mongo 三种集群

网上关于三种集群方式的搭建方式很多,都是分开来介绍的。Replica Set (复制集成)主要是做主从库的,但是没法实现负载均衡的效果,真正实现这个的,是Sharding(分片集群),通过数据分布在每个分片上而实现。所以,如果只用分片,如果一个只有一个主库,那么挂了就真的挂了。所以在我尝试的集群部署采用的Replica Set+Sharding的方式。OS是Redhat_x64系统,客户端用的是Java客户端。Mongodb版本是mongodb-linux-x86_64-2.4.9.tgz。

要构建一个 MongoDB Sharding Cluster,需要三种角色:

l Shard Server: mongod 实例,用于存储实际的数据块,实际生产环境中一个shard server角色可由几台机器组个一个relica set承担,防止主机单点故障

l Config Server: mongod 实例,存储了整个 Cluster Metadata,其中包括 chunk 信息。

l Route Server: mongos 实例,前端路由,客户端由此接入,且让整个集群看上去像单一数据库,前端应用可以透明使用。

1. 分别在3台机器运行一个mongod实例(称为mongod shard11,mongod shard12,mongod shard13)组织replica set1,作为cluster的shard1

2. 1台机器运行一个mongod实例(称为mongod shard22,单机作为cluster的shard2

3. 每台机器运行一个mongod实例,作为3个config server

4. 每台机器运行一个mongs进程,用于客户端连接

主机

IP

端口信息

Server1

172.17.253.216

mongod shard11:27017
mongod config1:20000
mongs1:30000

Server2

172.17.253.217

mongod shard12:27017
mongod shard22:27018
mongod config2:20000
mongs2:30000

Server3

172.17.253.67

mongod shard13:27017
mongod config3:20000
mongs3:30000

2.1软件准备

1. 安装monodb软件

su – mongodb
tar zxvf mongodb-linux-x86_64-2.4.9.tgz

创建数据目录
根据本例sharding架构图所示,在各台sever上创建shard数据文件目录
Server1:

cd /opt/mongodb
mkdir -p data/shard11 

Server2:

cd /opt/mongodb
mkdir -p data/shard12
mkdir -p data/shard22 

Server3:
cd /opt/mongodb
mkdir -p data/shard13

2.2配置relica sets(复制集)

1. 配置shard1所用到的replica sets:

方式一:

Server1:
cd /opt/mongodb/bin
./mongod –shardsvr –replSet shard1 –port 27017 –dbpath /mongodb/data/shard11 –oplogSize 100 –logpath /mongodb/data/shard11.log –logappend –fork

Server2:
cd /opt/mongodb/bin
./mongod –shardsvr –replSet shard1 –port 27017 –dbpath /mongodb/data/shard12 –oplogSize 100 –logpath /mongodb/data/shard12.log –logappend –fork

Server3:
cd /opt/mongodb/bin

./mongod –shardsvr –replSet shard1 –port 27017 –dbpath /mongodb/data/shard13 –oplogSize 100 –logpath /mongodb/data/shard13.log –logappend –fork

方式二:

由于配置文件比较多,建议写在文件中

Server1:

vim /opt/mongodb/bin/shard11.conf

#shard11.conf
dbpath=/opt/mongodb/data/shard11
logpath = /opt/mongodb/data/shard11.log
pidfilepath = /opt/mongdb/shard11.pid
directoryperdb = true
logappend = true
replSet = shard1
bind_ip=172.17.253.216
port = 27017
oplogSize = 100
fork = true
noprealloc=true  
cd /opt/mongodb/bin

./mongod -shardsvr -f shard11.conf
当看到下面的内容表示启动成功:

about to fork child process, waiting until server is ready for connections.
all output going to: /opt/mongodb/data/shard11.log
forked process: 14867
child process started successfully, parent exiting
Server2:同理

vim /opt/mongodb/bin/shard12.conf

#shard12.conf
dbpath=/opt/mongodb/data/shard12
logpath = /opt/mongodb/data/shard12.log
pidfilepath = /opt/mongdb/shard12.pid
directoryperdb = true
logappend = true
replSet = shard1
bind_ip=172.17.253.217
port = 27017
oplogSize = 100
fork = true
noprealloc=true  
 
cd /opt/mongodb/bin
./mongod -shardsvr -f shard12.conf

Server3:同理

vim /opt/mongodb/bin/shard12.conf

#shard13.conf
dbpath=/opt/mongodb/data/shard13
logpath = /opt/mongodb/data/shard13.log
pidfilepath = /opt/mongdb/shard13.pid
directoryperdb = true
logappend = true
replSet = shard1
bind_ip=172.17.253.67
port = 27017
oplogSize = 100
fork = true
noprealloc=true  
cd /opt/mongodb/bin
./mongod -shardsvr -f shard12.conf

参数解释:

dbpath:数据存放目录

logpath:日志存放路径

pidfilepath:进程文件,方便停止mongodb

directoryperdb:为每一个数据库按照数据库名建立文件夹存放

logappend:以追加的方式记录日志

replSet:replica set的名字

bind_ip:mongodb所绑定的ip地址

port:mongodb进程所使用的端口号,默认为27017

oplogSize:mongodb操作日志文件的最大大小。单位为Mb,默认为硬盘剩余空间的5%

fork:以后台方式运行进程

noprealloc:不预先分配存储

初始化replica set

配置主,备,仲裁节点,可以通过客户端连接mongodb,也可以直接在三个节点中选择一个连接mongodb。
用mongo连接其中一个mongod,执行:

[root@localhost bin]# ./mongo 172.17.253.217:27017
MongoDB shell version: 2.4.9
connecting to: 172.17.253.217:27017/test
> use admin
switched to db admin
> config={_id:'shard1',members:[{_id:0,host:'172.17.253.216:27017',priority:2},{_id:1,host:'172.17.253.217:27017',priority:1},{_id:2,host:'172.17.253.67:27017',arbiterOnly:true}]}
{
	"_id" : "shard1",
	"members" : [
		{
			"_id" : 0,
			"host" : "172.17.253.216:27017",
			"priority" : 2
		},
		{
			"_id" : 1,
			"host" : "172.17.253.217:27017",
			"priority" : 1
		},
		{
			"_id" : 2,
			"host" : "172.17.253.67:27017",
			"arbiterOnly" : true
		}
	]
}
> rs.initiate(config)#使配置生效  

{
	"info" : "Config now saved locally.  Should come online in about a minute.",
	"ok" : 1
}

config是可以任意的名字,当然最好不要是mongodb的关键字,conf,config都可以。最外层的_id表示replica set的名字,members里包含的是所有节点的地址以及优先级。优先级最高的即成为主节点,即这里的172.17.253.216:27017。特别注意的是,对于仲裁节点,需要有个特别的配置——arbiterOnly:true。这个千万不能少了,不然主备模式就不能生效。 

配置的生效时间根据不同的机器配置会有长有短,配置不错的话基本上十几秒内就能生效,有的配置需要一两分钟。如果生效了,执行rs.status()命令会看到如下信息:

> rs.status()
{
    "set" : "shard1",
    "date" : ISODate("2014-02-13T17:39:46Z"),
    "myState" : 2,
    "members" : [
        {
            "_id" : 0,
            "name" : "172.17.253.216:27017",
            "health" : 1,
            "state" : 6,
            "stateStr" : "UNKNOWN",
            "uptime" : 42,
            "optime" : Timestamp(0, 0),
            "optimeDate" : ISODate("1970-01-01T00:00:00Z"),
            "lastHeartbeat" : ISODate("2014-02-13T17:39:44Z"),
            "lastHeartbeatRecv" : ISODate("1970-01-01T00:00:00Z"),
            "pingMs" : 1,
            "lastHeartbeatMessage" : "still initializing"
        },
        {
            "_id" : 1,
            "name" : "172.17.253.217:27017",
            "health" : 1,
            "state" : 2,
            "stateStr" : "SECONDARY",
            "uptime" : 3342,
            "optime" : Timestamp(1392313137, 1),
            "optimeDate" : ISODate("2014-02-13T17:38:57Z"),
            "self" : true
        },
        {
            "_id" : 2,
            "name" : "172.17.253.67:27017",
            "health" : 1,
            "state" : 5,
            "stateStr" : "STARTUP2",
            "uptime" : 40,
            "lastHeartbeat" : ISODate("2014-02-13T17:39:44Z"),
            "lastHeartbeatRecv" : ISODate("2014-02-13T17:39:44Z"),
            "pingMs" : 0
        }
    ],
    "ok" : 1
}
> rs.initiate()
{
	"errmsg" : "exception: Can't take a write lock while out of disk space",
	"code" : 14031,
	"ok" : 0
}

我们会发现,本来应该是主库的显示unkown,仲裁库显示STARTUP2。报错:
Can't take a write lock while out of disk space
这个如何解决呢,经过百度一番之后,

将lock文件删除
rm /var/lib/mongodb/mongod.lock

最好也把journal日志删除,那玩意也很占硬盘,重启mongodb服务

在次尝试:  
root@Labs06 bin]# ./mongo 172.17.253.216:27017
MongoDB shell version: 2.4.9
connecting to: 172.17.253.216:27017/test
shard1:PRIMARY> 
shard1:PRIMARY> rs.status()
{
	"set" : "shard1",
	"date" : ISODate("2014-02-13T10:53:12Z"),
	"myState" : 1,
	"members" : [
		{
			"_id" : 0,
			"name" : "172.17.253.216:27017",
			"health" : 1,
			"state" : 1,
			"stateStr" : "PRIMARY",
			"uptime" : 921,
			"optime" : Timestamp(1392313137, 1),
			"optimeDate" : ISODate("2014-02-13T17:38:57Z"),
			"self" : true
		},
		{
			"_id" : 1,
			"name" : "172.17.253.217:27017",
			"health" : 1,
			"state" : 2,
			"stateStr" : "SECONDARY",
			"uptime" : 815,
			"optime" : Timestamp(1392313137, 1),
			"optimeDate" : ISODate("2014-02-13T17:38:57Z"),
			"lastHeartbeat" : ISODate("2014-02-13T10:53:10Z"),
			"lastHeartbeatRecv" : ISODate("2014-02-13T10:53:11Z"),
			"pingMs" : 1,
			"syncingTo" : "172.17.253.216:27017"
		},
		{
			"_id" : 2,
			"name" : "172.17.253.67:27017",
			"health" : 1,
			"state" : 7,
			"stateStr" : "ARBITER",
			"uptime" : 776,
			"lastHeartbeat" : ISODate("2014-02-13T10:53:11Z"),
			"lastHeartbeatRecv" : ISODate("2014-02-13T10:53:10Z"),
			"pingMs" : 0
		}
	],
	"ok" : 1
} 

同样方法,配置shard2用到的replica sets:

这里我们之添加172.17.253.217:27018单机

2.3配置三台config server,启动配置节点

Server1:
mkdir -p /mongodb/data/config
./mongod –configsvr –dbpath /mongodb/data/config –port 20000 –logpath /mongodb/data/config.log –logappend –fork #config server也需要dbpath

Server2:
mkdir -p /mongodb/data/config
./mongod –configsvr –dbpath /mongodb/data/config –port 20000 –logpath /mongodb/data/config.log –logappend –fork

Server3:
mkdir -p /mongodb/data/config
./mongod –configsvr –dbpath /mongodb/data/config –port 20000 –logpath /mongodb/data/config.log –logappend –fork

方式二:

由于配置文件比较多,建议写在文件中

Server1:

#config.conf

dbpath=/opt/mongodb/data/config
logpath = /opt/mongodb/data/config.log
logappend = true
bind_ip=172.17.253.216
port = 20000
fork = true
[root@localhost bin]# ./mongod -configsvr -f config.conf 
about to fork child process, waiting until server is ready for connections.
forked process: 24132
all output going to: /opt/mongodb/data/config.log
child process started successfully, parent exiting
Server2:
dbpath=/opt/mongodb/data/config
logpath = /opt/mongodb/data/config.log
logappend = true
bind_ip=172.17.253.217
port = 20000
fork = true
Server3:
dbpath=/opt/mongodb/data/config
logpath = /opt/mongodb/data/config.log
logappend = true
bind_ip=172.17.253.67
port = 20000
fork = true
2.4启动路由节点

在每一台server上都执行

[root@localhost bin]# ./mongos --configdb 172.17.253.217:20000,172.17.253.67:20000,172.17.253.216:20000 -port 30000 -chunkSize 5 -logpath /opt/mongodb/data/mongos.log -logappend -fork
about to fork child process, waiting until server is ready for connections.
forked process: 26210
all output going to: /opt/mongodb/data/mongos.log
child process started successfully, parent exiting
2.5配置Sharding

连接到其中一个mongos进程,并切换到admin数据库做以下配置
1. 连接到mongs,并切换到admin
./mongo 172.17.253.217:30000/admin这里必须连接路由节点

>db
Admin
2. 加入shards
如里shard是单台服务器,用>db.runCommand( { addshard : “[:]” } )这样的命令加入,如果shard是replica sets,用replicaSetName/[:port][,serverhostname2[:port],…]这样的格式表示,例如本例执行:

mongos> db.runCommand( { addshard : "shard1/172.17.253.216:27017,172.17.253.67:27017,172.17.253.217:27017",name:"shard1",maxsize:20480});
{ "shardAdded" : "shard1", "ok" : 1 }

mongos> db.runCommand( { addshard : "shard2/172.17.253.217:27018",name:"shard2",maxsize:20480});
{ "shardAdded" : "shard2", "ok" : 1 }
mongos> db.runCommand({listshards:1})
{
	"shards" : [
		{
			"_id" : "shard1",
			"host" : "shard1/172.17.253.216:27017,172.17.253.217:27017"
		},
		{
			"_id" : "shard2",
			"host" : "shard2/172.17.253.217:27018"
		}
	],
	"ok" : 1
}
注意:在添加第二个shard时,出现error:test database 已经存在的错误,这里用mongo命令连接到第二个replica set,用db.dropDatabase()命令把test数据库给删除然后就可加入

3. 可选参数
Name:用于指定每个shard的名字,不指定的话系统将自动分配
maxSize:指定各个shard可使用的最大磁盘空间,单位megabytes

4. Listing shards
>db.runCommand( { listshards : 1 } )
如果列出了以上二个你加的shards,表示shards已经配置成功

2.6数据库分片以及Collecton分片

1、激活数据库分片

命令:
> db.runCommand( { enablesharding : “” } );
通过执行以上命令,可以让数据库跨shard,如果不执行这步,数据库只会存放在一个shard,一旦激活数据库分片,数据库中不同的collection将被存放在不同的shard上,但一个collection仍旧存放在同一个shard上,要使单个collection也分片,还需单独对collection作些操作

2、Collection分片

要使单个collection也分片存储,需要给collection指定一个分片key,通过以下命令操作:
> db.runCommand( { shardcollection : “”,key : });
注:
a. 分片的collection系统会自动创建一个索引(也可用户提前创建好)
b. 分片的collection只能有一个在分片key上的唯一索引,其它唯一索引不被允许
One note: a sharded collection can have only one unique index, which must exist on the shard key. No other unique indexes can exist on the collection.

2.7分片collection例子

>db.runCommand( { shardcollection : “test.c1″,key : {id: 1} } )
>for (var i = 1; i <= 200003; i++) db.c1.save({id:i,value1:”1234567890″,value2:”1234567890″,value3:”1234567890″,value4:”1234567890″});
> db.c1.stats()(该命令可以查看表的存储状态)

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