centos7部署MongoDB数据库复制集（超详细）
centos7部署MongoDB数据库复制集（超详细）重点：复制集概述；复制集实现原理；复制集的应用案例；
一、概述：
组成：
Mongodb复制集（副本集replica set）由一组Mongod实例（进程）组成，包含一个Primary节点和多个Secondary节点，Mongodb Driver（客户端）的所有数据都写入Primary，Secondary通过oplog来同步Primary的数据，保证主节点和从节点数据的一致性，复制集在完成主从复制的基础上，通过心跳机制，一旦primary节点出现宕机，则触发选举一个新的主节点，剩下的secondary节点指向新的primary，时间应该在10-30s内完成感知primary节点故障，实现高可用数据库集群；
特点：
主是唯一的，但不是固定的；
由大多数据原则保证数据的一致性；
从库无法写入（默认情况下，不使用驱动连接时，也是不能查询的）；
相对于传统的主从结构，复制集可以自动容灾；
二、原理：
角色（按是否存储数据划分）：
Primary：主节点，由选举产生，负责客户端的写操作，产生oplog日志文件；
Secondary：从节点，负责客户端的读操作，提供数据的备份和故障的切换；
Arbiter：仲裁节点，只参与选举的投票，不会成为primary，也不向Primary同步数据，若部署了一个2个节点的复制集，1个Primary，1个Secondary，任意节点宕机，复制集将不能提供服务了（无法选出Primary），这时可以给复制集添加一个Arbiter节点，即使有节点宕机，仍能选出Primary；
角色（按类型区分）：
Standard（标准）：这种是常规节点，它存储一份完整的数据副本，参与投票选举，有可能成为主节点；
Passive（被动）：存储完整的数据副本，参与投票，不能成为活跃节点。
Arbiter（投票）：仲裁节点只参与投票，不接收复制的数据，也不能成为活跃节点。
注：每个参与节点（非仲裁者）有个优先权（0-1000），优先权（priority）为0则是被动的，不能成为活跃节点，优先权不为0的，按照由大到小选出活跃节点，优先值一样的则看谁的数据比较新；
注：Mongodb 3.0里，复制集成员最多50个，参与Primary选举投票的成员最多7个；
选举：
每个节点通过优先级定义出节点的类型（标准、被动、投票）；
标准节点通过对比自身数据进行选举出peimary节点或者secondary节点；
影响选举的因素：
1.心跳检测：复制集内成员每隔两秒向其他成员发送心跳检测信息，若10秒内无响应，则标记其为不可用；
2.连接：在多个节点中，最少保证两个节点为活跃状态，如果集群中共三个节点，挂掉两个节点，那么剩余的节点无论状态是primary还是处于选举过程中，都会直接被降权为secondary；
触发选举的情况：
1.初始化状态2.从节点们无法与主节点进行通信 3.主节点辞职
主节点辞职的情况：
1.在接收到replSetStepDown命令后；
2.在现有的环境中，其他secondary节点的数据落后于本身10s内，且拥有更高优先级；
3.当主节点无法与群集中多数节点通信；
注：当主节点辞职后，主节点将关闭自身所有的连接，避免出现客户端在从节点进行写入操作；
三、应用案例：
异常处理：
当Primary宕机时，如果有数据未同步到Secondary，当Primary重新加入时，如果新的Primary上已经发生了写操作，则旧Primary需要回滚部分操作，以保证数据集与新的Primary一致。旧Primary将回滚的数据写到单独的rollback目录下，数据库管理员可根据需要使用mongorestore进行恢复。
环境：
系统主机名 IP地址 软件
Centos 7.4mongodb.benet.com 192.168.100.101 mongodb-linux-x86_64-rhel70-3.6.3.tgz
实验步骤：
1.安装mongodb；
2.创建并启动四个实例；
3.配置实例；
4.创建复制集并添加节点；
5.模拟Primary节点出现故障，查看角色切换情况；
6.手动切换Primary角色；
7.指定节点的优先级，验证角色重选情况；
8.将标准节点统统停掉，被动节点也不会成为主节点；
9.查询复制集状态以及查看oplog日志文件的大小；
[*]部署用户认证登录（密钥对）的复制集；
安装mongodb；
下载mongodb软件包；
# tar zxvf mongodb-linux-x86_64-rhel70-3.6.3.tgz
# mv mongodb-linux-x86_64-rhel70-3.6.3 /usr/local/mongodb
# echo "export PATH=/usr/local/mongodb/bin:\$PATH" >>/etc/profile
# source /etc/profile
# ulimit -n 25000
# ulimit -u 25000
# echo 0 >/proc/sys/vm/zone_reclaim_mode
# sysctl -w vm.zone_reclaim_mode=0
# echo never >/sys/kernel/mm/transparent_hugepage/enabled
# echo never >/sys/kernel/mm/transparent_hugepage/defrag
创建并启动四个实例；
# cd /usr/local/mongodb/bin/
# mkdir {../mongodb1,../mongodb2,../mongodb3,../mongodb4}
# mkdir ../logs
# touch ../logs/mongodb{1..4}.log
# chmod 777 ../logs/mongodb
# cat /usr/local/mongodb/bin/mongodb1.conf
bind_ip=192.168.100.101
port=27017
dbpath=/usr/local/mongodb/mongodb1/
logpath=/usr/local/mongodb/logs/mongodb1.log
logappend=true
fork=true
maxConns=5000
replSet=haha
#replication name
END
# cat /usr/local/mongodb/bin/mongodb2.conf
bind_ip=192.168.100.101
port=27018
dbpath=/usr/local/mongodb/mongodb2/
logpath=/usr/local/mongodb/logs/mongodb2.log
logappend=true
fork=true
maxConns=5000
replSet=haha
END
# cat /usr/local/mongodb/bin/mongodb3.conf
bind_ip=192.168.100.101
port=27019
dbpath=/usr/local/mongodb/mongodb3/
logpath=/usr/local/mongodb/logs/mongodb3.log
logappend=true
fork=true
maxConns=5000
replSet=haha
END
# cat /usr/local/mongodb/bin/mongodb4.conf
bind_ip=192.168.100.101
port=27020
dbpath=/usr/local/mongodb/mongodb4/
logpath=/usr/local/mongodb/logs/mongodb4.log
logappend=true
fork=true
maxConns=5000
replSet=haha
END
# cd
# mongod -f/usr/local/mongodb/bin/mongodb1.conf
# mongod -f/usr/local/mongodb/bin/mongodb2.conf
# mongod -f/usr/local/mongodb/bin/mongodb3.conf
# mongod -f/usr/local/mongodb/bin/mongodb4.conf
# netstat -utpln |grep mongod
tcp 0 0 192.168.100.101:27019 0.0.0.0: LISTEN 2271/mongod
tcp 0 0 192.168.100.101:27020 0.0.0.0: LISTEN 15260/mongod
tcp 0 0 192.168.100.101:27017 0.0.0.0: LISTEN 2440/mongod
tcp 0 0 192.168.100.101:27018 0.0.0.0:* LISTEN 1412/mongod
# echo -e "/usr/local/mongodb/bin/mongod -f/usr/local/mongodb/bin/mongodb1.conf \n/usr/local/mongodb/bin/mongod -f/usr/local/mongodb/bin/mongodb2.conf\n/usr/local/mongodb/bin/mongod -f/usr/local/mongodb/bin/mongodb3.conf\n/usr/local/mongodb/bin/mongod -f/usr/local/mongodb/bin/mongodb4.conf">>/etc/rc.local
# chmod +x /etc/rc.local
# cat /etc/init.d/mongodb
#!/bin/bash
INSTANCE=\$1
ACTION=\$2
case "\$ACTION" in
'start')
/usr/local/mongodb/bin/mongod -f /usr/local/mongodb/bin/"\$INSTANCE".conf;;
'stop')
/usr/local/mongodb/bin/mongod -f /usr/local/mongodb/bin/"\$INSTANCE".conf --shutdown;;
'restart')
/usr/local/mongodb/bin/mongod -f /usr/local/mongodb/bin/"\$INSTANCE".conf --shutdown
/usr/local/mongodb/bin/mongod -f /usr/local/mongodb/bin/"\$INSTANCE".conf;;
esac
END
# chmod +x /etc/init.d/mongodb
# /etc/init.d/mongodb mongodb1 stop
killing process with pid: 1301
# /etc/init.d/mongodb mongodb1 start
about to fork child process, waiting until server is ready for connections.
forked process: 1457
child process started successfully, parent exiting
# mongo --port 27017 --host 192.168.100.101
配置实例；
# mongo --port 27017 --host 192.168.100.101
show dbs
2018-04-19T04:34:35.871+0800 E QUERY Error: listDatabases failed:{
"ok" : 0,
"errmsg" : "not master and slaveOk=false",
"code" : 13435,
"codeName" : "NotMasterNoSlaveOk"
} :_getErrorWithCode@src/mongo/shell/utils.js:25:13br/>shellHelper.show@src/mongo/shell/utils.js:816:19
shellHelper@src/mongo/shell/utils.js:706:15@(shellhelp2):1:1br/>_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:65:1shellHelper.show@src/mongo/shell/utils.js:816:19br/>@(shellhelp2):1:1
exit
创建复制集并添加节点；
# mongo --port 27017 --host 192.168.100.101
cfg={"_id":"haha","members":[{"_id":0,"host":"192.168.100.101:27017"},{"_id":1,"host":"192.168.100.101:27018"},{"_id":2,"host":"192.168.100.101:27019"}]} ##添加节点
{
"_id" : "haha",
"members" : [
{
"_id" : 0,
"host" : "192.168.100.101:27017"
},
{
"_id" : 1,
"host" : "192.168.100.101:27018"
},
{
"_id" : 2,
"host" : "192.168.100.101:27019"
}
]
}
rs.initiate(cfg) ##初始化节点
{
"ok" : 1,
"operationTime" : Timestamp(1524083843, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1524083843, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
haha:OTHER>
haha:PRIMARY>
haha:PRIMARY> rs.status()
{
"set" : "haha",
"date" : ISODate("2018-04-18T20:37:54.095Z"),
"myState" : 1,
"term" : NumberLong(1),
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"appliedOpTime" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"durableOpTime" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
}
},
"members" : [
{
"_id" : 0,
"name" : "192.168.100.101:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 329,
"optime" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:37:35Z"),
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1524083854, 1),
"electionDate" : ISODate("2018-04-18T20:37:34Z"),
"configVersion" : 1,
"self" : true
},
{
"_id" : 1,
"name" : "192.168.100.101:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 30,
"optime" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:37:35Z"),
"optimeDurableDate" : ISODate("2018-04-18T20:37:35Z"),
"lastHeartbeat" : ISODate("2018-04-18T20:37:54.043Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:37:52.499Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "192.168.100.101:27017",
"configVersion" : 1
},
{
"_id" : 2,
"name" : "192.168.100.101:27019",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 30,
"optime" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1524083855, 5),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:37:35Z"),
"optimeDurableDate" : ISODate("2018-04-18T20:37:35Z"),
"lastHeartbeat" : ISODate("2018-04-18T20:37:54.043Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:37:52.500Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "192.168.100.101:27017",
"configVersion" : 1
}
],
"ok" : 1,
"operationTime" : Timestamp(1524083855, 5),
"$clusterTime" : {
"clusterTime" : Timestamp(1524083855, 5),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
haha:PRIMARY> rs.addArb("192.168.100.101:27020") ##添加仲裁节点
{
"ok" : 1,
"operationTime" : Timestamp(1524083905, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1524083905, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
haha:PRIMARY> rs.status()
{
"set" : "haha",
"date" : ISODate("2018-04-18T20:38:41.468Z"),
"myState" : 1,
"term" : NumberLong(1),
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1524083915, 1),
"t" : NumberLong(1)
},
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1524083915, 1),
"t" : NumberLong(1)
},
"appliedOpTime" : {
"ts" : Timestamp(1524083915, 1),
"t" : NumberLong(1)
},
"durableOpTime" : {
"ts" : Timestamp(1524083915, 1),
"t" : NumberLong(1)
}
},
"members" : [
{
"_id" : 0,
"name" : "192.168.100.101:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 376,
"optime" : {
"ts" : Timestamp(1524083915, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:38:35Z"),
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1524083854, 1),
"electionDate" : ISODate("2018-04-18T20:37:34Z"),
"configVersion" : 2,
"self" : true
},
{
"_id" : 1,
"name" : "192.168.100.101:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 78,
"optime" : {
"ts" : Timestamp(1524083905, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1524083905, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:38:25Z"),
"optimeDurableDate" : ISODate("2018-04-18T20:38:25Z"),
"lastHeartbeat" : ISODate("2018-04-18T20:38:41.134Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:38:40.134Z"),
"pingMs" : NumberLong(0),
"configVersion" : 2
},
{
"_id" : 2,
"name" : "192.168.100.101:27019",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 78,
"optime" : {
"ts" : Timestamp(1524083905, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1524083905, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:38:25Z"),
"optimeDurableDate" : ISODate("2018-04-18T20:38:25Z"),
"lastHeartbeat" : ISODate("2018-04-18T20:38:41.134Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:38:40.136Z"),
"pingMs" : NumberLong(0),
"configVersion" : 2
},
{
"_id" : 3,
"name" : "192.168.100.101:27020",
"health" : 1,
"state" : 7,
"stateStr" : "ARBITER",
"uptime" : 16,
"lastHeartbeat" : ISODate("2018-04-18T20:38:41.137Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:38:40.140Z"),
"pingMs" : NumberLong(0),
"configVersion" : 2
}
],
"ok" : 1,
"operationTime" : Timestamp(1524083915, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1524083915, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
注：rs.add()和rs.remove()命令分别用于添加和删除标准节点
haha:PRIMARY> show dbs
admin 0.000GB
config0.000GB
local 0.000GB
haha:PRIMARY> use cloud
switched to db cloud
haha:PRIMARY> db.users.insert({"id":"1","name":"xiaoming"})
WriteResult({ "nInserted" : 1 })
haha:PRIMARY> db.users.find()
{ "_id" : ObjectId("5ad7b245f6308759d4605b5c"), "id" : "1", "name" : "xiaoming" }
haha:PRIMARY> show dbs
admin 0.000GB
cloud 0.000GB
config0.000GB
local 0.000GB
haha:PRIMARY> exit
# mongo --port 27018 --host 192.168.100.101
haha:SECONDARY> rs.status()
{
"set" : "haha",
"date" : ISODate("2018-04-18T20:50:50.975Z"),
"myState" : 2,
"term" : NumberLong(1),
"syncingTo" : "192.168.100.101:27017",
"heartbeatIntervalMillis" : NumberLong(2000),
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"appliedOpTime" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"durableOpTime" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
}
},
"members" : [
{
"_id" : 0,
"name" : "192.168.100.101:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 805,
"optime" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:50:45Z"),
"optimeDurableDate" : ISODate("2018-04-18T20:50:45Z"),
"lastHeartbeat" : ISODate("2018-04-18T20:50:49.966Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:50:49.997Z"),
"pingMs" : NumberLong(0),
"electionTime" : Timestamp(1524083854, 1),
"electionDate" : ISODate("2018-04-18T20:37:34Z"),
"configVersion" : 2
},
{
"_id" : 1,
"name" : "192.168.100.101:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 1497,
"optime" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:50:45Z"),
"syncingTo" : "192.168.100.101:27017",
"configVersion" : 2,
"self" : true
},
{
"_id" : 2,
"name" : "192.168.100.101:27019",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 805,
"optime" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"optimeDurable" : {
"ts" : Timestamp(1524084645, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2018-04-18T20:50:45Z"),
"optimeDurableDate" : ISODate("2018-04-18T20:50:45Z"),
"lastHeartbeat" : ISODate("2018-04-18T20:50:49.811Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:50:49.965Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "192.168.100.101:27017",
"configVersion" : 2
},
{
"_id" : 3,
"name" : "192.168.100.101:27020",
"health" : 1,
"state" : 7,
"stateStr" : "ARBITER",
"uptime" : 745,
"lastHeartbeat" : ISODate("2018-04-18T20:50:49.966Z"),
"lastHeartbeatRecv" : ISODate("2018-04-18T20:50:50.378Z"),
"pingMs" : NumberLong(0),
"configVersion" : 2
}
],
"ok" : 1,
"operationTime" : Timestamp(1524084645, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1524084645, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
haha:SECONDARY> show dbs ##secondary节点默认无法读取，可以通过以下方式或者驱动方式实现
2018-04-19T04:52:42.813+0800 E QUERY Error: listDatabases failed:{
"operationTime" : Timestamp(1524084755, 1),
"ok" : 0,
"errmsg" : "not master and slaveOk=false",
"code" : 13435,
"codeName" : "NotMasterNoSlaveOk",
"$clusterTime" : {
"clusterTime" : Timestamp(1524084755, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
} :_getErrorWithCode@src/mongo/shell/utils.js:25:13br/>shellHelper.show@src/mongo/shell/utils.js:816:19
shellHelper@src/mongo/shell/utils.js:706:15@(shellhelp2):1:1
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