MongoDB之Replica Set(复制集复制)

MongoDB支持两种复制模式：

• 主从复制(Master/Slave)
• 复制集复制(Replica Set)

下面主要记录我在centos虚拟机上安装replica set，主要参考：http://docs.mongodb.org/manual/tutorial/deploy-replica-set/

 

首先准备好3份配置文件：

1 port = 27017

2 

3 dbpath = /home/bells/install/data1

4 logpath = /home/bells/install/log1/1.log

5 

6 fork = true

7 replSet = rs0

1 port = 27016

2 

3 dbpath = /home/bells/install/data2

4 logpath = /home/bells/install/log2/2.log

5 

6 fork = true

7 replSet = rs0

1 port = 27015

2 

3 dbpath = /home/bells/install/data3

4 logpath = /home/bells/install/log3/3.log

5 

6 fork = true

7 replSet = rs0

然后再启动这3个mongodb服务

sudo ./mongodb1/bin/mongod --smallfiles --config 1.conf

sudo ./mongodb2/bin/mongod --smallfiles --config 2.conf

sudo ./mongodb3/bin/mongod --smallfiles --config 3.conf

     其实smallfiles也应该写进*.conf文件中的。

最后配置：

   主要是通过下面的命令

     rs.initiate()   使用默认的配置初始化replica set在当前的服务器

     rs.status()    显示当前replica set的状态

     rs.add(serverInfo)   增加新的成员到replica set 中

     rs.addArb(serverInfo)    增加一个arbiter到replica set中

 1 rs.initiate()

 2 {

 3     "info2" : "no configuration explicitly specified -- making one",

 4     "me" : "localhost.localdomain:27017",

 5     "info" : "Config now saved locally.  Should come online in about a minute.",

 6     "ok" : 1

 7 }

 8 > rs.conf()

 9 {

10     "_id" : "rs0",

11     "version" : 1,

12     "members" : [

13         {

14             "_id" : 0,

15             "host" : "localhost.localdomain:27017"

16         }

17     ]

18 }

19 rs0:PRIMARY> rs.add("localhost.localdomain:27016")

20 { "ok" : 1 }

21 rs0:PRIMARY> rs.add("localhost.localdomain:27015")

22 { "ok" : 1 }

23 rs0:PRIMARY> rs.status()

24 {

25     "set" : "rs0",

26     "date" : ISODate("2014-02-23T01:43:16Z"),

27     "myState" : 1,

28     "members" : [

29         {

30             "_id" : 0,

31             "name" : "localhost.localdomain:27017",

32             "health" : 1,

33             "state" : 1,

34             "stateStr" : "PRIMARY",

35             "uptime" : 602,

36             "optime" : Timestamp(1393119782, 1),

37             "optimeDate" : ISODate("2014-02-23T01:43:02Z"),

38             "self" : true

39         },

40         {

41             "_id" : 1,

42             "name" : "localhost.localdomain:27016",

43             "health" : 1,

44             "state" : 5,

45             "stateStr" : "STARTUP2",

46             "uptime" : 17,

47             "optime" : Timestamp(0, 0),

48             "optimeDate" : ISODate("1970-01-01T00:00:00Z"),

49             "lastHeartbeat" : ISODate("2014-02-23T01:43:15Z"),

50             "lastHeartbeatRecv" : ISODate("2014-02-23T01:43:15Z"),

51             "pingMs" : 0,

52             "lastHeartbeatMessage" : "initial sync need a member to be primary or secondary to do our initial sync"

53         },

54         {

55             "_id" : 2,

56             "name" : "localhost.localdomain:27015",

57             "health" : 1,

58             "state" : 5,

59             "stateStr" : "STARTUP2",

60             "uptime" : 14,

61             "optime" : Timestamp(0, 0),

62             "optimeDate" : ISODate("1970-01-01T00:00:00Z"),

63             "lastHeartbeat" : ISODate("2014-02-23T01:43:16Z"),

64             "lastHeartbeatRecv" : ISODate("2014-02-23T01:43:16Z"),

65             "pingMs" : 1,

66             "lastHeartbeatMessage" : "syncThread: 12520 new file allocation failure"

67         }

68     ],

69     "ok" : 1

70 }

71 rs0:PRIMARY> db.person.insert({"name":"jack", "age":20})

72 rs0:PRIMARY> db.person.find()

73 { "_id" : ObjectId("5309529869d3a7216c59ef2a"), "name" : "jack", "age" : 20 }

1 [bells@localhost install]$ ./mongodb2/bin/mongo --port 27016

2 MongoDB shell version: 2.4.5

3 connecting to: 127.0.0.1:27016/test

4 rs0:SECONDARY> db.person.find()

5 error: { "$err" : "not master and slaveOk=false", "code" : 13435 }

6 rs0:SECONDARY> rs.slaveOk();

7 rs0:SECONDARY> db.person.find()

8 { "_id" : ObjectId("5309529869d3a7216c59ef2a"), "name" : "jack", "age" : 20 }

安装部署过程中，遇到两个问题：

1. 启动mongodb时，错误日志：

     

1 Sun Feb 23 09:47:57.930 [initandlisten] ERROR: Insufficient free space for journal files

2 Sun Feb 23 09:47:57.930 [initandlisten] Please make at least 3379MB available in /home/bells/install/data1/journal or use --smallfiles

3 Sun Feb 23 09:47:57.930 [initandlisten] 

4 Sun Feb 23 09:47:57.953 [initandlisten] exception in initAndListen: 15926 Insufficient free space for journals, terminating

      解决办法就是，启动的时候，加个   --smallfiles ： 这个参数默认值是false，如果设为true，则会是每个文件最大的大小限定为512M而不是默认的2G

2. 在secondary中，查询时：

1 rs0:SECONDARY> db.person.find()

2 error: { "$err" : "not master and slaveOk=false", "code" : 13435 }

这个是正常的，因为SECONDARY默认是不允许读写操作的，可以：

rs0:SECONDARY> db.slaveOk();

来解决！