详解MongoDB4.0构建分布式分片群集

wget https://fastdl.mongodb.org/linux/mongodb-linux-x86_64-4.0.0.tgz
tar zxvf mongodb-linux-x86_64-4.0.0.tgz -C /opt
mv /opt/mongodb-linux-x86_64-4.0.0/ /usr/local/mongodb

mkdir -p /data/mongodb/config
mkdir -p /data/mongodb/shard{1,2,3}
mkdir -p /data/mongodb/logs
touch /data/mongodb/logs/shard{1,2,3}.log
touch /data/mongodb/logs/mongos.log
touch /data/mongodb/logs/config.log
chmod 777 /data/mongodb/logs/*.log

useradd -M -s /sbin/nologin mongo
chown -R mongo:mongo /usr/local/mongodb
chown -R mongo:mongo /data/mongodb

echo 'export MONGODB_HOME=/usr/local/mongodb'  /etc/profile
echo 'export PATH=$PATH:$MONGODB_HOME/bin'  /etc/profile
source /etc/profile

ulimit -n 25000  //可以打开的最大文件数量
ulimit -u 25000  //用户最大可用的进程数
sysctl -w vm.zone_reclaim_mode=0 //内存不足时，从其他节点分配内存
# 从CentOS7开始，MongoDB会建议关闭系统的THP特性，否则可能会导致性能下降
echo never > /sys/kernel/mm/transparent_hugepage/enabled
echo never > /sys/kernel/mm/transparent_hugepage/defrag //*注意*这些优化都是临时的，重启失效

# vim config.conf
dbpath=/data/mongodb/config //数据文件存放位置
logpath=/data/logs/config.log  //日志文件
port=27018  //端口号
logappend=true
fork=true
maxConns=5000 
storageEngine=mmapv1
replSet=configs //复制集名称
configsvr=true  //设置参数为true
# mongod -f config.conf //启动config实例
scp /usr/local/mongodb/bin/config.conf root@192.168.125.120:/usr/local/mongodb/bin
scp /usr/local/mongodb/bin/config.conf root@192.168.125.121:/usr/local/mongodb/bin

mongo --port 27018
config={_id:"configs",members:[{_id:0,host:"192.168.125.119:27018"},{_id:1,host:"192.168.125.120:27018"},{_id:2,host:"192.168.125.121:27018"}]}  //创建复制集
rs.initiate(config)        //初始化复制集

# vim shard1.conf
dbpath=/data/mongodb/shard1
logpath=/data/logs/shard1.log
port=27001
logappend=true
fork=true
maxConns=5000 
storageEngine=mmapv1
shardsvr=true
# mongod -f shard1.conf
# 与另外两台配置实例配置文件相同，仅端口、数据文件存放及日志文件要改，只需配置完成后启动即可

mongo --port 27001
use admin
config={_id:"shard1",members:[{_id:0,host:"192.168.125.119:27001"},{_id:1,host:"192.168.125.120:27001"},{_id:2,host:"192.168.125.121:27001"}]}  //创建复制集
rs.initiate(config)        //初始化复制集

# vim mongos.conf
logpath=/data/mongodb/logs/mongos.log
logappend = true
port = 27017
fork = true
configdb = configs/192.168.125.119:27018,192.168.125.120:27018,192.168.125.121:27018
maxConns=20000

mongs -f /usr/local/mongodb/bin/mongos.conf
# 注意，这边启动mongos实例用的是mongos命令

mongo //默认进入27017端口
mongos> use admin
mongos> sh.addShard("shard1/192.168.125.119:27001,192.168.125.120:27001,172.16.10.29:27001")
mongos> sh.addShard("shard2/192.168.125.119:27002,192.168.125.120:27002,172.16.10.29:27002")
mongos> sh.status()      //查看群集状态
# 此处为添加两台分片服务器，后续添加的也会均匀分配分片数据

mongos> use config
mongos> db.settings.save({"_id":"chunksize","value":1})
# 设置块大小为1M是方便实验，不然需要插入海量数据

mongos> use school
mongos> show collections
mongos> for(i=1;i<=50000;i++){db.user.insert({"id":i,"name":"jack"+i})}
# 在school库的user表中循环写入五万条数据

mongos>sh.enableSharding("school")
# 我们可以自定义需要分片的库或表

mongos> db.user.createIndex({"id":1})
# 以"id"作为索引
mongos> sh.shardCollection("school.user",{"id":1})
# 根据"id"对user表进行分片
mongos> sh.status()
# 查看分片情况
mongos> sh.help()
# 查看分片相关的命令