SRE文档

深浅模式

官方在4.0版本后不建议再使用主从架构，mongodb4.0后废弃主从复制

wget https://fastdl.mongodb.org/linux/mongodb-linux-x86_64-3.6.23.tgz

ip地址说明
192.168.122.246master
192.168.122.245slave

master和副本集不能同时存在

1.master ​

[root@master 27017]# cat mongod.conf 
port=28017
dbpath=/data/mongodb_data/27017/data
logpath=/data/mongodb_data/27017/logs/mongod.log
pidfilepath=/data/mongodb_data/27017/mongod.pid
fork=true
logappend=true
logRotate=reopen
journal=true
storageEngine=wiredTiger
bind_ip = 0.0.0.0
master = true
source = 192.168.122.245:28017
#auth = true
[root@master 27017]# cat mongod.conf 
port=28017
dbpath=/data/mongodb_data/27017/data
logpath=/data/mongodb_data/27017/logs/mongod.log
pidfilepath=/data/mongodb_data/27017/mongod.pid
fork=true
logappend=true
logRotate=reopen
journal=true
storageEngine=wiredTiger
bind_ip = 0.0.0.0
master = true
source = 192.168.122.245:28017
#auth = true
  • 启动
/usr/local/mongo/bin/mongod --config /data/mongodb_data/27017/mongod.conf
/usr/local/mongo/bin/mongod --config /data/mongodb_data/27017/mongod.conf

2.slave ​

  • 配置
[root@slave 27017]# cat mongod.conf 
port=28017
dbpath=/data/mongodb_data/27017/data
logpath=/data/mongodb_data/27017/logs/mongod.log
pidfilepath=/data/mongodb_data/27017/mongod.pid
fork=true
logappend=true
logRotate=reopen
journal=true
storageEngine=wiredTiger
bind_ip = 0.0.0.0
slave = true 
source = 192.168.122.246:28017
#auth = true
[root@slave 27017]# cat mongod.conf 
port=28017
dbpath=/data/mongodb_data/27017/data
logpath=/data/mongodb_data/27017/logs/mongod.log
pidfilepath=/data/mongodb_data/27017/mongod.pid
fork=true
logappend=true
logRotate=reopen
journal=true
storageEngine=wiredTiger
bind_ip = 0.0.0.0
slave = true 
source = 192.168.122.246:28017
#auth = true
  • 启动
/usr/local/mongo/bin/mongod --config /data/mongodb_data/27017/mongod.conf
/usr/local/mongo/bin/mongod --config /data/mongodb_data/27017/mongod.conf

测试 ​

在master上面执行

/usr/local/mongo/bin/mongo 127.0.0.1:28017

创建新库 插入数据
> use new10         
switched to db new10
> db.new10.save({"name":22200})
WriteResult({ "nInserted" : 1 })
> db.new10.find()
/usr/local/mongo/bin/mongo 127.0.0.1:28017

创建新库 插入数据
> use new10         
switched to db new10
> db.new10.save({"name":22200})
WriteResult({ "nInserted" : 1 })
> db.new10.find()

在slave上查看

/usr/local/mongo/bin/mongo 127.0.0.1:28017

>rs.slaveOk()

> show dbs;
admin   0.000GB
config  0.000GB
local   0.000GB
test    0.000GB

> use test;
switched to db test

> show tables;
new10

> db.new10.find()
{ "_id" : ObjectId("61c9275b5745d52b72d861c5"), "name" : 22200 }
/usr/local/mongo/bin/mongo 127.0.0.1:28017

>rs.slaveOk()

> show dbs;
admin   0.000GB
config  0.000GB
local   0.000GB
test    0.000GB

> use test;
switched to db test

> show tables;
new10

> db.new10.find()
{ "_id" : ObjectId("61c9275b5745d52b72d861c5"), "name" : 22200 }

3.cmd ​

主从相关命令：

判断master ​

db.isMaster()：主从都可执行，用这个命令判断是不是master

> db.isMaster()
{
	"ismaster" : true,
	"maxBsonObjectSize" : 16777216,
	"maxMessageSizeBytes" : 48000000,
	"maxWriteBatchSize" : 100000,
	"localTime" : ISODate("2021-12-27T03:03:09.118Z"),
	"logicalSessionTimeoutMinutes" : 30,
	"minWireVersion" : 0,
	"maxWireVersion" : 6,
	"readOnly" : false,
	"ok" : 1
}
> db.isMaster()
{
	"ismaster" : true,
	"maxBsonObjectSize" : 16777216,
	"maxMessageSizeBytes" : 48000000,
	"maxWriteBatchSize" : 100000,
	"localTime" : ISODate("2021-12-27T03:03:09.118Z"),
	"logicalSessionTimeoutMinutes" : 30,
	"minWireVersion" : 0,
	"maxWireVersion" : 6,
	"readOnly" : false,
	"ok" : 1
}

获取主从信息master ​

db.getReplicationInfo()：主上执行，获取主从信息

#master
> db.getReplicationInfo()
{
	"logSizeMB" : 1292.5505857467651,
	"usedMB" : 0.02,
	"timeDiff" : 1634,
	"timeDiffHours" : 0.45,
	"tFirst" : "Sun Dec 26 2021 21:35:17 GMT-0500 (EST)",
	"tLast" : "Sun Dec 26 2021 22:02:31 GMT-0500 (EST)",
	"now" : "Sun Dec 26 2021 22:02:36 GMT-0500 (EST)"
}
#master
> db.getReplicationInfo()
{
	"logSizeMB" : 1292.5505857467651,
	"usedMB" : 0.02,
	"timeDiff" : 1634,
	"timeDiffHours" : 0.45,
	"tFirst" : "Sun Dec 26 2021 21:35:17 GMT-0500 (EST)",
	"tLast" : "Sun Dec 26 2021 22:02:31 GMT-0500 (EST)",
	"now" : "Sun Dec 26 2021 22:02:36 GMT-0500 (EST)"
}

获取主从信息master/slave ​

db.printReplicationInfo()：主从都可执行，获取主从信息

查看主从延时 ​

db.printSlaveReplicationInfo();：从库执行，查看主从延时

> db.printSlaveReplicationInfo();
WARNING: printSlaveReplicationInfo is deprecated and may be removed in the next major release. Please use printSecondaryReplicationInfo instead.
source: 192.168.122.246:28017
	syncedTo: Sun Dec 26 2021 22:04:01 GMT-0500 (EST)
	2 secs (0 hrs) behind the freshest member (no primary available at the moment)
> db.printSlaveReplicationInfo();
WARNING: printSlaveReplicationInfo is deprecated and may be removed in the next major release. Please use printSecondaryReplicationInfo instead.
source: 192.168.122.246:28017
	syncedTo: Sun Dec 26 2021 22:04:01 GMT-0500 (EST)
	2 secs (0 hrs) behind the freshest member (no primary available at the moment)

同步原理：

同步就是master上把对数据的更改操作记录到oplog中，然后slave抓取master的oplog执行。从这点看Oplog的功能和mysql的mysql-bin.的功能类似。Mysql-bin以二进制日志的形式存在，但是oplog是以一个mongodb的表的形式存在，该表在local库表名为oplog.$main，该表为循环写入形，所以不用定时清理