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分类: NOSQL

2013-03-07 14:03:43

mongodb  replica set config

 参考:

1.     rs.conf()  replica set 相关的配置类,具有的属性:

a)       _id, replica set 名称。

b)      members。各节点相关属性(id,host,priority,tag,slaveDelay…)。

c)       settings。配置信息。

2.     rs 操作类:


       rs.status()  返回当前replica set 的状态信息。每个memberhosthealthroleoptime等信息

       rs.initate()   初始化配置一个复制集,加入参数则按照参数设定配置。

       rs.conf()      返回当前复制集的配置信息。

       rs.reconfig()       在线更新复制集配置信息,如对member host等属性的更改。

       rs.add()              添加节点。参数可以是hostport,也可是完整的结构体。

       rs.stepDown()   primary 主动降级为slave

       rs.freeze()          设置节点一定时间内不能被选为primary,在切换的时候人工干预。

       rs.remove()        移除节点。

       db.isMaster()     返回整个复制集hosts,以及角色的分配情况。在rs.status()也能看到。

搭建步骤:

1.     启动实例

mongod --port 27018 --dbpath /data/mongodb/rs-1 --replSet rs0 &

mongod --port 27019 --dbpath /data/mongodb/rs-2 --replSet rs0 &

mongod --port 27020 --dbpath /data/mongodb/rs-3 --replSet rs0 &

2.     配置节点

ubuntu@os-cloud-12:~$ mongo localhost:27018

MongoDB shell version: 2.0.4

connecting to: localhost:27018/test

> rs.status()

{

       "startupStatus" : 3,

       "info" : "run rs.initiate(...) if not yet done for the set",

       "errmsg" : "can't get local.system.replset config from self or any seed (EMPTYCONFIG)",

       "ok" : 0

}

#使用默认配置初始化。

> rs.initiate()

{

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

       "me" : "os-cloud-12:27018",

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

       "ok" : 1

}

> rs.conf()

{

       "_id" : "rs0",

       "version" : 1,

       "members" : [

              {

                     "_id" : 0,

                     "host" : "os-cloud-12:27018"

              }

       ]

}

#初始化后,默认当前hostprimary,继续添加节点

PRIMARY> rs.add("os-cloud-12:27019")

{ "ok" : 1 }

PRIMARY> rs.add("os-cloud-12:27020")

{ "ok" : 1 }

#查看配置情况和当前状态

PRIMARY> rs.conf()

{

       "_id" : "rs0",

       "version" : 3,

       "members" : [

              {

                     "_id" : 0,

                     "host" : "os-cloud-12:27018"

              },

              {

                     "_id" : 1,

                     "host" : "os-cloud-12:27019"

              },

              {

                     "_id" : 2,

                     "host" : "os-cloud-12:27020"

              }

       ]

}

PRIMARY> rs.status()

{

       "set" : "rs0",

       "date" : ISODate("2012-11-24T03:01:54Z"),

       "myState" : 1,

       "syncingTo" : "os-cloud-12:27018",

       "members" : [

              {

                     "_id" : 0,

                     "name" : "os-cloud-12:27018",

                     "health" : 1,

                     "state" : 2,

                     "stateStr" : "SECONDARY",

                     "uptime" : 60854,

                     "optime" : {

                            "t" : 1353665255000,

                            "i" : 1

                     },

                     "optimeDate" : ISODate("2012-11-23T10:07:35Z"),

                     "lastHeartbeat" : ISODate("2012-11-24T03:01:53Z"),

                     "pingMs" : 0

              },

              {

                     "_id" : 1,

                     "name" : "os-cloud-12:27019",

                     "health" : 1,

                     "state" : 2,

                     "stateStr" : "SECONDARY",

                     "uptime" : 60854,

                     "optime" : {

                            "t" : 1353665255000,

                            "i" : 1

                     },

                     "optimeDate" : ISODate("2012-11-23T10:07:35Z"),

                     "lastHeartbeat" : ISODate("2012-11-24T03:01:53Z"),

                     "pingMs" : 0

              },

              {

                     "_id" : 2,

                     "name" : "os-cloud-12:27020",

                     "health" : 1,

                     "state" : 1,

                     "stateStr" : "PRIMARY",

                     "optime" : {

                            "t" : 1353665255000,

                            "i" : 1

                     },

                     "optimeDate" : ISODate("2012-11-23T10:07:35Z"),

                     "self" : true

              }

       ],

       "ok" : 1

}

3.     primary 切换。

PRIMARY> rs.stepDown()

Fri Nov 23 18:12:31 DBClientCursor::init call() failed

Fri Nov 23 18:12:31 query failed : admin.$cmd { replSetStepDown: 60.0 } to: localhost:27018

Fri Nov 23 18:12:31 Error: error doing query: failed shell/collection.js:151

Fri Nov 23 18:12:31 trying reconnect to localhost:27018

Fri Nov 23 18:12:31 reconnect localhost:27018 ok

SECONDARY> rs.status()

4.     member 属性的修改。

a)       重启需要修改的mongodb 节点,以新的配置加入复制集

b)      primary中修改其属性值(rs.reconfig()

 

选举策略:

1 get maxLocalOpOrdinal from each server.

2 if a majority of servers are not up (from this server's POV), remain in Secondary mode and stop.

3 if the last op time seems very old, stop and await human intervention.

4 else, using a consensus protocol, pick the server with the highest maxLocalOpOrdinal as the Primary.

 

http://blog.nosqlfan.com/html/2523.html 

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