&＃xff0c;由Secondary来分担读的压力&＃xff0c;Primary只承担写操作。 对于Replica Set中的secondary 节点默认是不可读的。 环境如下&＃xff1a; 192.168.198.131 192.168.198.129 192.168.198.132 分别在三台服务器上安装mongod服务&＃xff0c;安装如下&＃xff1a; # wget http://fastdl.mongodb.org/linux/mongodb-linux-x86_64-2.0.3.tgz # tar zxvf mongodb-linux-x86_64-2.0.3.tgz -C ../software/ # ln -s mongodb-linux-x86_64-2.0.3 /usr/local/mongodb # useradd mongodb # mkdir -p /data/mongodb/myset # cd /usr/local/mongodb/bin # ./mongod --replSet myset --dbpath /data/mongodb/myset --oplogSize 100 --logpath /data/mongodb/myset/myset.log --logappend --fork # ./mongo //任选一台执行以下内容 > config&＃61;{_id:"myset",members:[ ... {_id:0,host:"192.168.198.131:27017"}, ... {_id:1,host:"192.168.198.129:27017"}, ... {_id:2,host:"192.168.198.132:27017",arbiterOnly:true}]} 以下输出内容&＃xff1a; { "_id" : "myset", "members" : [ { "_id" : 0, "host" : "192.168.198.131:27017" }, { "_id" : 1, "host" : "192.168.198.129:27017" }, { "_id" : 2, "host" : "192.168.198.132:27017", "arbiterOnly" : true } ] } > rs.initiate(config) //初始化 以下输出内容&＃xff1a; { "info" : "Config now saved locally. Should come online in about a minute.", "ok" : 1 } > rs.conf() //查看配置内容 { "_id" : "myset", "version" : 1, "members" : [ { "_id" : 0, "host" : "192.168.198.131:27017" }, { "_id" : 1, "host" : "192.168.198.129:27017" }, { "_id" : 2, "host" : "192.168.198.132:27017", "arbiterOnly" : true } ] } > rs.status() //查看状态信息 { "set" : "myset", "date" : ISODate("2012-03-01T08:45:01Z"), "myState" : 1, "members" : [ { "_id" : 0, "name" : "192.168.198.131:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "optime" : { "t" : 1330591378000, "i" : 1 }, "optimeDate" : ISODate("2012-03-01T08:42:58Z"), "self" : true }, { "_id" : 1, "name" : "192.168.198.129:27017", "health" : 1, "state" : 2, "stateStr" : "SECONDARY", "uptime" : 121, "optime" : { "t" : 1330591378000, "i" : 1 }, "optimeDate" : ISODate("2012-03-01T08:42:58Z"), "lastHeartbeat" : ISODate("2012-03-01T08:45:01Z"), "pingMs" : 0 }, { "_id" : 2, "name" : "192.168.198.132:27017", "health" : 1, "state" : 7, "stateStr" : "ARBITER", "uptime" : 121, "optime" : { "t" : 0, "i" : 0 }, "optimeDate" : ISODate("1970-01-01T00:00:00Z"), "lastHeartbeat" : ISODate("2012-03-01T08:45:01Z"), "pingMs" : 1 } ], "ok" : 1 } state: 1表示当前可以进行读写&＃xff0c;2表示不能读写 health: 1表示是正常的&＃xff0c;0异常 在同一时刻&＃xff0c;每组 Replica Sets 只有一个 Primary&＃xff0c;用于接受写操作。而后会异步复制到其他成员数据库中。一旦 primary 死掉&＃xff0c;会自动投票选出接任的 primary 来&＃xff0c;原服务器恢复后成为普通成员。如果数据尚未从先前的 primary 复制到成员服务器&＃xff0c;有可能会丢失数据。 PRIMARY> db.test.insert({"name":"foobar","age":25}) PRIMARY> db.test.find() { "_id" : ObjectId("4f4f38fc47db2bfa5ceb2aee"), "name" : "foobar", "age" : 25 } SECONDARY> db.test.find() error: { "$err" : "not master and slaveok&＃61;false", "code" : 13435 } SECONDARY> db.test.insert({"name":"foobar","age":25}) not master 在主库上设置slaveok&＃61;ok PRIMARY> db.getMongo().setSlaveOk() SECONDARY> use test switched to db test SECONDARY> db.test.find() { "_id" : ObjectId("4f4f38fc47db2bfa5ceb2aee"), "name" : "foobar", "age" : 25 } 192.168.198.131上pkill mongod Thu Mar 1 17:17:51 got kill or ctrl c or hup signal 15 (Terminated), will terminate after current cmd ends Thu Mar 1 17:17:51 [interruptThread] now exiting Thu Mar 1 17:17:51 dbexit: Thu Mar 1 17:17:51 [interruptThread] shutdown: going to close listening sockets... Thu Mar 1 17:17:51 [interruptThread] closing listening socket: 7 Thu Mar 1 17:17:51 [interruptThread] closing listening socket: 8 Thu Mar 1 17:17:51 [interruptThread] closing listening socket: 9 Thu Mar 1 17:17:51 [interruptThread] removing socket file: /tmp/mongodb-27017.sock Thu Mar 1 17:17:51 [interruptThread] shutdown: going to flush diaglog... Thu Mar 1 17:17:51 [interruptThread] shutdown: going to close sockets... Thu Mar 1 17:17:51 [conn1] end connection 127.0.0.1:58614 Thu Mar 1 17:17:51 [interruptThread] shutdown: waiting for fs preallocator... Thu Mar 1 17:17:51 [interruptThread] shutdown: lock for final commit... Thu Mar 1 17:17:51 [interruptThread] shutdown: final commit... Thu Mar 1 17:17:52 [interruptThread] shutdown: closing all files... Thu Mar 1 17:17:52 [interruptThread] closeAllFiles() finished Thu Mar 1 17:17:52 [interruptThread] journalCleanup... Thu Mar 1 17:17:52 [interruptThread] removeJournalFiles Thu Mar 1 17:17:52 [interruptThread] shutdown: removing fs lock... Thu Mar 1 17:17:52 dbexit: really exiting now 192.168.198.129选择为primary Thu Mar 1 00:17:51 [conn144] end connection 192.168.198.131:35714 Thu Mar 1 00:17:51 [rsSync] replSet syncThread: 10278 dbclient error communicating with server: 192.168.198.131:27017 Thu Mar 1 00:17:52 [rsHealthPoll] DBClientCursor::init call() failed Thu Mar 1 00:17:52 [rsHealthPoll] replSet info 192.168.198.131:27017 is down (or slow to respond): DBClientBase::findN: transport error: 192.168.198.131:27017 query: { replSetHeartbeat: "myset", v: 1, pv: 1, checkEmpty: false, from: "192.168.198.129:27017" } Thu Mar 1 00:17:52 [rsHealthPoll] replSet member 192.168.198.131:27017 is now in state DOWN Thu Mar 1 00:17:52 [rsMgr] not electing self, 192.168.198.132:27017 would veto Thu Mar 1 00:17:58 [rsMgr] replSet info electSelf 1 Thu Mar 1 00:17:58 [rsMgr] replSet PRIMARY 【ARBITER】192.168.198.132日志 Thu Mar 1 04:17:51 [conn143] end connection 192.168.198.131:56260 Thu Mar 1 04:17:53 [rsHealthPoll] DBClientCursor::init call() failed Thu Mar 1 04:17:53 [rsHealthPoll] replSet info 192.168.198.131:27017 is down (or slow to respond): DBClientBase::findN: transport error: 192.168.198.131:27017 query: { replSetHeartbeat: "myset", v: 1, pv: 1, checkEmpty: false, from: "192.168.198.132:27017" } Thu Mar 1 04:17:53 [rsHealthPoll] replSet member 192.168.198.131:27017 is now in state DOWN Thu Mar 1 04:17:58 [conn144] replSet info voting yea for 192.168.198.129:27017 (1) Thu Mar 1 04:17:59 [rsHealthPoll] replSet member 192.168.198.129:27017 is now in state PRIMARY Thu Mar 1 04:18:05 [rsHealthPoll] couldn&＃39;t connect to 192.168.198.131:27017: couldn&＃39;t connect to server 192.168.198.131:27017 PRIMARY> rs.status(); { "set" : "myset", "date" : ISODate("2012-03-01T09:20:37Z"), "myState" : 1, "syncingTo" : "192.168.198.131:27017", "members" : [ { "_id" : 0, "name" : "192.168.198.131:27017", "health" : 0, "state" : 8, "stateStr" : "(not reachable/healthy)", "uptime" : 0, "optime" : { "t" : 1330591997000, "i" : 1 }, "optimeDate" : ISODate("2012-03-01T08:53:17Z"), "lastHeartbeat" : ISODate("2012-03-01T09:17:50Z"), "pingMs" : 0, "errmsg" : "socket exception" }, { "_id" : 1, "name" : "192.168.198.129:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "optime" : { "t" : 1330591997000, "i" : 1 }, "optimeDate" : ISODate("2012-03-01T08:53:17Z"), "self" : true }, { "_id" : 2, "name" : "192.168.198.132:27017", "health" : 1, "state" : 7, "stateStr" : "ARBITER", "uptime" : 2244, "optime" : { "t" : 0, "i" : 0 }, "optimeDate" : ISODate("1970-01-01T00:00:00Z"), "lastHeartbeat" : ISODate("2012-03-01T09:20:36Z"), "pingMs" : 0 } ], "ok" : 1 } PRIMARY> db.test.find() { "_id" : ObjectId("4f4f38fc47db2bfa5ceb2aee"), "name" : "foobar", "age" : 25 } { "_id" : ObjectId("4f4f3fe2a7c9a9d1eb78392f"), "name" : "ttlsa", "age" : 1 } 再次启动192.168.198.131的mongod服务 Thu Mar 1 17:23:24 [initandlisten] MongoDB starting : pid&＃61;6977 port&＃61;27017 dbpath&＃61;/data/mongodb/myset 64-bit host&＃61;node2 Thu Mar 1 17:23:24 [initandlisten] db version v2.0.3, pdfile version 4.5 Thu Mar 1 17:23:24 [initandlisten] git version: 05bb8aa793660af8fce7e36b510ad48c27439697 Thu Mar 1 17:23:24 [initandlisten] build info: Linux ip-10-110-9-236 2.6.21.7-2.ec2.v1.2.fc8xen #1 SMP Fri Nov 20 17:48:28 EST 2009 x86_64 BOOST_LIB_VERSION&＃61;1_41 Thu Mar 1 17:23:24 [initandlisten] options: { dbpath: "/data/mongodb/myset", fork: true, logappend: true, logpath: "/data/mongodb/myset/myset.log", oplogSize: 100, replSet: "myset" } Thu Mar 1 17:23:24 [initandlisten] journal dir&＃61;/data/mongodb/myset/journal Thu Mar 1 17:23:24 [initandlisten] recover : no journal files present, no recovery needed Thu Mar 1 17:23:26 [initandlisten] waiting for connections on port 27017 Thu Mar 1 17:23:26 [websvr] admin web console waiting for connections on port 28017 Thu Mar 1 17:23:27 [initandlisten] connection accepted from 192.168.198.129:43753 #1 Thu Mar 1 17:23:27 [initandlisten] connection accepted from 127.0.0.1:37253 #2 Thu Mar 1 17:23:27 [rsStart] trying to contact 192.168.198.129:27017 Thu Mar 1 17:23:27 [rsStart] replSet STARTUP2 Thu Mar 1 17:23:27 [rsSync] replSet SECONDARY SECONDARY> use test switched to db test SECONDARY> db.test.find() { "_id" : ObjectId("4f4f38fc47db2bfa5ceb2aee"), "name" : "foobar", "age" : 25 } { "_id" : ObjectId("4f4f3fe2a7c9a9d1eb78392f"), "name" : "ttlsa", "age" : 1 }