MongoDB复制集是一个带有故障转移的主从集群。是从现有的主从模式演变而来,增加了自动故障转移和节点成员自动恢复。 MongoDB复制集模式中没有固定的主结点,在启动后,多个服务节点间将自动选举产生一个主结点。该主结点被称为primary,一个或多个从结点被称为secondaries。 primary结点基本上就是master结点,不同之处在于primary结点在不同时间可能是不同的服务器。如果当前的主结点失效了,复制集中的其余结点将会试图选出一个 新的主结点。
MongoDB复制集模式的好处:
在一个MongoDB复制集集群中,各个服务器有以下几种状态:
如上介绍所知,mongodb中的复制可以在多台服务器中同步数据。复制提供了冗余和增加了数据的高可用性,防止单个节点易丢失数据的可能性,也可以用来进行读写分离提高客户端操作性能。复制集中各节点的mongodb实例有相同的数据集副本。主节点可以接收客户端所有写操作记录到日志中,从库复制主库的操作日志记录应用到其数据库中。一个客户端只能有一个主节点,如果主节点不可用(10秒内无法连接),复制集中将选一个成员节点作为主节点。
mongodb主备+仲裁的基本结构如下:
下面简单介绍下MongoDB 副本集的部署过程:
1)服务器信息
sign-mongo01.wangshibo.cn 172.16.51.216 Primary
sign-mongo02.wangshibo.cn 172.16.51.217 Secondary
sign-mongo03.wangshibo.cn 172.16.51.218 Arbiter
三台服务器均设置好主机名,关闭iptables及selinux(略)
2)在3台服务器文件hosts文件中都添加以下3行:
[root@sign-mongo01 ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
172.16.51.216 sign-mongo01.wangshibo.cn
172.16.51.217 sign-mongo02.wangshibo.cn
172.16.51.218 sign-mongo03.wangshibo.cn
3)安装部署mongodb(三台机器都安装)
下载地址:https://www.mongodb.org/dl/linux/x86_64-rhel62
[app@sign-mongo01 software]$ pwd
/data/software
[app@sign-mongo01 software]$ ls
mongodb-linux-x86_64-rhel62-v3.2-latest.tgz
[app@sign-mongo01 software]$ tar -zvxf mongodb-linux-x86_64-rhel62-v3.2-latest.tgz
[app@sign-mongo01 software]$ mv mongodb-linux-x86_64-rhel62-3.2.17-34-g4c1bae566c /data/mongodb
[app@sign-mongo01 software]$ cd /data/mongodb/
[app@sign-mongo01 mongodb]$ mkdir data
[app@sign-mongo01 mongodb]$ mkdir log
[app@sign-mongo01 mongodb]$ vim mongodb.conf
pidfilepath=/data/mongodb/log/mongod.pid
logpath=/data/mongodb/log/mongod.log
dbpath=/data/mongodb
logappend=true
bind_ip=172.16.51.216
port=27017
fork=true
replSet=rs0
备节点的mongodb.conf配置文件分别为:
[app@sign-mongo02 mongodb]$ vim mongodb.conf
pidfilepath=/data/mongodb/log/mongod.pid
logpath=/data/mongodb/log/mongod.log
dbpath=/data/mongodb
logappend=true
bind_ip=172.16.51.217
port=27018
fork=true
replSet=rs0
其中:replSet=rs0 #表示复制集名称:rs0
启动主备服务器的mongodb
[app@sign-mongo01 ~]$ /data/mongodb/bin/mongod --config /data/mongodb/mongodb.conf
about to fork child process, waiting until server is ready for connections.
forked process: 7317
child process started successfully, parent exiting
[app@sign-mongo01 mongodb]$ ps -ef|grep mongodb
app 7317 1 0 21:38 ? 00:00:00 /data/mongodb/bin/mongod --config /data/mongodb/mongodb.conf
app 7342 7254 0 21:38 pts/1 00:00:00 grep mongodb
[app@sign-mongo01 mongodb]$ lsof -i:27017
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mongod 7317 app 6u IPv4 27011 0t0 TCP sign-mongo01.wangshibo.cn:27017 (LISTEN)
[app@sign-mongo02 mongodb]$ /data/mongodb/bin/mongod --config /data/mongodb/mongodb.conf
about to fork child process, waiting until server is ready for connections.
forked process: 9725
child process started successfully, parent exiting
[app@sign-mongo02 mongodb]$ lsof -i:27018
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mongod 9725 app 6u IPv4 27191 0t0 TCP sign-mongo02.wangshibo.cn:27018 (LISTEN)
设置mongodb的环变量
[root@sign-mongo01 src]# vim /etc/profile
......
export PATH=$PATH:/data/mongodb/bin
[root@sign-mongo01 src]# source /etc/profile
登录到mongodb中:
[app@sign-mongo01 ~]$ mongo 172.16.51.216:27017
MongoDB shell version: 3.2.17-34-g4c1bae566c
connecting to: 172.16.51.216:27017/test
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
http://docs.mongodb.org/
Questions? Try the support group
http://groups.google.com/group/mongodb-user
Server has startup warnings:
2017-11-22T21:38:18.063+0800 I CONTROL [initandlisten]
2017-11-22T21:38:18.063+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-11-22T21:38:18.063+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:38:18.063+0800 I CONTROL [initandlisten]
2017-11-22T21:38:18.063+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-11-22T21:38:18.063+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:38:18.063+0800 I CONTROL [initandlisten]
>
初始化复制集:(集合为:"rs0" ;第一个成员为:"sign-mongo01.wangshibo.cn:27017"
> rs.initiate({_id: "rs0",members: [{ _id: 0 , host: "sign-mongo01.wangshibo.cn:27017" }]})
{ "ok" : 1 }
rs0:OTHER> //接着回车,显示这个节点为Primary主节点
rs0:PRIMARY>
接着添加另1个成员:
rs0:PRIMARY> rs.add("sign-mongo02.wangshibo.cn:27018")
{ "ok" : 1 }
查看成员信息 (或者使用 db.isMaster() )
rs0:PRIMARY> rs.status()
{
"set" : "rs0",
"date" : ISODate("2017-11-22T13:55:28.446Z"),
"myState" : 1,
"term" : NumberLong(1),
"heartbeatIntervalMillis" : NumberLong(2000),
"members" : [
{
"_id" : 0,
"name" : "sign-mongo01.wangshibo.cn:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 1031,
"optime" : {
"ts" : Timestamp(1511358895, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2017-11-22T13:54:55Z"),
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1511358843, 2),
"electionDate" : ISODate("2017-11-22T13:54:03Z"),
"configVersion" : 2,
"self" : true
},
{
"_id" : 1,
"name" : "sign-mongo02.wangshibo.cn:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 32,
"optime" : {
"ts" : Timestamp(1511358895, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2017-11-22T13:54:55Z"),
"lastHeartbeat" : ISODate("2017-11-22T13:55:27.684Z"),
"lastHeartbeatRecv" : ISODate("2017-11-22T13:55:27.827Z"),
"pingMs" : NumberLong(0),
"configVersion" : 2
}
],
"ok" : 1
}
或者使用该方法查看,结果也是一样:
rs0:PRIMARY> use admin
switched to db admin
rs0:PRIMARY> db.runCommand( { replSetGetStatus : 1 } )
{
"set" : "rs0",
"date" : ISODate("2017-11-23T01:12:20.701Z"),
"myState" : 1,
"term" : NumberLong(1),
"heartbeatIntervalMillis" : NumberLong(2000),
"members" : [
{
"_id" : 0,
"name" : "sign-mongo01.wangshibo.cn:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 41643,
"optime" : {
"ts" : Timestamp(1511358895, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2017-11-22T13:54:55Z"),
"electionTime" : Timestamp(1511358843, 2),
"electionDate" : ISODate("2017-11-22T13:54:03Z"),
"configVersion" : 2,
"self" : true
},
{
"_id" : 1,
"name" : "sign-mongo02.wangshibo.cn:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 40645,
"optime" : {
"ts" : Timestamp(1511358895, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2017-11-22T13:54:55Z"),
"lastHeartbeat" : ISODate("2017-11-23T01:12:19.418Z"),
"lastHeartbeatRecv" : ISODate("2017-11-23T01:12:16.225Z"),
"pingMs" : NumberLong(0),
"configVersion" : 2
}
],
"ok" : 1
}
rs0:PRIMARY>
详细说明如下:
"_id" : #集群中节点编号
"name" : #成员服务器名称及端口
"health" : #表示成员中的健康状态(0:down;1:up)
"state" : #为0~10,表示成员的当前状态
"stateStr" : #描述该成员是主库(PRIMARY)还是备库(SECONDARY)
"uptime" : #该成员在线时间(秒)
"optime" : #成员最后一次应用日志(oplog)的信息
"optimeDate" : #成员最后一次应用日志(oplog)的时间
"electionTime" : #当前primary从操作日志中选举信息
"electionDate" : #当前primary被选定为primary的日期
"configVersion" : #mongodb版本
"self" : #为true 表示当前节点
4)测试操作。在主库中,可以任意操作:
rs0:PRIMARY> show dbs
local 0.000GB
rs0:PRIMARY> use mydb //切换到要创建的数据库
switched to db mydb
rs0:PRIMARY> show dbs //use只是转到相关数据库,此时并没有做任何操作,所以并不会创建相应的数据库,只有当真正的操作了一次数据库就会自动创建。
local 0.000GB
rs0:PRIMARY> db.stats();
{
"db" : "mydb",
"collections" : 0,
"objects" : 0,
"avgObjSize" : 0,
"dataSize" : 0,
"storageSize" : 0,
"numExtents" : 0,
"indexes" : 0,
"indexSize" : 0,
"fileSize" : 0,
"ok" : 1
}
rs0:PRIMARY> db.coll.insert({"id":1})
WriteResult({ "nInserted" : 1 })
rs0:PRIMARY> db.coll.find()
{ "_id" : ObjectId("5a162222991b83743942d169"), "id" : 1 }
rs0:PRIMARY> db.coll.remove({"id":1})
WriteResult({ "nRemoved" : 1 })
rs0:PRIMARY> show dbs
local 0.000GB
mydb 0.000GB
现在到备库中
172.16.51.217 (sign-mongo02.wangshibo.cn )
查看分库数据库目录,发现多了数据库,数据库与主库(172.16.51.216)一致!是主库同步过来的。
[app@sign-mongo02 ~]$ mongo 172.16.51.217:27018
MongoDB shell version: 3.2.17-34-g4c1bae566c
connecting to: 172.16.51.217:27018/test
Server has startup warnings:
2017-11-22T21:46:38.417+0800 I CONTROL [initandlisten]
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten]
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten]
在副本服务器中登录其本地数据库,发现可以连接,但是无法读写操作:
rs0:SECONDARY> show dbs
2017-11-23T09:25:35.961+0800 E QUERY [thread1] Error: listDatabases failed:{ "ok" : 0, "errmsg" : "not master and slaveOk=false", "code" : 13435 } :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
Mongo.prototype.getDBs@src/mongo/shell/mongo.js:62:1
shellHelper.show@src/mongo/shell/utils.js:781:19
shellHelper@src/mongo/shell/utils.js:671:15
@(shellhelp2):1:1
rs0:SECONDARY>
从库开启读操作(此时可以测试主库插入,从库查看,同步正常):
rs0:SECONDARY> rs.slaveOk();
rs0:SECONDARY> show dbs
local 0.000GB
mydb 0.000GB
5)现在模拟主库不可用,将主节点服务停止:
[app@sign-mongo01 mongodb]$ pkill -9 mongod
[app@sign-mongo01 mongodb]$ ps -ef|grep mongodb
app 9524 9398 0 09:32 pts/0 00:00:00 grep mongodb
到备节点172.16.51.217 中登录mongodb,查看复制集状态:
[app@sign-mongo02 ~]$ mongo 172.16.51.217:27018
MongoDB shell version: 3.2.17-34-g4c1bae566c
connecting to: 172.16.51.217:27018/test
Server has startup warnings:
2017-11-22T21:46:38.417+0800 I CONTROL [initandlisten]
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten]
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten]
rs0:SECONDARY> rs.status()
{
"set" : "rs0",
"date" : ISODate("2017-11-23T01:33:29.688Z"),
"myState" : 2,
"term" : NumberLong(1),
"heartbeatIntervalMillis" : NumberLong(2000),
"members" : [
{
"_id" : 0,
"name" : "sign-mongo01.wangshibo.cn:27017",
"health" : 0,
"state" : 8,
"stateStr" : "(not reachable/healthy)",
"uptime" : 0,
"optime" : {
"ts" : Timestamp(0, 0),
"t" : NumberLong(-1)
},
"optimeDate" : ISODate("1970-01-01T00:00:00Z"),
"lastHeartbeat" : ISODate("2017-11-23T01:33:28.732Z"),
"lastHeartbeatRecv" : ISODate("2017-11-23T01:32:28.099Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "Connection refused",
"configVersion" : -1
},
{
"_id" : 1,
"name" : "sign-mongo02.wangshibo.cn:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 42412,
"optime" : {
"ts" : Timestamp(1511399985, 1),
"t" : NumberLong(1)
},
"optimeDate" : ISODate("2017-11-23T01:19:45Z"),
"infoMessage" : "could not find member to sync from",
"configVersion" : 2,
"self" : true
}
],
"ok" : 1
}
有上面可看出,主节点删除服务进程,primary并没有切换到备节点上:
再次启动主节点的mongodb服务,发现primary才自动切换回到主节点:
[app@sign-mongo01 mongodb]$ nohup /data/mongodb/bin/mongod --config /data/mongodb/mongodb.conf
nohup: ignoring input and appending output to `nohup.out'
[app@sign-mongo01 mongodb]$ ps -ef|grep mongodb
app 9538 1 8 09:37 ? 00:00:00 /data/mongodb/bin/mongod --config /data/mongodb/mongodb.conf
app 9610 9398 0 09:37 pts/0 00:00:00 grep mongodb
[app@sign-mongo01 mongodb]$ mongo 172.16.51.216:27017
MongoDB shell version: 3.2.17-34-g4c1bae566c
connecting to: 172.16.51.216:27017/test
Server has startup warnings:
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten]
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten]
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten]
rs0:PRIMARY> rs.status()
{
"set" : "rs0",
"date" : ISODate("2017-11-23T01:38:19.631Z"),
"myState" : 1,
"term" : NumberLong(2),
"heartbeatIntervalMillis" : NumberLong(2000),
"members" : [
{
"_id" : 0,
"name" : "sign-mongo01.wangshibo.cn:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 54,
"optime" : {
"ts" : Timestamp(1511401058, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2017-11-23T01:37:38Z"),
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1511401058, 1),
"electionDate" : ISODate("2017-11-23T01:37:38Z"),
"configVersion" : 2,
"self" : true
},
{
"_id" : 1,
"name" : "sign-mongo02.wangshibo.cn:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 53,
"optime" : {
"ts" : Timestamp(1511401058, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2017-11-23T01:37:38Z"),
"lastHeartbeat" : ISODate("2017-11-23T01:38:18.072Z"),
"lastHeartbeatRecv" : ISODate("2017-11-23T01:38:18.596Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "sign-mongo01.wangshibo.cn:27017",
"configVersion" : 2
}
],
"ok" : 1
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
现在开始部署仲裁节点sign-mongo03.wangshibo.cn
[app@sign-mongo03 ~]$ mkdir /data/mongodb/arbiter
[app@sign-mongo03 ~]$ ll -d /data/mongodb/arbiter
drwxrwxr-x 2 app app 4096 Nov 23 09:39 /data/mongodb/arbiter
本案例是在普通用户app账号下部署的,权限都是app.app。
如果是在root账号下部署,那么需要将mongodb数据目录下的文件全部设置mongodb.mongodb权限
mongodb.conf配置:
[app@sign-mongo03 ~]$ vim /data/mongodb/mongodb.conf
pidfilepath=/data/mongodb/log/mongod.pid
logpath=/data/mongodb/log/mongod.log
dbpath=/data/mongodb/arbiter
logappend=false
bind_ip=172.16.51.218
port=27019
fork=true
replSet=rs0
接着重启服务:
[app@sign-mongo03 ~]$ /data/mongodb/bin/mongod --config /data/mongodb/mongodb.conf
about to fork child process, waiting until server is ready for connections.
forked process: 9217
child process started successfully, parent exiting
[app@sign-mongo03 ~]$ ps -ef|grep mongo
app 9217 1 1 09:46 ? 00:00:00 /data/mongodb/bin/mongod --config /data/mongodb/mongodb.conf
app 9242 9158 0 09:46 pts/0 00:00:00 grep mongo
[app@sign-mongo03 ~]$ lsof -i:27019
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mongod 9217 app 6u IPv4 37321 0t0 TCP sign-mongo03.wangshibo.cn:27019 (LISTEN)
然后在Paimary主节点sign-mongo01.wangshibo.cn的mongodb中添加仲裁节点并查看结果
[app@sign-mongo01 mongodb]$ mongo 172.16.51.216:27017
MongoDB shell version: 3.2.17-34-g4c1bae566c
connecting to: 172.16.51.216:27017/test
Server has startup warnings:
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten]
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten]
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-23T09:37:26.467+0800 I CONTROL [initandlisten]
rs0:PRIMARY> rs.addArb("sign-mongo03.wangshibo.cn:27019")
{ "ok" : 1 }
rs0:PRIMARY> db.isMaster()
{
"hosts" : [
"sign-mongo01.wangshibo.cn:27017",
"sign-mongo02.wangshibo.cn:27018"
],
"arbiters" : [
"sign-mongo03.wangshibo.cn:27019"
],
"setName" : "rs0",
"setVersion" : 4,
"ismaster" : true,
"secondary" : false,
"primary" : "sign-mongo01.wangshibo.cn:27017",
"me" : "sign-mongo01.wangshibo.cn:27017",
"electionId" : ObjectId("7fffffff0000000000000003"),
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 1000,
"localTime" : ISODate("2017-11-23T01:59:03.554Z"),
"maxWireVersion" : 4,
"minWireVersion" : 0,
"ok" : 1
}
rs0:PRIMARY> rs.status()
{
"set" : "rs0",
"date" : ISODate("2017-11-23T02:00:26.312Z"),
"myState" : 1,
"term" : NumberLong(3),
"heartbeatIntervalMillis" : NumberLong(2000),
"members" : [
{
"_id" : 0,
"name" : "sign-mongo01.wangshibo.cn:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 368,
"optime" : {
"ts" : Timestamp(1511402420, 1),
"t" : NumberLong(3)
},
"optimeDate" : ISODate("2017-11-23T02:00:20Z"),
"electionTime" : Timestamp(1511402069, 1),
"electionDate" : ISODate("2017-11-23T01:54:29Z"),
"configVersion" : 5,
"self" : true
},
{
"_id" : 1,
"name" : "sign-mongo02.wangshibo.cn:27018",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 367,
"optime" : {
"ts" : Timestamp(1511402420, 1),
"t" : NumberLong(3)
},
"optimeDate" : ISODate("2017-11-23T02:00:20Z"),
"lastHeartbeat" : ISODate("2017-11-23T02:00:26.306Z"),
"lastHeartbeatRecv" : ISODate("2017-11-23T02:00:26.309Z"),
"pingMs" : NumberLong(0),
"syncingTo" : "sign-mongo01.wangshibo.cn:27017",
"configVersion" : 5
},
{
"_id" : 3,
"name" : "sign-mongo03.wangshibo.cn:27019",
"health" : 1,
"state" : 7,
"stateStr" : "ARBITER",
"uptime" : 93,
"lastHeartbeat" : ISODate("2017-11-23T02:00:26.306Z"),
"lastHeartbeatRecv" : ISODate("2017-11-23T02:00:25.306Z"),
"pingMs" : NumberLong(0),
"configVersion" : 5
}
],
"ok" : 1
}
至此,添加完成!!
再次测试主备切换。关闭172.16.51.216(primary)中删除服务进程:
[app@sign-mongo01 mongodb]$ pkill -9 mongod
[app@sign-mongo01 mongodb]$ ps -ef|grep mongod
app 9664 9398 0 09:50 pts/0 00:00:00 grep mongod
[app@sign-mongo01 mongodb]$ lsof -i:27017
[app@sign-mongo01 mongodb]$
然后到172.16.51.217:27018(secondary)查看,发现primary已经切换为172.16.51.217
[app@sign-mongo02 ~]$ mongo 172.16.51.217:27018
MongoDB shell version: 3.2.17-34-g4c1bae566c
connecting to: 172.16.51.217:27018/test
Server has startup warnings:
2017-11-22T21:46:38.417+0800 I CONTROL [initandlisten]
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten]
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-22T21:46:38.418+0800 I CONTROL [initandlisten]
rs0:PRIMARY> rs.status()
{
"set" : "rs0",
"date" : ISODate("2017-11-23T02:01:17.762Z"),
"myState" : 1,
"term" : NumberLong(4),
"heartbeatIntervalMillis" : NumberLong(2000),
"members" : [
{
"_id" : 0,
"name" : "sign-mongo01.wangshibo.cn:27017",
"health" : 0,
"state" : 8,
"stateStr" : "(not reachable/healthy)",
"uptime" : 0,
"optime" : {
"ts" : Timestamp(0, 0),
"t" : NumberLong(-1)
},
"optimeDate" : ISODate("1970-01-01T00:00:00Z"),
"lastHeartbeat" : ISODate("2017-11-23T02:01:17.316Z"),
"lastHeartbeatRecv" : ISODate("2017-11-23T02:01:04.327Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "Connection refused",
"configVersion" : -1
},
{
"_id" : 1,
"name" : "sign-mongo02.wangshibo.cn:27018",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 44080,
"optime" : {
"ts" : Timestamp(1511402475, 2),
"t" : NumberLong(4)
},
"optimeDate" : ISODate("2017-11-23T02:01:15Z"),
"infoMessage" : "could not find member to sync from",
"electionTime" : Timestamp(1511402475, 1),
"electionDate" : ISODate("2017-11-23T02:01:15Z"),
"configVersion" : 5,
"self" : true
},
{
"_id" : 3,
"name" : "sign-mongo03.wangshibo.cn:27019",
"health" : 1,
"state" : 7,
"stateStr" : "ARBITER",
"uptime" : 145,
"lastHeartbeat" : ISODate("2017-11-23T02:01:17.315Z"),
"lastHeartbeatRecv" : ISODate("2017-11-23T02:01:15.316Z"),
"pingMs" : NumberLong(0),
"configVersion" : 5
}
],
"ok" : 1
}
rs0:PRIMARY> show dbs
local 0.000GB
mydb 0.000GB
有上面信息可知,添加仲裁节点后,primary能正常启动切换了!~
现在看看arbiter,连接到172.16.51.218:27019
[app@sign-mongo03 ~]$ mongo 172.16.51.218:27019
MongoDB shell version: 3.2.17-34-g4c1bae566c
connecting to: 172.16.51.218:27019/test
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
http://docs.mongodb.org/
Questions? Try the support group
http://groups.google.com/group/mongodb-user
Server has startup warnings:
2017-11-23T09:58:34.978+0800 I CONTROL [initandlisten]
2017-11-23T09:58:34.978+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-11-23T09:58:34.978+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-23T09:58:34.978+0800 I CONTROL [initandlisten]
2017-11-23T09:58:34.978+0800 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2017-11-23T09:58:34.978+0800 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2017-11-23T09:58:34.978+0800 I CONTROL [initandlisten]
rs0:ARBITER> rs.slaveOk();
rs0:ARBITER> db.isMaster()
{
"hosts" : [
"sign-mongo01.wangshibo.cn:27017",
"sign-mongo02.wangshibo.cn:27018"
],
"arbiters" : [
"sign-mongo03.wangshibo.cn:27019"
],
"setName" : "rs0",
"setVersion" : 5,
"ismaster" : false,
"secondary" : false,
"primary" : "sign-mongo02.wangshibo.cn:27018",
"arbiterOnly" : true,
"me" : "sign-mongo03.wangshibo.cn:27019",
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 1000,
"localTime" : ISODate("2017-11-23T02:03:33.874Z"),
"maxWireVersion" : 4,
"minWireVersion" : 0,
"ok" : 1
}
rs0:ARBITER> show dbs
local 0.000GB
arbiter 最为仲裁者,没有数据副本存储在本地,能读取复制集的信息。
-------------------------------------------------------------------------------------------------
在primary主库上,创建locs数据库,该库的用户名为locsopr,密码为locsopr@123
[app@sign-mongo02 ~]$ mongo 172.16.51.217:27018
......
rs0:PRIMARY> use locs
switched to db locs
rs0:PRIMARY> db.createUser({user:"locsopr",pwd :"locsopr@123",roles:["readWrite"]})
Successfully added user: { "user" : "locsopr", "roles" : [ "readWrite" ] }
rs0:PRIMARY> show users; //查看当前库下的用户名
{
"_id" : "locs.locsopr",
"user" : "locsopr",
"db" : "locs",
"roles" : [
{
"role" : "readWrite",
"db" : "locs"
}
]
}
使用上面的用户登录primary主库
[app@sign-mongo02 ~]$ mongo 172.16.51.217:27018/locs -ulocsopr -plocsopr@123
.........
rs0:PRIMARY> show users
{
"_id" : "locs.locsopr",
"user" : "locsopr",
"db" : "locs",
"roles" : [
{
"role" : "readWrite",
"db" : "locs"
}
]
}
rs0:PRIMARY> show dbs
admin 0.000GB
local 0.000GB
rs0:PRIMARY>
再登录从库看下:
[app@sign-mongo01 ~]$ mongo 172.16.51.216:27017/locs -ulocsopr -plocsopr@123
.......
rs0:SECONDARY> rs.slaveOk();
rs0:SECONDARY> show users
{
"_id" : "locs.locsopr",
"user" : "locsopr",
"db" : "locs",
"roles" : [
{
"role" : "readWrite",
"db" : "locs"
}
]
}
rs0:SECONDARY> show dbs
admin 0.000GB
local 0.000GB
------------------------------------------------------------------------------------------------------------------------------------------------------- 上面介绍的是三台mongodb节点:一主一备一仲裁,这样,主节点挂了后,通过仲裁机制将primary自动切换到备机上! 如果上面的三台mongodb节点:一主两备,没有仲裁节点,那么主节点挂了后,primary会自动切换到其余两台备节点中的一台上!
一主两从(端口分别为27017、27018、27019)的mongodb配置和上面一主一从(端口分别为27017、27018)的配置一样。
多加的一个从节点,在主节点登陆mongodb,使用rs.add命令将这个成员加到集群中即可!
一主两从的模式,比如:
主节点sign-mongo01.wangshibo.cn的mongodb服务程序挂了后,另外两个从节点中的一个(比如sign-mongo02.wangshibo.cn)会自动变成primary主节点,
另一个节点sign-mongo03.wangshibo.cn则是新的主节点(sign-mongo02.wangshibo.cn)的从节点。
++++++++++++++++++++++++++++++如果想让切换回原来的主节点,做法如下+++++++++++++++++++++++++++++++
1)恢复原来的主节点sign-mongo01.wangshibo.cn的mongodb服务,使用命令rs.status() 确认数据集成员运行正常。
2)到次节点sign-mongo03.wangshibo.cn中登录mongodb,运行freeze使其120内不会变为主节点。
> rs.freeze(120)
3) 到新的主节点sign-mongo02.wangshibo.cn中强制切换主节点,stepDown将阻止长事务和写入操作
> rs.stepDown(120)
4)此时sign-mongo01.wangshibo.cn节点变成primary主节点。使用rs.status()命令可以查看到集群状态。
+++++++++++++++++++++++若要使某个节点永远不会变为主节点,设置优先级为0即可+++++++++++++++++++++++
登陆当前主节点的mongodb,执行下面操作:
rs0:PRIMARY> cfg = rs.conf()
rs0:PRIMARY> cfg.members[0].priority = 0.5
rs0:PRIMARY> cfg.members[1].priority = 0.5
rs0:PRIMARY> cfg.members[2].priority = 0
rs0:PRIMARY> rs.reconfig(cfg)
说明:
其中成员编号0/1/2为 rs.status()中的 "_id"值
members[2]表示sign-mongo03.wangshibo.cn,则它将永远不会变成主节点!因为优先级设置为0了!
++++++++++++++++++++++++++++++++移除一个复制成员(两种方法)++++++++++++++++++++++++++++++++++++
登陆当前主节点的mongodb,执行下面操作:
rs0:PRIMARY> rs.remove("sign-mongo03.wangshibo.cn:27019")
rs0:PRIMARY> rs.conf()
或者:
rs0:PRIMARY> cfg = rs.conf()
rs0:PRIMARY> cfg.members.splice(2,1)
rs0:PRIMARY> rs.reconfig(cfg)
移除后到移除的节点服务器(即sign-mongo03.wangshibo.cn),更改配置文件mongod.conf
#replSet=rs0 //将这一行注释
然后再重启mongodb服务,这就完成了移除(数据库文件仍保留在当前服务器)。