MongoDB之分片

1、环境
操作系统信息：


服务器规划：


从上表可以看到有四个组件：mongos、config server、shard、replica set。
mongos：数据库集群请求的入口，所有的请求都通过mongos进行协调，不需要在应用程序添加一个路由选择器，mongos自己就是一个请求分发中心，它负责把对应的数据请求转发到对应的shard服务器上。在生产环境通常有多mongos作为请求的入口，防止其中一个挂掉所有的mongodb请求都没有办法操作。
config server：顾名思义为配置服务器，存储所有数据库元信息（路由、分片）的配置。mongos本身没有物理存储分片服务器和数据路由信息，只是缓存在内存里，配置服务器则实际存储这些数据。mongos第一次启动或者关掉重启就会从 config server 加载配置信息，以后如果配置服务器信息变化会通知到所有的 mongos 更新自己的状态，这样 mongos 就能继续准确路由。在生产环境通常有多个 config server 配置服务器（必须配置为１个或者３个），因为它存储了分片路由的元数据，防止数据丢失！
shard：分片（sharding）是指将数据库拆分，将其分散在不同的机器上的过程。将数据分散到不同的机器上，不需要功能强大的服务器就可以存储更多的数据和处理更大的负载。基本思想就是将集合切成小块，这些块分散到若干片里，每个片只负责总数据的一部分，最后通过一个均衡器来对各个分片进行均衡（数据迁移）。
replica set：中文翻译副本集，其实就是shard的备份，防止shard挂掉之后数据丢失。复制提供了数据的冗余备份，并在多个服务器上存储数据副本，提高了数据的可用性， 并可以保证数据的安全性。
仲裁者（Arbiter）：是复制集中的一个MongoDB实例，它并不保存数据。仲裁节点使用最小的资源，不能将Arbiter部署在同一个数据集节点中，可以部署在其他应用服务器或者监视服务器中，也可部署在单独的虚拟机中。为了确保复制集中有奇数的投票成员（包括primary），需要添加仲裁节点做为投票，否则primary不能运行时不会自动切换primary。
简单了解之后，可以这样总结一下，应用请求mongos来操作mongodb的增删改查，配置服务器存储数据库元信息，并且和mongos做同步，数据最终存入在shard（分片）上，为了防止数据丢失同步在副本集中存储了一份，仲裁在数据存储到分片的时候决定存储到哪个节点。
总共规划了mongos 3个， config server 3个，数据分3片 shard server 3个，每个shard 有一个副本一个仲裁也就是 3 * 2 = 6 个，总共需要部署15个实例。这些实例可以部署在独立机器也可以部署在一台机器，我们这里测试资源有限，只准备了 3台机器，在同一台机器只要端口不同就可以了。


2、安装mongodb
分别在3台机器上面安装mongodb
[root@D2-POMS15 ~]# tar -xvzf mongodb-linux-x86_64-rhel62-3.4.7.tgz -C /usr/local/
[root@D2-POMS15 ~]# mv /usr/local/mongodb-linux-x86_64-rhel62-3.4.7/ /usr/local/mongodb

配置环境变量
[root@D2-POMS15 ~]# vim .bash_profile
export PATH=$PATH:/usr/local/mongodb/bin/
[root@D2-POMS15 ~]# source .bash_profile


分别在每台机器建立conf、mongos、config、shard1、shard2、shard3六个目录，因为mongos不存储数据，只需要建立日志文件目录即可。
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/conf
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/mongos/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/config/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/config/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard1/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard1/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard2/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard2/log
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard3/data
[root@D2-POMS15 ~]# mkdir -p /usr/local/mongodb/shard3/log


3、config server配置服务器
mongodb3.4以后要求配置服务器也创建副本集，不然集群搭建不成功。
在三台服务器上面添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/config.conf
## 配置文件内容
pidfilepath = /usr/local/mongodb/config/log/configsrv.pid
dbpath = /usr/local/mongodb/config/data
logpath = /usr/local/mongodb/config/log/congigsrv.log
logappend = true

bind_ip = 0.0.0.0
port = 21000
fork = true

#declare this is a config db of a cluster;
configsvr = true

#副本集名称
replSet=configs

#设置最大连接数
maxConns=20000

分别启动三台服务器的config server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/config.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15368
child process started successfully, parent exiting

登录任意一台配置服务器，初始化配置副本集
[root@D2-POMS15 ~]# mongo --port 21000
> config = {
...    _id : "configs",
...     members : [
...         {_id : 0, host : "10.163.97.15:21000" },
...         {_id : 1, host : "10.163.97.16:21000" },
...         {_id : 2, host : "10.163.97.17:21000" }
...     ]
... }
{
        "_id" : "configs",
        "members" : [
                {
                        "_id" : 0,
                        "host" : "10.163.97.15:21000"
                },
                {
                        "_id" : 1,
                        "host" : "10.163.97.16:21000"
                },
                {
                        "_id" : 2,
                        "host" : "10.163.97.17:21000"
                }
        ]
}
> rs.initiate(config)
{ "ok" : 1 }

其中，"_id" : "configs"应与配置文件中配置的replSet一致，"members" 中的 "host" 为三个节点的 ip 和 port。

4、配置分片副本集(三台机器)
设置第一个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard1.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard1/log/shard1.pid
dbpath = /usr/local/mongodb/shard1/data
logpath = /usr/local/mongodb/shard1/log/shard1.log
logappend = true

bind_ip = 0.0.0.0
port = 27001
fork = true

#打开web监控
httpinterface=true
rest=true

#副本集名称
replSet=shard1

#declare this is a shard db of a cluster;
shardsvr = true

#设置最大连接数
maxConns=20000

启动三台服务器的shard1 server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard1.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15497
child process started successfully, parent exiting

登陆一台服务器（不要在仲裁节点），初始化副本集
[root@D2-POMS15 ~]# mongo --port 27001
#使用admin数据库
> use admin
switched to db admin
#定义副本集配置，第三个节点的 "arbiterOnly":true 代表其为仲裁节点。
> config = {
...    _id : "shard1",
...     members : [
...         {_id : 0, host : "10.163.97.15:27001" },
...         {_id : 1, host : "10.163.97.16:27001" },
...         {_id : 2, host : "10.163.97.17:27001" , arbiterOnly: true }
...     ]
... }
{
        "_id" : "shard1",
        "members" : [
                {
                        "_id" : 0,
                        "host" : "10.163.97.15:27001"
                },
                {
                        "_id" : 1,
                        "host" : "10.163.97.16:27001"
                },
                {
                        "_id" : 2,
                        "host" : "10.163.97.17:27001",
                        "arbiterOnly" : true
                }
        ]
}
#初始化副本集配置
> rs.initiate(config);
{ "ok" : 1 }


设置第二个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard2.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard2/log/shard2.pid
dbpath = /usr/local/mongodb/shard2/data
logpath = /usr/local/mongodb/shard2/log/shard2.log
logappend = true

bind_ip = 0.0.0.0
port = 27002
fork = true

#打开web监控
httpinterface=true
rest=true

#副本集名称
replSet=shard2

#declare this is a shard db of a cluster;
shardsvr = true

#设置最大连接数
maxConns=20000

启动三台服务器的shard2 server：
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard2.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15622
child process started successfully, parent exiting

登陆一台服务器（不要在仲裁节点），初始化副本集
[root@D2-POMS15 ~]# mongo --port 27002
> use admin
switched to db admin
> config = {
...    _id : "shard2",
...     members : [
...         {_id : 0, host : "10.163.97.15:27002"  , arbiterOnly: true },
...         {_id : 1, host : "10.163.97.16:27002" },
...         {_id : 2, host : "10.163.97.17:27002" }
...     ]
... }
{
        "_id" : "shard2",
        "members" : [
                {
                        "_id" : 0,
                        "host" : "10.163.97.15:27002",
                        "arbiterOnly" : true
                },
                {
                        "_id" : 1,
                        "host" : "10.163.97.16:27002"
                },
                {
                        "_id" : 2,
                        "host" : "10.163.97.17:27002"
                }
        ]
}
> rs.initiate(config);
{ "ok" : 1 }

设置第三个分片副本集
添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/shard3.conf
#配置文件内容
pidfilepath = /usr/local/mongodb/shard3/log/shard3.pid
dbpath = /usr/local/mongodb/shard3/data
logpath = /usr/local/mongodb/shard3/log/shard3.log
logappend = true

bind_ip = 0.0.0.0
port = 27003
fork = true

#打开web监控
httpinterface=true
rest=true

#副本集名称
replSet=shard3

#declare this is a shard db of a cluster;
shardsvr = true

#设置最大连接数
maxConns=20000

启动三台服务器的shard3 server
[root@D2-POMS15 ~]# mongod -f /usr/local/mongodb/conf/shard3.conf
about to fork child process, waiting until server is ready for connections.
forked process: 15742
child process started successfully, parent exiting

登陆一台服务器（不要在仲裁节点），初始化副本集
> use admin
switched to db admin
> config = {
...    _id : "shard3",
...     members : [
...         {_id : 0, host : "10.163.97.15:27003" },
...         {_id : 1, host : "10.163.97.16:27003" , arbiterOnly: true},
...         {_id : 2, host : "10.163.97.17:27003" }
...     ]
... }
{
        "_id" : "shard3",
        "members" : [
                {
                        "_id" : 0,
                        "host" : "10.163.97.15:27003"
                },
                {
                        "_id" : 1,
                        "host" : "10.163.97.16:27003",
                        "arbiterOnly" : true
                },
                {
                        "_id" : 2,
                        "host" : "10.163.97.17:27003"
                }
        ]
}
> rs.initiate(config);
{ "ok" : 1 }

可以看到目前已经启动了配置服务器和分片服务器。
[root@D2-POMS15 ~]# ps -ef | grep mongo | grep -v grep
root     15368     1  0 15:52 ?        00:00:07 mongod -f /usr/local/mongodb/conf/config.conf
root     15497     1  0 16:00 ?        00:00:04 mongod -f /usr/local/mongodb/conf/shard1.conf
root     15622     1  0 16:06 ?        00:00:02 mongod -f /usr/local/mongodb/conf/shard2.conf
root     15742     1  0 16:21 ?        00:00:00 mongod -f /usr/local/mongodb/conf/shard3.conf


5、配置路由服务器 mongos
在三台服务器上面添加配置文件：
[root@D2-POMS15 ~]# vi /usr/local/mongodb/conf/mongos.conf
#内容
pidfilepath = /usr/local/mongodb/mongos/log/mongos.pid
logpath = /usr/local/mongodb/mongos/log/mongos.log
logappend = true

bind_ip = 0.0.0.0
port = 20000
fork = true

#监听的配置服务器,只能有1个或者3个 configs为配置服务器的副本集名字
configdb = configs/10.163.97.15:21000,10.163.97.16:21000,10.163.97.17:21000

#设置最大连接数
maxConns=20000

启动三台服务器的mongos server
[root@D2-POMS15 ~]# mongos -f /usr/local/mongodb/conf/mongos.conf
about to fork child process, waiting until server is ready for connections.
forked process: 20563
child process started successfully, parent exiting

[root@D2-POMS15 ~]# mongo --port 20000
mongos> db.stats()
{
        "raw" : {
                "shard1/10.163.97.15:27001,10.163.97.16:27001" : {
                        "db" : "admin",
                        "collections" : 1,
                        "views" : 0,
                        "objects" : 3,
                        "avgObjSize" : 146.66666666666666,
                        "dataSize" : 440,
                        "storageSize" : 36864,
                        "numExtents" : 0,
                        "indexes" : 2,
                        "indexSize" : 65536,
                        "ok" : 1,
                        "$gleStats" : {
                                "lastOpTime" : Timestamp(0, 0),
                                "electionId" : ObjectId("7fffffff0000000000000001")
                        }
                },
                "shard2/10.163.97.16:27002,10.163.97.17:27002" : {
                        "db" : "admin",
                        "collections" : 1,
                        "views" : 0,
                        "objects" : 2,
                        "avgObjSize" : 114,
                        "dataSize" : 228,
                        "storageSize" : 16384,
                        "numExtents" : 0,
                        "indexes" : 2,
                        "indexSize" : 32768,
                        "ok" : 1,
                        "$gleStats" : {
                                "lastOpTime" : Timestamp(0, 0),
                                "electionId" : ObjectId("7fffffff0000000000000001")
                        }
                },
                "shard3/10.163.97.15:27003,10.163.97.17:27003" : {
                        "db" : "admin",
                        "collections" : 1,
                        "views" : 0,
                        "objects" : 2,
                        "avgObjSize" : 114,
                        "dataSize" : 228,
                        "storageSize" : 16384,
                        "numExtents" : 0,
                        "indexes" : 2,
                        "indexSize" : 32768,
                        "ok" : 1,
                        "$gleStats" : {
                                "lastOpTime" : Timestamp(0, 0),
                                "electionId" : ObjectId("7fffffff0000000000000002")
                        }
                }
        },
        "objects" : 7,
        "avgObjSize" : 127.71428571428571,
        "dataSize" : 896,
        "storageSize" : 69632,
        "numExtents" : 0,
        "indexes" : 6,
        "indexSize" : 131072,
        "fileSize" : 0,
        "extentFreeList" : {
                "num" : 0,
                "totalSize" : 0
        },
        "ok" : 1
}


6、启用分片
目前搭建了mongodb配置服务器、路由服务器，各个分片服务器，不过应用程序连接到mongos路由服务器并不能使用分片机制，还需要在路由服务器里设置分片配置，让分片生效。
登陆任意一台mongos
[root@D2-POMS15 ~]# mongo --port 20000
#使用admin数据库
mongos> use admin
switched to db admin
#串联路由服务器与分配副本集
mongos> sh.addShard("shard1/10.163.97.15:27001,10.163.97.16:27001,10.163.97.17:27001")
{ "shardAdded" : "shard1", "ok" : 1 }
mongos> sh.addShard("shard2/10.163.97.15:27002,10.163.97.16:27002,10.163.97.17:27002")
{ "shardAdded" : "shard2", "ok" : 1 }
mongos> sh.addShard("shard3/10.163.97.15:27003,10.163.97.16:27003,10.163.97.17:27003")
{ "shardAdded" : "shard3", "ok" : 1 }
#查看集群状态
mongos> sh.status()
--- Sharding Status ---
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
  shards:
        {  "_id" : "shard1",  "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002",  "state" : 1 }
        {  "_id" : "shard3",  "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003",  "state" : 1 }
  active mongoses:
        "3.4.7" : 1
 autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
                Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours:
                No recent migrations
  databases:


7、测试
目前配置服务、路由服务、分片服务、副本集服务都已经串联起来了，但我们的目的是希望插入数据，数据能够自动分片。连接在mongos上，准备让指定的数据库、指定的集合分片生效。
[root@D2-POMS15 ~]# mongo --port 20000
mongos> use admin
switched to db admin
#指定testdb分片生效
mongos> db.runCommand({enablesharding :"testdb"});
{ "ok" : 1 }
#指定数据库里需要分片的集合和片键
mongos> db.runCommand( { shardcollection : "testdb.table1",key : {id: 1} } )
{ "collectionsharded" : "testdb.table1", "ok" : 1 }
mongos> sh.status()
--- Sharding Status ---
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
  shards:
        {  "_id" : "shard1",  "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002",  "state" : 1 }
        {  "_id" : "shard3",  "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003",  "state" : 1 }
  active mongoses:
        "3.4.7" : 1
 autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
                Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours:
                4 : Success
  databases:
        {  "_id" : "testdb",  "primary" : "shard1",  "partitioned" : true }
                testdb.table1
                        shard key: { "id" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard1  1
                        { "id" : { "$minKey" : 1 } } -->> { "id" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)

以上就是设置testdb的 table1 表需要分片，根据 id 自动分片到 shard1 ，shard2，shard3 上面去。要这样设置是因为不是所有mongodb 的数据库和表 都需要分片！

测试分片：
#连接mongos服务器
[root@D2-POMS15 ~]# mongo --port 20000
#使用testdb
mongos> use testdb
switched to db testdb
#插入测试数据
mongos> for(var i=1;i<=100000;i++){db.table1.insert({id:i,"test1":"testval1"})}
WriteResult({ "nInserted" : 1 })
#查看分片情况
mongos> sh.status()
--- Sharding Status ---
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
  shards:
        {  "_id" : "shard1",  "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002",  "state" : 1 }
        {  "_id" : "shard3",  "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003",  "state" : 1 }
  active mongoses:
        "3.4.7" : 1
 autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
                Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours:
                6 : Success
  databases:
        {  "_id" : "testdb",  "primary" : "shard1",  "partitioned" : true }
                testdb.table1
                        shard key: { "id" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard1  1
                                shard2  1
                                shard3  1
                        { "id" : { "$minKey" : 1 } } -->> { "id" : 2 } on : shard2 Timestamp(2, 0)
                        { "id" : 2 } -->> { "id" : 20 } on : shard3 Timestamp(3, 0)
                        { "id" : 20 } -->> { "id" : { "$maxKey" : 1 } } on : shard1 Timestamp(3, 1)

可以看到这里分片很不均衡，原因是默认的chunkSize为64M，这里的数据量没有达到64M，可以修改一下chunkSize的大小，方便测试：
[root@D2-POMS15 ~]# mongo --port 20000
mongos> use config
switched to db config
mongos> db.settings.save( { _id:"chunksize", value: 1 } )
WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : "chunksize" })
mongos> db.settings.find();
{ "_id" : "balancer", "stopped" : false, "mode" : "full" }
{ "_id" : "chunksize", "value" : 1 }

修改后重新来测试：
mongos> use testdb
switched to db testdb
mongos> db.table1.drop();
true
mongos> use admin
switched to db admin
mongos> db.runCommand( { shardcollection : "testdb.table1",key : {id: 1} } )
{ "collectionsharded" : "testdb.table1", "ok" : 1 }
mongos> use testdb
switched to db testdb
mongos> for(var i=1;i<=100000;i++){db.table1.insert({id:i,"test1":"testval1"})}
WriteResult({ "nInserted" : 1 })
mongos> sh.status()
--- Sharding Status ---
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("599d34bf612249caec3fc9fe")
}
  shards:
        {  "_id" : "shard1",  "host" : "shard1/10.163.97.15:27001,10.163.97.16:27001",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/10.163.97.16:27002,10.163.97.17:27002",  "state" : 1 }
        {  "_id" : "shard3",  "host" : "shard3/10.163.97.15:27003,10.163.97.17:27003",  "state" : 1 }
  active mongoses:
        "3.4.7" : 1
 autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
                Balancer lock taken at Wed Aug 23 2017 15:54:40 GMT+0800 (CST) by ConfigServer:Balancer
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours:
                14 : Success
  databases:
        {  "_id" : "testdb",  "primary" : "shard1",  "partitioned" : true }
                testdb.table1
                        shard key: { "id" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard1  4
                                shard2  4
                                shard3  3
                        { "id" : { "$minKey" : 1 } } -->> { "id" : 2 } on : shard2 Timestamp(5, 1)
                        { "id" : 2 } -->> { "id" : 20 } on : shard3 Timestamp(6, 1)
                        { "id" : 20 } -->> { "id" : 9729 } on : shard1 Timestamp(7, 1)
                        { "id" : 9729 } -->> { "id" : 21643 } on : shard1 Timestamp(3, 3)
                        { "id" : 21643 } -->> { "id" : 31352 } on : shard2 Timestamp(4, 2)
                        { "id" : 31352 } -->> { "id" : 43021 } on : shard2 Timestamp(4, 3)
                        { "id" : 43021 } -->> { "id" : 52730 } on : shard3 Timestamp(5, 2)
                        { "id" : 52730 } -->> { "id" : 64695 } on : shard3 Timestamp(5, 3)
                        { "id" : 64695 } -->> { "id" : 74404 } on : shard1 Timestamp(6, 2)
                        { "id" : 74404 } -->> { "id" : 87088 } on : shard1 Timestamp(6, 3)
                        { "id" : 87088 } -->> { "id" : { "$maxKey" : 1 } } on : shard2 Timestamp(7, 0)

mongos> db.table1.stats()
{
        "sharded" : true,
        "capped" : false,
        "ns" : "testdb.table1",
        "count" : 100000,
        "size" : 5400000,
        "storageSize" : 1736704,
        "totalIndexSize" : 2191360,
        "indexSizes" : {
                "_id_" : 946176,
                "id_1" : 1245184
        },
        "avgObjSize" : 54,
        "nindexes" : 2,
        "nchunks" : 11,
        "shards" : {
                "shard1" : {
                        "ns" : "testdb.table1",
                        "size" : 2376864,
                        "count" : 44016,
                        "avgObjSize" : 54,
                        "storageSize" : 753664,
                        "capped" : false,
                        "nindexes" : 2,
                        "totalIndexSize" : 933888,
                        "indexSizes" : {
                                "_id_" : 405504,
                                "id_1" : 528384
                        },
                        "ok" : 1
                },
                "shard2" : {
                        "ns" : "testdb.table1",
                        "size" : 1851768,
                        "count" : 34292,
                        "avgObjSize" : 54,
                        "storageSize" : 606208,
                        "capped" : false,
                        "nindexes" : 2,
                        "totalIndexSize" : 774144,
                        "indexSizes" : {
                                "_id_" : 335872,
                                "id_1" : 438272
                        },
                        "ok" : 1
                },
                "shard3" : {
                        "ns" : "testdb.table1",
                        "size" : 1171368,
                        "count" : 21692,
                        "avgObjSize" : 54,
                        "storageSize" : 376832,
                        "capped" : false,
                        "nindexes" : 2,
                        "totalIndexSize" : 483328,
                        "indexSizes" : {
                                "_id_" : 204800,
                                "id_1" : 278528
                        },
                        "ok" : 1
                }
        },
        "ok" : 1
}

可以看到现在的数据分布就均匀多了。


８、后期运维
启动关闭
mongodb的启动顺序是，先启动配置服务器，在启动分片，最后启动mongos.
mongod -f /usr/local/mongodb/conf/config.conf
mongod -f /usr/local/mongodb/conf/shard1.conf
mongod -f /usr/local/mongodb/conf/shard2.conf
mongod -f /usr/local/mongodb/conf/shard3.conf
mongod -f /usr/local/mongodb/conf/mongos.conf
关闭时，直接killall杀掉所有进程
killall mongod
killall mongos

参考：
https://docs.mongodb.com/manual/sharding/
http://www.lanceyan.com/tech/arch/mongodb_shard1.html
http://www.cnblogs.com/ityouknow/p/7344005.html