MongoDB Master-Slave switching (excellent)

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Master-Slave synchronization:

MD01 10.0.0.11 Master
MD02 10.0.0.12 Slave
MD03 10.0.0.14 Slave

#建立数据库目录

Mkdir-p/elain/apps/mongodb/mkdir-p/elain/data/mongodb/db/mkdir-p/elain/logs/mongodb/

Note:
1, do not need to copy the complete data like MySQL in the past, Concou boot will be brake copy master library full data.
2, Concou automatically configured as read-only.
3, MongoDB first boot time is longer, need to pay attention to wait.
4, most of the management command in the Admin library to execute the use admin

Related parameters:./mongod--help
--autoresync when the data from the server is found to be not up to date, the request to synchronize data from the master server begins
--slavedelay synchronization delay, Unit: SEC

Master-From
Start as master server

/elain/apps/mongodb/bin/mongod--fork--master--oplogsize=4096--port 27001--dbpath/elain/data/mongodb/db--logpath /elain/logs/mongodb/mongodb.log

As starting from the server and indicating the primary server address. --autoresync to force all data to be synchronized from the primary server

/elain/apps/mongodb/bin/mongod--fork--slave--source 10.0.0.11:27001--port 27001--dbpath/elain/data/mongodb/db-- Logpath/elain/logs/mongodb/mongodb.log

Note: You can add the following common parameters when starting from
--slavedelay #延时复制 units of seconds
--autoresync #自动重新同步
--only #复制指定的数据库, all libraries are copied by default
--oplogsize #主节点的oplog日志大小, the unit is m, it is recommended to set a large point (change oplog size, just stop the main library, delete local.*, and then add--oplogsize=* reboot, * represents the size)

If you find that the master never synchronizes, manually sync from the

Db.runcommand ({"Resync": 1})

Status Query

Db.runcommand ({"IsMaster": 1})

#主还是从

Querying the main library address on the Plex library

> Use local;  Switched to DB local > Db.sources.find (); {"_id": ObjectId ("4e9105515d704346c8796407"), "host": "10.0.0.11:27001", "source": "Main", "Syncedto": {"T": 131815 5992000, "I": 1}}

#查看各Collection状态

Db.printcollectionstats ();

#查看主从复制状态

Db.printreplicationinfo ();

Test Master
Create a new database on the primary server

MONGO--port 27001 >show dbs >use elaindb >db.blog.save ({title: "new Article"})

Viewing synchronized data from a server

MONGO--port 27001

#在从库插入数据的操作 will prompt not master

> Use elaindb;  Switched to DB elaindb > Db.blog.find (); {"_id": ObjectId ("4e9174b48443c8ef12b30c56"), "title": "New Article"}

#查看主从同步信息:

> Db.printreplicationinfo ();  This is a slave, printing slave replication info. source:10.0.0.11:27001 Syncedto:sun Oct 18:37:12 gmt+0800 (CST) = secs ago (0.0 1hrs)

>db.printslavereplicationinfo ();

#此为同步过来的数据, Test success

Additional:

Add and remove Sources:
You can specify the master node with--source when you start the slave node, or you can configure the source in the shell.

Start a slave with a port of 27002

/elain/apps/mongodb/bin/mongod--fork--slave--port 27002--dbpath/elain/data/mongodb/testdb--logpath/elain/logs/ Mongodb/mongodb.log

Login:

MONGO--port 27002 [root@md03 ~]# MONGO--port 27002 MongoDB Shell version:2.0.0 connecting To:127.0.0.1:27002/test > Show dbs local (empty)

Add to slave node

>use Local >db.sources.insert ({"Host": "10.0.0.11:27001"});

#查看显示正在同步

> Db.sources.find (); {"_id": ObjectId ("4e9111e1c29bbd9b9cd31d4e"), "host": "10.0.0.11:27001", "source": "Main", "Syncedto": {"T": 131815 6782000, "I": 246}, "Dbsnextpass": {"TestDB": True, "TESTDB1": True}}

#同步完成后

> Db.sources.find (); {"_id": ObjectId ("4e9111e1c29bbd9b9cd31d4e"), "host": "10.0.0.11:27001", "source": "Main", "Syncedto": {"T": 131815 6782000, "I": 256}}

Change Source: (assuming 10.0.0.12 is also the master library)

Db.sources.insert ({"Host": "10.0.0.12:27001"}); Db.sources.remove ({"Host": "10.0.0.11:27001"});

If authentication is used in replication, you need to add the REPL user to the local library to copy

>user Local; > Db.adduser ("Repl", "elain123");

Appendix I, Slave replacement Master
If the primary server 10.0.0.11 down,
You need to replace the master service with a 10.0.0.12 machine.

The steps are as follows:
#停止 10.0.0.12 Process (Mongod)

Kill-2 ' Ps-ef|grep mongod|grep-v Grep|awk ' {print $} '

#删除 local.* in the 10.0.0.12 data Catalog

Rm-rf/elain/data/mongodb/db/local.*

#以--master mode start 10.0.0.12

/elain/apps/mongodb/bin/mongod--fork--master--oplogsize=4096--port 27001--dbpath/elain/data/mongodb/db--logpath /elain/logs/mongodb/mongodb.log

Appendix II, Switching Master/slave roles
Switch between the main library 10.0.0.11 and the role from the library 10.0.0.12

The steps are as follows: (Command slightly)

Pauses the write operation on the main library with the Fsync command.
To close a service from the library
Emptying the local.* file from the library
Restart from library service with-MASTER option
Performs a write operation from the library, initializes the Oplog, and obtains a synchronous start point
Close from the library service, at which point the new local.* file is already available from the library
Close the main library service and replace the local.* file on the main library with a new local.* file from the library (it is recommended to compress and copy first)
Restart from library service with-MASTER option
Restart the main library service by adding a-fastsync option on the option to start slave

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This article link address: MongoDB Combat Series III: MongoDB's master-slave deployment

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